WO1994023752A1 - Drug delivery system - Google Patents

Drug delivery system Download PDF

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Publication number
WO1994023752A1
WO1994023752A1 PCT/GB1994/000806 GB9400806W WO9423752A1 WO 1994023752 A1 WO1994023752 A1 WO 1994023752A1 GB 9400806 W GB9400806 W GB 9400806W WO 9423752 A1 WO9423752 A1 WO 9423752A1
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WO
WIPO (PCT)
Prior art keywords
lectin
active agent
pharmacologically active
drug delivery
drug
Prior art date
Application number
PCT/GB1994/000806
Other languages
French (fr)
Inventor
John David Smart
David John Rogers
Original Assignee
University Of Portsmouth Enterprise Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB939307904A external-priority patent/GB9307904D0/en
Priority claimed from GB939324682A external-priority patent/GB9324682D0/en
Application filed by University Of Portsmouth Enterprise Limited filed Critical University Of Portsmouth Enterprise Limited
Priority to AU65100/94A priority Critical patent/AU6510094A/en
Priority to GB9523475A priority patent/GB2292887B/en
Publication of WO1994023752A1 publication Critical patent/WO1994023752A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
    • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
    • A61K9/167—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction with an outer layer or coating comprising drug; with chemically bound drugs or non-active substances on their surface
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/62—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being a protein, peptide or polyamino acid
    • A61K47/64—Drug-peptide, drug-protein or drug-polyamino acid conjugates, i.e. the modifying agent being a peptide, protein or polyamino acid which is covalently bonded or complexed to a therapeutically active agent
    • A61K47/6415—Toxins or lectins, e.g. clostridial toxins or Pseudomonas exotoxins
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/69—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the conjugate being characterised by physical or galenical forms, e.g. emulsion, particle, inclusion complex, stent or kit
    • A61K47/6921—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the conjugate being characterised by physical or galenical forms, e.g. emulsion, particle, inclusion complex, stent or kit the form being a particulate, a powder, an adsorbate, a bead or a sphere
    • A61K47/6927—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the conjugate being characterised by physical or galenical forms, e.g. emulsion, particle, inclusion complex, stent or kit the form being a particulate, a powder, an adsorbate, a bead or a sphere the form being a solid microparticle having no hollow or gas-filled cores
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/10—Dispersions; Emulsions
    • A61K9/127—Liposomes
    • A61K9/1271—Non-conventional liposomes, e.g. PEGylated liposomes, liposomes coated with polymers

