Description:FIELD OF THE INVENTION
[0001] The present disclosure generally relates to the field of pharmaceuticals. Specifically, it relates to an ocular drug delivery system comprising thiolated chitosan-coated proniosomes loaded with one or more therapeutic agents; and a method of preparing the same.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Glaucoma is a condition that damages optic nerves of the eyes. It is often linked to a buildup of pressure inside your eye. The increased pressure in eye, called intraocular pressure, can damage optic nerves, which send images to brain. If the damage worsens, glaucoma can cause permanent vision loss or even total blindness within a few years.
[0004] Glaucoma is second to cataract as a leading cause of global blindness and is the leading cause of irreversible visual loss. In 2002, 37 million individuals were blind worldwide, with glaucoma accounting for 12.3% of these individuals. By the year 2020, it is estimated that there will be almost 80 million people in the world with glaucoma. Bilateral blindness from glaucoma is projected to affect 8.4 million individuals worldwide by 2010 and greater than 11 million by 2020. Globally, glaucoma is a significant cause of vision loss. Glaucoma is a serious condition affecting the anterior chamber of the eye.
[0005] Normally aqueous humor is produced to nourish the anterior ocular tissues and drains through the trabecular meshwork and uveoscleral outflow. Imbalance occurs due to fluid overproduction or blockage of the drainage system leading to an accumulation of aqueous humor in the anterior chamber, this accumulation leads to an increase in the intraocular pressure (IOP). The elevation in IOP leads to an impairment in retinal blood flow, resulting in progressive degeneration of the optic nerve, causing gradual irreversible loss of vision.
[0006] Glaucoma symptoms include blurred vision, headache, hallows in vision, and progressive loss of vision. It is the most serious ocular condition requiring a lifetime treatment to prevent symptoms and progression of the condition.
[0007] Pharmacological treatment of glaucoma based on either decreasing production of aqueous humor or increasing its drainage to restore the balance and prevent the buildup of aqueous humor.
[0008] The field of polymer nanoparticles (PNPs) is quickly expanding and playing an important role in a wide spectrum of areas ranging from electronics, photonics, conducting materials, sensors, medicine, biotechnology, pollution control, and environmental technology. PNPs are promising vehicles for drug delivery by easy manipulation to prepare carriers with the objective of delivering the drugs to a specific target, such an advantage improves drug safety.
[0009] Polymer-based nanoparticles effectively carry drugs, proteins, and DNA to target cells and organs. Their nanometer size promotes effective permeation through cell membranes and stability in the bloodstream. Polymers are very convenient materials for the manufacture of countless and varied molecular designs that can be integrated into unique nanoparticles constructs with many potential medical applications.
[0010] Niosomes are vesicular structures formed of a bilayer of non-ionic surfactant molecules which contain an aqueous nucleus. Such structures, which are similar in formation and structure to liposomes, well-known vesicles formed of phospholipid molecules, can carry molecules having different features: hydrophilic molecules which can be entrapped in the aqueous nucleus and hydrophobic substances which can be connected to the bilayer.
[0011] However, niosomes also have certain limitations, like physical instability, aggregation, leakage of the entrapped drug, and the like. To overcome these disadvantages, proniosomes are prepared.
[0012] Contemplated herein is a proniosomal formulation for ocular delivery of therapeutic agents for treating various ocular conditions, preferably glaucoma.

OBJECTS OF THE INVENTION
[0013] In an embodiment, the present disclosure relates to a pharmaceutical formulation comprising a delivery system loaded with one or more therapeutic agents or a pharmaceutically acceptable salt thereof for ocular delivery.
[0014] An object of the present invention is to provide a pharmaceutical formulation comprising a therapeutic agent-loaded ocular delivery system.
[0015] An object of the present invention is to provide a therapeutic agent-loaded ocular delivery system, wherein the delivery system is a proniosome.
[0016] An object of the present invention is to provide a brimonidine-loaded ocular delivery system, wherein the delivery system is a proniosome.
[0017] An object of the present invention is to provide a therapeutic agent-loaded proniosome, wherein the proniosome is coated with a mucoadhesive agent.
[0018] An object of the present invention is to provide a therapeutic agent-loaded proniosome, wherein the proniosome is coated with modified chitosan.