Definitions

  • the present invention relates to a sustained release drug delivery system.
  • the present invention relates to a sustained release drug delivery system comprising a pharmacologically active agent and a lectin.
  • the invention specifically relates to the sustained delivery of ophthalmic drugs.
  • aqueous drug dosage forms such as eye drops suffer from the disadvantage that the applied drug is rapidly removed by drug dilution and drug elimination caused by the continuous turnover of the tear fluid.
  • the present invention overcomes the above discussed disadvantage, in that the system of the present invention is capable of binding to specific tissue sites. The binding of the drug delivery system, ensures that the drug to be delivered is releasably bound at the site of action. Thus it does not suffer from the disadvantage of aqueous drug dosage forms of being susceptible to being rapidly removed.
  • the present invention provides a drug delivery system comprising a lectin and a pharmacologically active agent wherein the active agent is reversibly bound to the lectin.
  • the pharmacologically active agent is a drug or pharmacologically active material.
  • the pharmacologically active agent is a microparticle or a nanoparticle comprising a pharmaceutical.
  • the size of the microparticle or nanoparticle should be such that it does not cause irritation to the eye.
  • the lectin is reversibly bound on an outer surface of the microparticle or nanoparticle.
  • the pharmacologically active agent is a liposome containing a pharmaceutical.
  • the lectin may be reversibly bound to an outer surface of the liposome.
  • the pharmacologically active agent is a gel having a pharmaceutical dispersed therein.
  • the pharmacologically active agent is bound to an ion- exchange resin or a macromolecular carrier such as albumin, polyacrylic acid or hyaluronic acid.
  • the pharmacologically active agent may comprise any system generally known to be suitable for sustained drug release and to which lectins may reversibly bind.
  • the drug delivery system of the present invention is to be brought into contact with, body surfaces including the eye and less aptly the mucous membranes of the mouth, the nose, the gastrointestinal tract, the anus and the vagina.
  • the pharmaceutically active agents which are particularly useful for contact with body surfaces including the eye include antibacterials as hereinafter described, antibiotics such as chloramphenicol, oxytetracycline, tetracycline, erythromycin; antifungal agents such as griseofulvin, amphotericin B, nystatin and the like and econazole and miconazole which are especially useful in the treatment of fungal infections of the mouth and vagina; antivirals such as idoxuridine, anaesthetics as hereafter described, anti-allergy compounds, and spermicides for vaginal use.
  • antibiotics such as chloramphenicol, oxytetracycline, tetracycline, erythromycin
  • antifungal agents such as griseofulvin, amphotericin B, nystatin and the like and econazole and miconazole which are especially useful in the treatment of fungal infections of the mouth and vagina
  • antivirals such as idoxuridine
  • the amount of pharmaceutical present in the pharmacologically active agent will depend on the type of body surface to be treated and the frequency of treatment. Generally the amount of pharmaceutical present will be between l ⁇ g and lOmg.
  • lectins There are numerous references in the literature to lectins . They may be classified as either glycoproteins or proteoglycans . It is well known that lectins are capable of binding to sugar residues. Lectins can be characterised according to the specific sugar residue to which they bind.
  • the pharmacologically active agent may be releasably bound to the lectin by covalent or non-covalent bonding.
  • the pharmacologically active agent is non-covalently bound to the lectin.
  • the non-covalent bonding may be by means of a non-labile bond such as by means of an ionic bond or by means of hydrogen bonding.
  • suitable forms of bonding will be known to those skilled in the art.
  • the lectins suitable for use in the present invention should have at least two binding sites ie. be bi-valent.
  • a first binding site is for binding to the specific sugar residue in the body tissue.
  • the sugar residue may be any residue normally found in animal or human tissue. Examples of such sugar residues include N- acetlyglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), -D mannose, ⁇ -D-glucose and -L-fucose.
  • the lectin releasably binds to the above sugar residues on coming into contact therewith.
  • the second binding site is for binding the pharmacologically active agent.
  • the pharmacologically active agent may be any agent capable of binding to the lectin.
  • the pharmacologically active agent comprises an ophthalmically active pharmaceutical.
  • the cornea is the outer facing surface of the eyeball and is a transparent avascular structure composed of five layers (Fig 1), it is the main functional barrier to the ocular penetration of drugs and has an extremely regular anatomical structure (Haskjold, E, Refsum, S B, Bjerknes, R (1980) APMIS 98,959-976.
  • the conjunctiva is attached to the sclera at the corneal margin and is reflected back to form the inner lining of the eyelid.
  • the surface of the cornea and conjunctiva are both mainly squamous stratified epithelia which are covered by a filamentous material called the glycocalyx that contains highly acidic glycoproteins. Overlying the glycocalyx is a mucin layer. (Wolff E (1961) In: “Anatomy of the Eye and Orbit” (Rev. by Last, R J London) 6th Ed.) which forms the inner part of the tear film. It is believed to be weakly bonded to the glycocalyx and there are chemical similarities in the glycoprotein constituents of the two.
  • Ocular tissues from rats have served as important animal models in experimental eye research.
  • lectin binding sites have been identified in the precorneal region using fixed tissues, however we have now demonstrated lectin binding of unfixed corneal and conjunctival tissues.
  • the drug delivery system of the present invention is suitable for the delivery of drugs to the precorneal region of the eye, thus allowing prolonged delivery of drugs to treat a range of conditions.
  • Suitable ophthalmic agents include anti-infective agents including antibacterials such a silver sulphadiazine, chloramphenicol, antibiotics such as econazole and miconazole, aminoglycosides including salts of neomycin or gentamicin, sodium sulphacetamide, and silver nitrate, mydriatics and cycloplegics such as atropine sulphate, cyclopentolatehydrochloride, phenylephrinehydrochloride and tropicamide; agents useful in the treatment of glaucoma and ocular hypertension, anti glaucoma agents, which include cholinergic agonists such as physostigmine salicylate, pilocarpine and salts thereof for example pilocarpine nitrate, sympathomimetics such as adrenaline and its salts, for example adrenaline tartrate, adrenaline with guanethidine, 6-blockers such as timolol and its salts, for
  • a method of treatment of a bacterial, fungal viral or allergic disorder which comprises the administration of a pharmacologically active agent to a patient suffering from such a disorder by the use of a drug delivery system as hereinbefore described.
  • a method of treatment of an ophthalmic disorder which comprises administration of a pharmacologically active agent to a patient suffering from such a disorder by the use of a drug delivery system as hereinbefore described.
  • the system may be prepared by allowing the lectin and a specific pharmacologically active agent to react together so as to form a bond therebetween.
  • the method of carrying out such a reaction may be according to any of the methods known to those skilled in the art.
  • the lectin is chosen from the group Con-A (Jack bean), Pisurn sativum (garden pea), Arachie hypogea (peanut), Helix pomatia (Roman edible snail), lycopersicon esculentum (tomato) and Ulex europaeus 1 (gorse).
  • Con-A Jack bean
  • Pisurn sativum garden pea
  • Arachie hypogea peanut
  • Helix pomatia Roman edible snail
  • lycopersicon esculentum tomato
  • Ulex europaeus 1 Ulex europaeus 1
  • Other suitable lectins include those isolated from potatoes, algae, and the horse-shoe carb as well as from Solanum tuberosum and Pisum sativum.
  • the lectin is either Helix pomatia (HPA) or Lycopersicon esculentum (LEA).
  • the drug delivery system of the present invention may comprise further pharmaceutically acceptable components in addition to the lectin and pharmacologically active agent.
  • an additional component may be a buffer, eg. TBS.
  • Such additional components may serve for example as a stabiliser or as a liquid vehicle, ie. a liquid phase for carrying the drug delivery system of the present invention.