[0019] An object of the present invention is to provide a therapeutic agent-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0020] An object of the present invention is to provide a brimonidine-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0021] Another object of the present invention is to provide a method for preparing a therapeutic agent-loaded proniosomes by coacervation phase separation method.
[0022] Another object of the present invention is to provide a method for preparing therapeutic agent-loaded proniosomes
[0023] Another object of the present invention is to provide a method for coating the therapeutic agent-loaded proniosomes with thiolated chitosan
[0024] Another object of the present invention is to provide a method for preparing brimonidine-loaded proniosomes.
[0025] Another object of the present invention is to provide a method for preparing a brimonidine-loaded proniosomes by coacervation phase separation method.
[0026] Another object of the present invention is to provide a method for coating the brimonidine-loaded proniosomes with thiolated chitosan.
[0027] Yet another object of the present invention is to increase the bioavailability of brimonidine by using thiolated chitosan-coated proniosomes during ocular delivery.
[0028] Yet another object of the present invention is to provide treatment of ocular disorders/conditions by brimonidine-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0029] Yet another object of the present invention is to provide a treatment system for glaucoma by brimonidine-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.

SUMMARY OF THE INVENTION
[0030] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0031] In an aspect, the present disclosure relates to a pharmaceutical formulation comprising a delivery system-loaded with one or more therapeutic agents or a pharmaceutically acceptable salt thereof for ocular delivery.
[0032] In an aspect, the present disclosure relates to a pharmaceutical formulation comprising a therapeutic agent-loaded ocular delivery system.
[0033] In an aspect, the present disclosure relates to a therapeutic agent-loaded ocular delivery system, wherein the delivery system is a proniosome.
[0034] In an aspect, the present disclosure relates to a brimonidine-loaded ocular delivery system, wherein the delivery system is a proniosome.
[0035] In an aspect, the present disclosure relates to a therapeutic agent-loaded proniosome, wherein the proniosome is coated with a mucoadhesive agent.
[0036] In an aspect, the present disclosure relates to a therapeutic agent-loaded proniosome, wherein the proniosome is coated with modified chitosan.
[0037] In an aspect, the present disclosure relates to a therapeutic agent-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0038] In an aspect, the present disclosure relates to brimonidine-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0039] In another aspect, the present disclosure relates to a method for preparing therapeutic agent-loaded proniosomes by coacervation phase separation method.
[0040] In another aspect, the present invention is to provide a method for preparing therapeutic agent-loaded proniosomes
[0041] In another aspect, the present invention is to provide a method for coating the therapeutic agent-loaded proniosomes with thiolated chitosan
[0042] In another aspect, the present invention is to provide a method for preparing brimonidine-loaded proniosomes.
[0043] In another aspect, the present invention is to provide a method for preparing brimonidine-loaded proniosomes by coacervation phase separation method.
[0044] In another aspect, the present invention is to provide a method for coating the brimonidine-loaded proniosomes with thiolated chitosan.
[0045] In yet another aspect, the present invention is to increase the bioavailability of brimonidine by using thiolated chitosan-coated proniosomes during ocular delivery.
[0046] In yet another aspect, the present invention is to provide treatment of ocular disorders/conditions by brimonidine-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0047] In yet another aspect, the present invention is to provide a treatment system for glaucoma by brimonidine-loaded proniosome, wherein the proniosome is coated with thiolated chitosan.
[0048] Other aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learnt by the practice of the invention.

DETAILED DESCRIPTION
[0049] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0050] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0051] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0052] In some embodiments, numbers have been used for quantifying weight percentages, angles, and so forth, to describe and claim certain embodiments of the invention and are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0053] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0054] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0055] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0056] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0057] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0058] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.
[0059] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0060] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0061] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0062] As described herein, the term “active agent” or “therapeutic agent” has the meaning known in the state of the art. The term denotes a pharmaceutical drug or compound that produces a desired biological activity in the body.
[0063] As described herein, the term “Proniosomes” has the meaning present in the state of the art. The term denotes-ionic based surfactant vesicles also known as “dry niosomes” because they may require hydration before drug release and permeation through the mucosa.
[0064] While a particular form of the invention has been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention.
[0065] The present disclosure generally relates to pharmaceutical formulations and processes of preparing the same for treating various medical conditions.
[0066] In an embodiment, the present disclosure relates to a pharmaceutical formulation comprising a delivery system loaded with therapeutic agent or a pharmaceutically acceptable salt thereof for ocular delivery.