  • the additional component should be storage stable and should not interact with either the lectin or the pharmacologically active agent.
  • the present invention further provides a pharmaceutical formulation comprising the drug delivery system of the present invention and a liquid vehicle.
  • the drug delivery system of the present invention may be stored and delivered in a pure undiluted state.
  • the tissues were blotted dry and placed in 2.5 - 3.0ml of 5mg L "1 streptavidin peroxidase in 0.125M TBS (made isotonic with NaCl) for 1 hr.
  • Tissues were then washed in 0.05M TBS blotted dry and incubated in a solution containing 0.05% w/v 3,3'-diaminobenzidine tetrahydrochloride (DAB) , 0.05M TBS and 0.015% v/v hydrogen peroxide for 10 min at room temperature.
  • DAB 3,3'-diaminobenzidine tetrahydrochloride
  • 0.05M TBS 0.015% v/v hydrogen peroxide for 10 min at room temperature.
  • fixation the tissues were place in 4% phosphate buffered formaldehyde for 24 hrs.
  • the procedure was completed 3 times for each lectin, and the binding was evaluated subjectively using the following scoring system: intensity of staining, absent to heavy (0/++++); no coverage to complete coverage (0- 5).
  • Example 1 Corneal and conjunctival epithelia from recently killed male Wistar rats were incubated with lO ⁇ g/ml of the appropriate biotinylated lectin in 0.05M tris buffered saline (TBS) pH 7.6, containing lmMCaCl 2 for 10s and 30s. Tissues were washed with TBS and placed in 5 ⁇ g/ml streptavidin peroxidase in isotonic 0.125M TBS for lh.
  • TBS tris buffered saline
  • the tissues were incubated in a solution containing 0.05% w/v 3,3'- diaminobenzidine tetrahydrochloride (DAB), 0.05M TBS and 0.15% v.v hydrogen peroxide for 10 min at room temperature.
  • DAB 3,3'- diaminobenzidine tetrahydrochloride
  • the tissues were incubated in the lectin solution for 10s then washed by aggitating in TBS and lmMCaCl 2f pH7.6 for 30min before proceeding. 5 ⁇ m sections were then cut and counterstained with 2% methylgreen. Each section was initially examined using light microscopy at x400 magnification. The presence of lectin on the surface epithelia was indicated by the brown precipitate of DAB.
  • the binding was evaluated subjectively using stain intensity (absent to heavy) and surface cover (no to complete coverage), as described by Nicholls et al (1993) J. Pharm, Pharmacol, 45:1122.
  • the stain width on the surface epithelia was measured at 100 representative positions on each section using video microscopy at x3432 magnification, as a measure of the extent of lectin binding. Staining was evident on both the corneal and conjunctival surfaces after 10 and 30s with both HPA and STA. These exposure times are more representative of the residence time of eye drops in the precorneal region than the 15 min used in previous work. Washing for 30 min had minimial effects on the staining observed with STA and HPA.
  • the lectin from C. fragile was isolated by affinity chromatography from aqueous extract of the plant using methods described in Rogers, D.J., Loveless, R.W. and Balding, P. (1986) Isolation and characterisation of the lectins from sub-species of Codium fragile. In: Lectins, Biology, Biochemistry, Clinical Biochemistry, Vol 5. Eds T.C. Bog-Hansen and E. Van Driessche. Walter de Gruyter, Berlin, pp 155-160. Approximately half of the purified lectin was labelled with biotin using the technique described in R.F. Masseyeff, W.H. Albert and N.A. Staines Eds. Methods of Immunological Analysis, Vol 2.
  • Unlabelled C. fragile lectin was applied to unfixed rat eye. Following washing, biotinylated Dolicho ⁇ biflorus lectin (GalNAc-specific) was applied to the eye. The presence of biotinylated D. biflorus lectin was then assessed using streptavidin-peroxidase and 3',3- diaminobenzidine tetrahydrochloride (DAB).
  • DAB 3',3- diaminobenzidine tetrahydrochloride
  • Biotinylated C. fragile lectin was applied to rat eyes. Binding was assessed with streptavidin-peroxidase DAB as above. Microscopical examination revealed the presence of a dense brown precipitate of DAB on the corneal and conjunctival surfaces. This investigation was repeated using various dilutions of the biotinylated C. fragile lectin. The intensity of the DAB brown precipitate on corneal and conjunctival surfaces was proportional to the concentration of the biotinylated C. fragile lectin used.
  • the GAlNAc-binding lectin from the green marine alga binds to the surfaces of rat cornea and conjunctiva and therefore has potential value in topical drug location in the eye. It is therefore believed that lectins derived from certain marine algae may be suitable agents for incorporation in topical drug delivery systems for the eye and mouth.
  • the aim of this study was to identify lectins that could be used to retain a dosage from within the oral cavity in order to prolong localised drug delivery or to enhance systemic drug absorption.
  • This initial study investigated the binding to viable human buccal epithelial cells of a variety of different lectins. The method used was adapted from that described by Nicholls T.J. et al (1993) J. Phar . Pharmac. 45 1122. Human buccal cells were gently scrapped from the buccal surface with a wooden spatula which was then immersed in 10 ml of 0.05M tris buffered saline (TBS) pH 7.6. The cell suspension was filtered through a Nucleopore membrane filter, pore size 3 ⁇ m.
  • the filter and retained cells was immersed in 5 ml of lOmgL "1 biotinylated lectin (BL) in TBS, containing lmMCaCl 2 , for 30 min and washed twice at 5 min intervals in 0.05M TBS, before treating with 5mgL _1 streptavidin peroxidase (SP) in 0.125M TBS for 1 h.
  • the filter was re-washed twice in 0.05M TBS and 0.015% (v/v) H z 0 2 for 7 min.
  • the filter was counterstained with methyl green after soaking in 95% ethanol. Appropriate controls were completed omitting the SP, DAB or the lectin.
  • the surface of the filter was examined using light microscopy at x400 magnification.
  • the intensity of the DAB staining, indicating bound lectin, was evaluated subjectively using the following scoring: Strong staining (+++) intermediate staining (++), weak staining (+) and no staining (0).
  • the lectins tested bind to unfixed buccal mucosal cells, and so may be used as a means of enhancing drug delivery to the oral cavity.
  • lectins identified in the preceding studies as ' ligands' to anchor an appropriate drug for delivery to the mucosal surfaces of the eye, mouth, vagina or the respiratory tract.
  • the delivery systems envisaged will be of the following types:
  • Lectin/ macromolecule/ drug complexes In this system an intervening polymer or macromolecule is included in the formulation as a spacer/carrier device. Any non-toxic water soluble polymer of a water soluble grade would be appropriate. Some possible formulations are described below.
  • the drug e.g. pilocarpine nitrate, chlorhexidine acetate.
  • Formulations should be made isotonic using sodium chloride, sterilised by autoclaving or filtration and a preservative (chlorocresol 0.05%, phenylmercuric nitrate 0.002%, benzalkonium chloride 0.01% or chlorhexidine acetate 0.01%) added.
  • microparticles on Concanavalin A can be produced using a standard procedure (e.g. water in oil emulsification followed by cross- linking, drying and filtering) by first blocking the sugar binding sites with methyl mannopyranoside, then cross-linking with glutaraldehyde (Pai, C. et al. J. Pharm. Sci. 81, 532-536, 1992). Continuous washing with cold acetate buffer will remove the bound sugar and Schiff base-linkages reduced with sodium cyanoborohydride. It may therefore be possible to introduce the drug directly into a lectin microparticle during the cross-linking process or afterwards by allowing the microparticles to swell in the presence of a concentrated solution of the drug. This system may be made isotonic with sodium chloride and an appropriate preservative added for ocular drug delivery. Similar formulations would be appropriate for the mouth and vagina.
  • liposomes The ophthalmic use of liposomes has been well reported in the literature e.g. to deliver triamcinolone acetonide (Singh K., Mezei, M. Int. J. Pharm. 16, 1993, 339-344) and pilocarpine HC1 (Benita S. et al., J. Microencapsulation 1, 1984, 203-216).
  • the formulation and therapeutic effects of liposomes for local and systemic delivery of drugs has been well documented.
  • proteoliposomes containing a derivative of Concanavalin A has been reported (Francis S.E. et al. Biochimica et Biophyscia Act, 1062, 1991, 117-122). It would therefore seem reasonable to combine the two technologies to produce liposomes that will bind to ocular, oral and vaginal surfaces, using the lectins identified in our studies.

Abstract

A drug delivery system is provided which comprises a lectin and a pharmacologically active agent in which the active agent is releasably bound to the lectin. The lectin has been found to selectively attach to glycoproteins e.g. within the cornea of the eye, thereby enabling a drug to be selectively delivered thereto.

Description

DRUG DELIVERY SYSTEM
The present invention relates to a sustained release drug delivery system. In particular the present invention relates to a sustained release drug delivery system comprising a pharmacologically active agent and a lectin. The invention specifically relates to the sustained delivery of ophthalmic drugs.
Thus it is an established fact that simple aqueous drug dosage forms such as eye drops suffer from the disadvantage that the applied drug is rapidly removed by drug dilution and drug elimination caused by the continuous turnover of the tear fluid. There is thus a need for a drug delivery system which does not suffer from the above disadvantages. The present invention overcomes the above discussed disadvantage, in that the system of the present invention is capable of binding to specific tissue sites. The binding of the drug delivery system, ensures that the drug to be delivered is releasably bound at the site of action. Thus it does not suffer from the disadvantage of aqueous drug dosage forms of being susceptible to being rapidly removed.
The present invention provides a drug delivery system comprising a lectin and a pharmacologically active agent wherein the active agent is reversibly bound to the lectin. In one embodiment of the present invention the pharmacologically active agent is a drug or pharmacologically active material.
In a further embodiment of the present invention the pharmacologically active agent is a microparticle or a nanoparticle comprising a pharmaceutical. The size of the microparticle or nanoparticle should be such that it does not cause irritation to the eye. According to this embodiment the lectin is reversibly bound on an outer surface of the microparticle or nanoparticle.
In a still further embodiment of the present invention the pharmacologically active agent is a liposome containing a pharmaceutical. The lectin may be reversibly bound to an outer surface of the liposome.
In a further embodiment of the present invention the pharmacologically active agent is a gel having a pharmaceutical dispersed therein. Alternatively the pharmacologically active agent is bound to an ion- exchange resin or a macromolecular carrier such as albumin, polyacrylic acid or hyaluronic acid..
It will be appreciated by those skilled in the art that the pharmacologically active agent may comprise any system generally known to be suitable for sustained drug release and to which lectins may reversibly bind.
It is envisaged that the drug delivery system of the present invention is to be brought into contact with, body surfaces including the eye and less aptly the mucous membranes of the mouth, the nose, the gastrointestinal tract, the anus and the vagina.
The pharmaceutically active agents which are particularly useful for contact with body surfaces including the eye include antibacterials as hereinafter described, antibiotics such as chloramphenicol, oxytetracycline, tetracycline, erythromycin; antifungal agents such as griseofulvin, amphotericin B, nystatin and the like and econazole and miconazole which are especially useful in the treatment of fungal infections of the mouth and vagina; antivirals such as idoxuridine, anaesthetics as hereafter described, anti-allergy compounds, and spermicides for vaginal use.
The amount of pharmaceutical present in the pharmacologically active agent will depend on the type of body surface to be treated and the frequency of treatment. Generally the amount of pharmaceutical present will be between lμg and lOmg.
There are numerous references in the literature to lectins . They may be classified as either glycoproteins or proteoglycans . It is well known that lectins are capable of binding to sugar residues. Lectins can be characterised according to the specific sugar residue to which they bind.
The pharmacologically active agent may be releasably bound to the lectin by covalent or non-covalent bonding. In a preferred embodiment the pharmacologically active agent is non-covalently bound to the lectin. Thus for example the non-covalent bonding may be by means of a non-labile bond such as by means of an ionic bond or by means of hydrogen bonding. Other examples of suitable forms of bonding will be known to those skilled in the art.
The lectins suitable for use in the present invention should have at least two binding sites ie. be bi-valent. A first binding site is for binding to the specific sugar residue in the body tissue. Thus the sugar residue may be any residue normally found in animal or human tissue. Examples of such sugar residues include N- acetlyglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), -D mannose, α-D-glucose and -L-fucose. The lectin releasably binds to the above sugar residues on coming into contact therewith. The second binding site is for binding the pharmacologically active agent. As explained above, the pharmacologically active agent may be any agent capable of binding to the lectin.
In a preferred embodiment of the present invention, the pharmacologically active agent comprises an ophthalmically active pharmaceutical.
On instillation of a liquid or semisolid dosage form into the precorneal region it will make initial contact with two membranes, namely the cornea and conjunctiva. The cornea is the outer facing surface of the eyeball and is a transparent avascular structure composed of five layers (Fig 1), it is the main functional barrier to the ocular penetration of drugs and has an extremely regular anatomical structure (Haskjold, E, Refsum, S B, Bjerknes, R (1980) APMIS 98,959-976. The conjunctiva is attached to the sclera at the corneal margin and is reflected back to form the inner lining of the eyelid. It is vascularised on the inner eyelid and has an outer mucous membrane layer containing regions of mucus secreting columnar cells. It assists in the spreading of the tear film to maintain a uniform thickness which is essential for normal vision Nicholas, B. Dawson, C.R., Togni, B (1985) Invest. Opthamol. Vis. Sci. 24,570567. The surface of the cornea and conjunctiva are both mainly squamous stratified epithelia which are covered by a filamentous material called the glycocalyx that contains highly acidic glycoproteins. Overlying the glycocalyx is a mucin layer. (Wolff E (1961) In: "Anatomy of the Eye and Orbit" (Rev. by Last, R J London) 6th Ed.) which forms the inner part of the tear film. It is believed to be weakly bonded to the glycocalyx and there are chemical similarities in the glycoprotein constituents of the two.
Ocular tissues from rats have served as important animal models in experimental eye research. In previous studies lectin binding sites have been identified in the precorneal region using fixed tissues, however we have now demonstrated lectin binding of unfixed corneal and conjunctival tissues.
In particular the drug delivery system of the present invention is suitable for the delivery of drugs to the precorneal region of the eye, thus allowing prolonged delivery of drugs to treat a range of conditions.