[0067] In an embodiment, the present disclosure relates to a pharmaceutical formulation comprising a therapeutic agent-loaded ocular delivery system.
[0068] In an embodiment of the present disclosure, the ocular delivery system is selected from but not limited to nanoparticular system, microparticular system, liposomal system, vesicular system, niosomal system, proniosomal system, and the like. Preferably niosomal system. More preferably proniosomal system.
[0069] In an embodiment of the present disclosure, the therapeutic agent is selected for the treatment of ocular conditions including but not limited to cataract, optic nerve disorders including glaucoma, ocular hypertension, retinal disorders including retinitis, bulging eyes, macular degeneration, diabetic eye problems, conjunctivitis, inflammation including uveitis and the like. More preferably optic nerve disorders, including glaucoma.
[0070] In an embodiment of the present disclosure, the therapeutic agent is selected from but not limited to intraocular pressure-lowering agents such as prostaglandin compound, a prostaglandin receptor agonist, or a prostanoid receptor agonist; a beta-blocker; an alpha agonist; a carbonic anhydrase inhibitor; a cannabinoid receptor agonist; a Rho kinase inhibitor; a neurotrophic agent; a CNP; an NPR-B; a FAS inhibitor or a FASL inhibitor; or a combination thereof, in the manufacture of an ocular delivery system described herein for the treatment of glaucoma or ocular hypertension.
[0071] In an embodiment of the present disclosure, the therapeutic agent is selected from but not limited to bunazosin, timolol, nipradilol, latanoprost, bimatoprost, travoprost, dorzolamide, olopatadine, travoprost, bimatoprost, cyclosporin, brimonidine, moxifloxacin, tobramycin, brinzolamide, aciclovir timolol maleate, ketorolac tromethamine, prednisolone acetate, sodium hyaluronate, nepafenac, bromfenac, diclofenac, flurbiprofen, suprofenac, binoxan and the like. Most preferably brimonidine.
[0072] In an embodiment, the present disclosure relates to a therapeutic agent-loaded proniosome, wherein the proniosome is coated with a mucoadhesive agent.
[0073] In an embodiment, the present disclosure relates to a therapeutic agent-loaded proniosome, wherein the proniosome is coated with modified chitosan.
[0074] In an embodiment of the present disclosure, the modified chitosan comprises conjugated chitosan.
[0075] In an embodiment of the present disclosure, the modified chitosan comprises thiolated chitosan.
[0076] In an embodiment of the present disclosure, the thiolated chitosan shows better mucoadhesion with ocular mucin as compared to chitosan.
[0077] In an embodiment of the present disclosure, the proniosomes comprise niosomal bilayer formed from one or more non-ionic surfactants, cholesterol, and a stabilizer.
[0078] In an embodiment of the present disclosure, the proniosomes are non-ionic surfactant-based vesicles and are also known as “dry niosomes” because they may require hydration before drug release and permeation through the mucosa.
[0079] In an embodiment of the present disclosure, the non-ionic surfactant is selected from but not limited to Span 20 (Sorbitan monolaurate), Span 40 (Sorbitan monopalmitate), Span 60 (Sorbitan monostearate), Tween 20 (Polyoxyethylene sorbitan monolaurate), Tween 60 (Polyoxyethylene sorbitan monostearate), Tween 80 (Polyoxyethylene sorbitan monooleate), and Span 85 (Sorbitan trioleate). Most preferably Span 60.
[0080] In a preferred embodiment of the present disclosure, the stabilizer is lecithin.
[0081] In another embodiment of the present disclosure, the proniosomes is prepared by slurry method, slow spray coating method, or Coacervation phase separation method. Most preferably Coacervation phase separation method.
[0082] In an embodiment of the present disclosure, the thiolated chitosan is prepared by mixing chitosan, EDC (1-Ethyl-3-[3-dimethylami-nopropyl]-carbodiimide hydrochloride), NHS (N-hydroxy succinimide) and L-Cysteine HCl monohydrate at a pH of 6, followed by magnetic stirring for 24 h at 25 deg C.