Suitable ophthalmic agents include anti-infective agents including antibacterials such a silver sulphadiazine, chloramphenicol, antibiotics such as econazole and miconazole, aminoglycosides including salts of neomycin or gentamicin, sodium sulphacetamide, and silver nitrate, mydriatics and cycloplegics such as atropine sulphate, cyclopentolatehydrochloride, phenylephrinehydrochloride and tropicamide; agents useful in the treatment of glaucoma and ocular hypertension, anti glaucoma agents, which include cholinergic agonists such as physostigmine salicylate, pilocarpine and salts thereof for example pilocarpine nitrate, sympathomimetics such as adrenaline and its salts, for example adrenaline tartrate, adrenaline with guanethidine, 6-blockers such as timolol and its salts, for example timolol maleate, other agents suitable for the treatment of glaucoma which include α methyl noradrenaline, α-methyl adrenaline, triamterene, clonidine, prazosin, the dipivoyl esters of adrenaline, noradrenaline, α-methyl adrenaline, α-methyl noradrenaline and their addition salts, anaesthetics such as amethocaine hydrochloride, benoxinate hydrochloride and lignocaine hydrochloride, anti-allergy compounds such as sodium cromoglycate, anti inflammatory agents including steroids such as betamethasone, cortisone, hydrocortisone, dexamethasone, fluocoriolone, prednisolone and triamcinolone and their pharmacologically acceptable salts such as acetate or sodium phosphate, and including non-steroidal anti- inflammatory agents such as indomethacin, tolmetin and their salts for example with alkali metals such as sodium, and stains such as fluorescein sodium and rose Bengal. The drug deliver system of the present invention, allows both water soluble and insoluble ophthalmic agents to be delivered to the eye.
According to the invention we provide a method of treatment of a bacterial, fungal viral or allergic disorder which comprises the administration of a pharmacologically active agent to a patient suffering from such a disorder by the use of a drug delivery system as hereinbefore described. In particular we provide a method of treatment of an ophthalmic disorder which comprises administration of a pharmacologically active agent to a patient suffering from such a disorder by the use of a drug delivery system as hereinbefore described.
In a yet further embodiment of the present invention, there is provided use of a lectin in the manufacture of a medicament.
In one embodiment of the drug delivery system of the present invention, the system may be prepared by allowing the lectin and a specific pharmacologically active agent to react together so as to form a bond therebetween. The method of carrying out such a reaction, may be according to any of the methods known to those skilled in the art.
In a further embodiment of the present invention, the lectin is chosen from the group Con-A (Jack bean), Pisurn sativum (garden pea), Arachie hypogea (peanut), Helix pomatia (Roman edible snail), lycopersicon esculentum (tomato) and Ulex europaeus 1 (gorse). Other suitable lectins include those isolated from potatoes, algae, and the horse-shoe carb as well as from Solanum tuberosum and Pisum sativum. Preferably the lectin is either Helix pomatia (HPA) or Lycopersicon esculentum (LEA).
The drug delivery system of the present invention may comprise further pharmaceutically acceptable components in addition to the lectin and pharmacologically active agent. Thus for example, an additional component may be a buffer, eg. TBS. Such additional components may serve for example as a stabiliser or as a liquid vehicle, ie. a liquid phase for carrying the drug delivery system of the present invention. The additional component should be storage stable and should not interact with either the lectin or the pharmacologically active agent. Thus the present invention further provides a pharmaceutical formulation comprising the drug delivery system of the present invention and a liquid vehicle.
In an alternative embodiment of the present invention, the drug delivery system of the present invention may be stored and delivered in a pure undiluted state.
The following examples illustrate the binding of the carrier protein to sugar residues.
Example 1
Screening of a range of lectins for their ability to bind to the rat corneal and coniunctival epithelia
An experimental procedure was followed based on that described by Bishop et al (1991) Br, J. Opthalmol, 75 : 22-27 but modified for use with fresh tissues. The upper eyelids and eyeballs were removed from recently sacrificed male Wistar rats (approximately 200g). It was established in preliminary work that endogenous enzyme blockage and trypsinisation were not necessary. The eyelids and eyeballs were incubated for 15 min at room temperature in 2.5-3.0ml of 0.05M isotonic tris buffered saline (TBG) containing ImM CaCl2 and 10 g L"1 biotinylated lectin. After rinsing with TBS the tissues were blotted dry and placed in 2.5 - 3.0ml of 5mg L"1 streptavidin peroxidase in 0.125M TBS (made isotonic with NaCl) for 1 hr. Tissues were then washed in 0.05M TBS blotted dry and incubated in a solution containing 0.05% w/v 3,3'-diaminobenzidine tetrahydrochloride (DAB) , 0.05M TBS and 0.015% v/v hydrogen peroxide for 10 min at room temperature. For fixation the tissues were place in 4% phosphate buffered formaldehyde for 24 hrs. Dehydration of the tissues was completed in a Histrokinette (Type B7326, British American Optical Company Ltd., Slough, UK) using graded alcohols followed by three changes of 1,1,1, trichloroethane and immersion into wax. Tissues were then vacuum embedded in paraffin wax using a Hearson Vacuum Embedder for 1 to 1.5 hr 5μm sections were cut from the centre of the wax block using a microtome (Glee Medical Equipment Ltd., London, UK) and dried onto microscope slides at 45°C for 12 hr. Paraffin sections were dewaxed in xylene and passed through graded alcohols to distilled water, then counterstained with 2% methylgreen for 30 min. The tissues were dehydrated through graded alcohols, placed into xylene and mounted in DPX. Results were evaluated qualitatively for surface cover and stain intensity at x400 magnification using a light microscope (model YS2-H, Nikon, Tokyo, Japan).
A series of controls were included in the initial investigations to eliminate the possibility of background staining and endogenous enzyme activity. These were the use of an endogenous enzyme block (0.5% (v/v) H202 in absolute alcohol containing 0.4% (v/v) IM HC1) both with and without the lectin; enzyme block with DAB and no lectin or streptavidin; and DAB with no streptavidin, lectin or enzyme block.
The procedure was completed 3 times for each lectin, and the binding was evaluated subjectively using the following scoring system: intensity of staining, absent to heavy (0/++++); no coverage to complete coverage (0- 5).
All of the lectins used bound to the surface epithelium of the cornea and conjunctiva and it can therefore be concluded that GlcNAc (N-acetlyglucosamine) , GalNAc (N- acetylgalactosamine) , α-D-glucose and α-L-fucose were all present.
The results of the examples carried out according to the above described procedures are indicated in Table 1. Thus it is clear that fresh corneal and conjunctival tissues bind all of the lectins tested. The above results also show (contrary to what was believed before (Bishop, P N et al 1991),), that fresh corneal and conjunctival tissues bind the following lectins: A hypogea, U curopaeus I and H pomatia.
It can be seen from the above results, that two of the preferred lectins are H pomatia and L esculentum.
It is thus clear that according to the present invention, depending on the sugars residues naturally present at the site to be targeted for drug delivery, a particular genus of lectin can be chosen which is known to bind to the sugar residue. The chosen lectin can be used to provide the drug delivery system of the present invention. It thus will be appreciated that the applicants do not wish the invention to be limited by the lectins specifically mentioned.
Table 1
Lectin binding to corneal and conjunctival tissues (α-p)
Figure imgf000015_0001
Stain intensity : absent to heavy (0/++++) Surface cover : no cover to complete coverage (0-5)
Example 2
Effect on binding of reducing the exposure time and subjecting the bound lectin to washing with buffer, using a semi-Quantitative video microscopy technigue. The methods used were based on the procedure of Example 1. Corneal and conjunctival epithelia from recently killed male Wistar rats were incubated with lOμg/ml of the appropriate biotinylated lectin in 0.05M tris buffered saline (TBS) pH 7.6, containing lmMCaCl2 for 10s and 30s. Tissues were washed with TBS and placed in 5μg/ml streptavidin peroxidase in isotonic 0.125M TBS for lh. After washing in 0.05M TBS the tissues were incubated in a solution containing 0.05% w/v 3,3'- diaminobenzidine tetrahydrochloride (DAB), 0.05M TBS and 0.15% v.v hydrogen peroxide for 10 min at room temperature. In the stability investigation the tissues were incubated in the lectin solution for 10s then washed by aggitating in TBS and lmMCaCl2fpH7.6 for 30min before proceeding. 5μm sections were then cut and counterstained with 2% methylgreen. Each section was initially examined using light microscopy at x400 magnification. The presence of lectin on the surface epithelia was indicated by the brown precipitate of DAB. The binding was evaluated subjectively using stain intensity (absent to heavy) and surface cover (no to complete coverage), as described by Nicholls et al (1993) J. Pharm, Pharmacol, 45:1122. The stain width on the surface epithelia was measured at 100 representative positions on each section using video microscopy at x3432 magnification, as a measure of the extent of lectin binding. Staining was evident on both the corneal and conjunctival surfaces after 10 and 30s with both HPA and STA. These exposure times are more representative of the residence time of eye drops in the precorneal region than the 15 min used in previous work. Washing for 30 min had minimial effects on the staining observed with STA and HPA. When examined by video microscopy, there was a significant difference (p<0.05, Student t-test) in stain width between 10s and 30s on the corneal epithelia with both lectins, however with the conjunctival epithelia a significant difference was only obtained with STA (Table 2). Surprisingly, washing with TBS seemed to increase the width of the staining band. HPA had a greater stain width on both tissues than STA, however, direct comparison between the two lectins is complicated by differing molecular weights and biotin : lectin ratios.
Table 2 Mean stain width (μm) of HPA and STA on rat ocular tissues, at x 3432 magnification (n = 100).
Figure imgf000017_0001
It can be concluded from these investigations that HPA and STA bind rapidly and demonstrate resistance to simple washing.
Example 3
Binding of the α-D-N-Acetylgalactosamine (GalNAc^ lectin from the green marine alga Codium fragile ssy tomentosoides to rat cornea and conjunctiva.
The lectin from C. fragile was isolated by affinity chromatography from aqueous extract of the plant using methods described in Rogers, D.J., Loveless, R.W. and Balding, P. (1986) Isolation and characterisation of the lectins from sub-species of Codium fragile. In: Lectins, Biology, Biochemistry, Clinical Biochemistry, Vol 5. Eds T.C. Bog-Hansen and E. Van Driessche. Walter de Gruyter, Berlin, pp 155-160. Approximately half of the purified lectin was labelled with biotin using the technique described in R.F. Masseyeff, W.H. Albert and N.A. Staines Eds. Methods of Immunological Analysis, Vol 2. VCH, Weinheim, 1993, p 466. Two methods were then used to establish binding of the labelled and unlabelled lectin to rat cornea and conjunctiva. Preparation and treatment of rat eyes with biotinylated lectins and streptavidin-peroxidase DAB were conducted according to the method described in Example 1. 1) Indirect method
Unlabelled C. fragile lectin was applied to unfixed rat eye. Following washing, biotinylated Dolichoε biflorus lectin (GalNAc-specific) was applied to the eye. The presence of biotinylated D. biflorus lectin was then assessed using streptavidin-peroxidase and 3',3- diaminobenzidine tetrahydrochloride (DAB).
The application of unlabelled C. fragile lectin to the eye, prior to the application of the labelled D. biflorus lectin, inhibited (blocked) binding of the labelled D. biflorus lectin as indicated by a complete absence of a brown precipitate (DAB) on the cornea or conjunctiva.
As a control, we demonstrated that direct application of labelled D. biflorus lectin to the eye, followed by detection with streptavidin-peroxidase DAB, gave an intense brown precipitate on the corneal and conjunctival surfaces.
2) Direct method
Biotinylated C. fragile lectin was applied to rat eyes. Binding was assessed with streptavidin-peroxidase DAB as above. Microscopical examination revealed the presence of a dense brown precipitate of DAB on the corneal and conjunctival surfaces. This investigation was repeated using various dilutions of the biotinylated C. fragile lectin. The intensity of the DAB brown precipitate on corneal and conjunctival surfaces was proportional to the concentration of the biotinylated C. fragile lectin used.
The GAlNAc-binding lectin from the green marine alga binds to the surfaces of rat cornea and conjunctiva and therefore has potential value in topical drug location in the eye. It is therefore believed that lectins derived from certain marine algae may be suitable agents for incorporation in topical drug delivery systems for the eye and mouth.
Example 4
The use of lectins as a method of extending drug therapy within the oral cavity
The aim of this study was to identify lectins that could be used to retain a dosage from within the oral cavity in order to prolong localised drug delivery or to enhance systemic drug absorption. This initial study investigated the binding to viable human buccal epithelial cells of a variety of different lectins. The method used was adapted from that described by Nicholls T.J. et al (1993) J. Phar . Pharmac. 45 1122. Human buccal cells were gently scrapped from the buccal surface with a wooden spatula which was then immersed in 10 ml of 0.05M tris buffered saline (TBS) pH 7.6. The cell suspension was filtered through a Nucleopore membrane filter, pore size 3μm. The filter and retained cells was immersed in 5 ml of lOmgL"1 biotinylated lectin (BL) in TBS, containing lmMCaCl2, for 30 min and washed twice at 5 min intervals in 0.05M TBS, before treating with 5mgL_1 streptavidin peroxidase (SP) in 0.125M TBS for 1 h. The filter was re-washed twice in 0.05M TBS and 0.015% (v/v) Hz02 for 7 min. The filter was counterstained with methyl green after soaking in 95% ethanol. Appropriate controls were completed omitting the SP, DAB or the lectin. The surface of the filter was examined using light microscopy at x400 magnification. The intensity of the DAB staining, indicating bound lectin, was evaluated subjectively using the following scoring: Strong staining (+++) intermediate staining (++), weak staining (+) and no staining (0).
Table 3
Lectin binding to human buccal epithelial cells (n-3)
Figure imgf000022_0001
All the lectins were seen to bind to varying degrees to buccal cells, as indicated by the brown precipitate of DAB (Table 3). The precipitate appeared to be fairly evenly distributed over the cell surface. Little or no staining was observed with the controls. It was observed that lectins of up to 50kD showed very good stain intensities. However the intensity of staining indicates the quantity of biotin present, and this depends on the molecular weight of the lectin and the lectin:biotin ratio, not only the extent of lectin binding, and this has to be considered when evaluation these staining intensity scores.
It may be concluded however that the lectins tested bind to unfixed buccal mucosal cells, and so may be used as a means of enhancing drug delivery to the oral cavity.
Some proposed formulations for the oral/vaginal cavities and the eye
As previously stated, it is proposed to use the lectins identified in the preceding studies as ' ligands' to anchor an appropriate drug for delivery to the mucosal surfaces of the eye, mouth, vagina or the respiratory tract. The delivery systems envisaged will be of the following types:
1) Lectin drug complexes in solution 2) Suspensions of microparticleε with attached lectins on the surface 3) Liposomal preparations containing lectins and an appropriate drug.
1) Solutions of lectins and drugs Lectin/ drug complexes Lectin as large macromolecules are likely to form complexes with a variety of drugs in solution, particularly cationic molecules like pilocarpine and chlorhexidine. Direct covalent binding of the drug to the lectin using, for example, the formation of weak ester linkages can be used. The lectin binding site can be protected using the appropriate sugar residue during this procedure. Lectins have been bound to a range of molecules using gluteraldehyde as a cross linking agent followed by affinity chromatography and gel filtration chromatography, without losing their activity (Shier W.T. Drug carriers in biology and medicine, ed. G Gregoriadis, Academic Press 1979, pp.43-70).
Lectin/ macromolecule/ drug complexes In this system an intervening polymer or macromolecule is included in the formulation as a spacer/carrier device. Any non-toxic water soluble polymer of a water soluble grade would be appropriate. Some possible formulations are described below.
Contents of a suitable formulation
(a) 2-5% of a carboxyl group containing polymer or macromolecule with low to medium viscosity grades (e.g. 6,000Da - 750,000Da polyacrylic acid), sodium carboxymethylcellulose, sodium alginate or sodium hyaluronate (the molar concentration of monomer units must be greatly in excess of the number of moles of added sugar and drug).
(b) 0.1 - 10 mM of an appropriate lectin (e.g. Pisum sativuum, Helix pomatia , Solarum tuberosum) .
(c) 0.1 - 10 mM of the sugar group specific for that lectin (e.g. glucose, N-acetyl neuraminic acid, N- acetyl glucosamine) .
(d) The drug (e.g. pilocarpine nitrate, chlorhexidine acetate) .
Method of preparation:
As described by Garcia Gonzalez et al (Int. J. Pharm. 100, 1993, 25-31) sugars will form esters with carboxyl group containing polymers on gentle heating. It is therefore proposed to use this principle in forming a sugar/polymer ester to which the lectin will attach. Dissolve the polymer into an appropriate quantity of water (pH adjusted to 2-4 using hydrochloric acid) add ImM of the appropriate sugar for the required lectin, apply gentle heat and leave for 24h to allow esterification to occur. Adjust the pH to 5-6 using sodium hydroxide solution so that the macromolecule carboxyl groups are predominantly in the ionised form. Add the cationic drug (chlorhexidine acetate or pilocarpine hydrochloride) to allow the formation of a complex based on electrostatic interactions, as described by Saettone et al. (Drug. Dev. Ind. Pharm. 15, 2475-2489 1989). For pilocarpine the required concentration would be 1-5% in the final solution. Add the lectin appropriate for that sugar and allow to interact. Dialyse exhaustively against distilled water to remove free drug. Adjust concentration to give required dose of drug (1-5%) .
Complexes of pilocarpine with polyacrylic acids and sodium hyaluronic acid have been reported to produce extended ocular delivery of pilocarpine, see Saettone et al. (1989) and the enhancement of this procedure using a lectin ligand should substantially improve this effect. Formulations should be made isotonic using sodium chloride, sterilised by autoclaving or filtration and a preservative (chlorocresol 0.05%, phenylmercuric nitrate 0.002%, benzalkonium chloride 0.01% or chlorhexidine acetate 0.01%) added.
It is logical to predict that a wide variety of cationic drugs can be delivered using this principle, and it is envisaged that an anionic drug could be used with a cationic polymer with appropriate modifications to this system. 2) Microparticles Lectin-drug microparticles
It has been demonstrated that microparticles on Concanavalin A can be produced using a standard procedure (e.g. water in oil emulsification followed by cross- linking, drying and filtering) by first blocking the sugar binding sites with methyl mannopyranoside, then cross-linking with glutaraldehyde (Pai, C. et al. J. Pharm. Sci. 81, 532-536, 1992). Continuous washing with cold acetate buffer will remove the bound sugar and Schiff base-linkages reduced with sodium cyanoborohydride. It may therefore be possible to introduce the drug directly into a lectin microparticle during the cross-linking process or afterwards by allowing the microparticles to swell in the presence of a concentrated solution of the drug. This system may be made isotonic with sodium chloride and an appropriate preservative added for ocular drug delivery. Similar formulations would be appropriate for the mouth and vagina.
Standard microparticles
The formulation of standard microparticles for drug delivery is well established and can be completed readily. The attachment of lectins to the surface of an albumen or gelatin/alginate microparticle of less than 5μιτι diameter using either physical absorption or a gluteraldehyde conjugation procedure would be straightforward. Lectins will physically adsorb onto activated charcoal and latex, and so would be expected to adsorb onto an appropriate microparticle with equivalent surface properties. An example would be cellulose acetate hydrogen phthalate latex onto which both pilocarpine HC1 is adsorbed. It has been reported that 2% pilocarpine loading in these suspensions can be obtained, and this will prolong drug delivery to the eye (Gurny R. , Pharm. Acta Helv. 56 130-132 1981). The physical adsorption of a lectin onto this system should be easily achieved which would prolong residence time within the precorneal region.
In the eye progesterone enclosed in a polycarbophil microparticle has been used to prolong drug delivery (Hui, H-W and Robinson, J.R. Int J. Pharm. 26, 1985, 203- 213). There is evidence that polyacrylic acid loses its adhiesve properties at the pH within the eye and so will be dislodged from the corneal surface. Therefore surface attachment of lectins would appear to offer a way of extending drug delivery. It is envisaged that this could be achieved by attaching the appropriate sugar to the microparticle surface by an esterfication procedure as described for solutions, and then suspending in a lectin solution to allow lectin surface binding. Excess lectin would be removed by filtering out the particles and washing. The dried microparticles can then be formulated into suspensions for drug delivery to the eye, mouth, vagina or nasal cavity.
3) Liposomes
The ophthalmic use of liposomes has been well reported in the literature e.g. to deliver triamcinolone acetonide (Singh K., Mezei, M. Int. J. Pharm. 16, 1993, 339-344) and pilocarpine HC1 (Benita S. et al., J. Microencapsulation 1, 1984, 203-216). The formulation and therapeutic effects of liposomes for local and systemic delivery of drugs has been well documented. The production of proteoliposomes containing a derivative of Concanavalin A has been reported (Francis S.E. et al. Biochimica et Biophyscia Act, 1062, 1991, 117-122). It would therefore seem reasonable to combine the two technologies to produce liposomes that will bind to ocular, oral and vaginal surfaces, using the lectins identified in our studies.

Claims

1. A drug delivery system comprising lectin and a pharmacologically active agent, wherein the active agent is releasably bound to the lectin.
2. The drug delivery system of claim 1, wherein the pharmacologically active agent is a pharmaceutical.
3. The drug delivery system of claim 1 or 2, wherein the lectin and the pharmacologically active agent are in a sterile isotonic vehicle.
4. The system of claim 3, wherein the pharmacologically active agent comprises an opthalmically active pharmaceutical.
5. A method of treatment of a bacterial, fungal, viral or allergic disorder which comprises the administration of a pharmacologically active agent to a patient suffering from such a disorder by the use of the drug delivery system as claimed in any of claims 1 to 4.
6. The method according to claim 5 wherein the pharmacologically active agent is administered to the eye.
7. The method according to claim 5 wherein the pharmacologically active agent is administered to a body cavity other than the eye.
8. The method according to claim 7 wherein the pharmacologically active agent is administered to the mouth or vagina.
9. Use of a lectin in the manufacture of a medicament in which a pharmacologically active agent is bound to the lectin.
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Cited By (3)

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Publication number Priority date Publication date Assignee Title
WO1997005267A2 (en) * 1995-07-26 1997-02-13 Maxim Pharmaceuticals Mucosal delivery of polynucleotides
EP0819008A1 (en) * 1995-05-30 1998-01-21 Lectin Biopharma, Inc. Method of using lectins for prevention and treatment of skin diseases and disorders
WO2003103717A1 (en) * 2002-06-11 2003-12-18 Cambridge Biotechnology Ltd Therapeutic conjugate consisting of a mek inhibitor and a targeting agent

Citations (1)

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WO1993000076A1 (en) * 1991-06-24 1993-01-07 Minnesota Mining And Manufacturing Company Carrier systems for drugs

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993000076A1 (en) * 1991-06-24 1993-01-07 Minnesota Mining And Manufacturing Company Carrier systems for drugs

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0819008A1 (en) * 1995-05-30 1998-01-21 Lectin Biopharma, Inc. Method of using lectins for prevention and treatment of skin diseases and disorders
EP0819008A4 (en) * 1995-05-30 2002-04-03 Lectin Biopharma Inc Method of using lectins for prevention and treatment of skin diseases and disorders
WO1997005267A2 (en) * 1995-07-26 1997-02-13 Maxim Pharmaceuticals Mucosal delivery of polynucleotides
WO1997005267A3 (en) * 1995-07-26 1997-04-24 Maxim Pharmaceuticals Mucosal delivery of polynucleotides
WO2003103717A1 (en) * 2002-06-11 2003-12-18 Cambridge Biotechnology Ltd Therapeutic conjugate consisting of a mek inhibitor and a targeting agent

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