[0083] In another embodiment of the present disclosure, a method for preparing therapeutic agent-loaded proniosomes comprises the steps of:
a. mixing therapeutic agent, surfactant, and cholesterol in presence of a stabilizer;
b. adding an organic solvent to the mixture from step a, followed by warming the composition from 60 to 70 deg C until the surfactant and cholesterol are fully dissolved;
c. adding an aqueous phase to the composition from step b, followed by warming the composition from 60 to 70 deg C until a clear solution is obtained; and
d. Cooling the composition from step c at room temperature to receive a proniosomal composition.
[0084] In another embodiment of the present disclosure, the therapeutic agent-loaded proniosomes are coated with thiolated chitosan.
[0085] In another embodiment of the present disclosure, a method for coating the therapeutic agent-loaded proniosomes comprises the steps of:
a. mixing the therapeutic agent-loaded proniosomes and thiolated chitosan, followed by stirring 60 min;
b. ultracentrifugation to remove un-coated thiolated chitosan in supernatant solution; and
c. harvesting the precipitate comprising thiolated chitosan-coated proniosomes loaded with a therapeutic agent.
[0086] In an embodiment of the present disclosure, the therapeutic agent is selected from but not limited to bunazosin, timolol, nipradilol, latanoprost, bimatoprost, travoprost, dorzolamide, olopatadine, travoprost, bimatoprost, cyclosporin, brimonidine, moxifloxacin, tobramycin, brinzolamide, aciclovir timolol maleate, ketorolac tromethamine, prednisolone acetate, sodium hyaluronate, nepafenac, bromfenac,diclofenac, flurbiprofen, suprofenac, binoxan and the like. Most preferably brimonidine.
[0087] In a preferred embodiment of the present disclosure, the thiolated chitosan-coated proniosome is loaded with brimonidine.
[0088] In a preferred embodiment of the present disclosure, the thiolated chitosan-coated proniosome shows electrostatic attraction with mucin, because the positively charged backbone of thiolated chitosan has the ability to show better mucoadhesion because of negatively charged mucosa present on the corneal surface.
[0089] In preferred embodiment of the present disclosure, a method for preparing brimonidine-loaded proniosomes comprises the steps of:
a. mixing brimonidine, Span 60, and cholesterol in presence of a lecithin;
b. adding an organic solvent to the mixture from step a, followed by warming the composition from 60 to 70 deg C until the surfactant and cholesterol are fully dissolved;
c. adding an aqueous phase to the composition from step b, followed by warming the composition from 60 to 70 deg C until a clear solution is obtained; and
d. Cooling the composition from step c at room temperature to receive a proniosomal composition.
[0090] In a preferred embodiment of the present disclosure, the brimonidine-loaded proniosomes are coated with thiolated chitosan.
[0091] In a preferred embodiment of the present disclosure, a method for coating the brimonidine-loaded proniosomes comprises the steps of:
a. mixing the brimonidine-loaded proniosomes and thiolated chitosan, followed by stirring 60 min;
b. ultracentrifugation to remove un-coated thiolated chitosan in supernatant solution; and
c. harvesting the precipitate comprising thiolated chitosan-coated proniosomes loaded with brimonidine.
[0092] In an embodiment, the present disclosure relates to proniosomal formulation comprising brimonidine in weight of at least 1 mg, at least 2 mg, at least 3 mg, at least 4 mg, at least 5 mg, at least 6 mg, at least 7 mg, at least 8 mg, at least 9 mg, at least 10 mg, at least 20 mg, at least 25 mg, at least 30 mg, at least 50 mg. More preferably at least 5-10 mg.
[0093] In an embodiment, the proniosomal formulation may be formulated as a topical dosage form selected from the group comprising hydrogel, ocular inserts, ocular discs, ocular implants, powder, reconstitutable powder, granule, gel, microparticles, nanoparticles, and the like. More preferably gels and granules.
[0094] In one embodiment, proniosomes comprise particle size is in the range 10 nm to 5000 nm, such as 10 to 500 nm, particularly 100 or 300 nm, for example, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% such as at least 99% of the particles are the relevant size or within said range. Thus in one embodiment of the invention at least 95%, at least 98%, or at least 99% of the particles of the pharmaceutical composition have a diameter of between 10 and 500 nm. In another embodiment at least 95%, at least 98%, or at least 99% of the particles of the pharmaceutical composition have a diameter of between 100 and 300 nm.
[0095] In one embodiment the proniosomal formulation does not contain particles higher than 1000 nm in diameter.
[0096] In an embodiment of the present disclosure, the pharmaceutical formulation may further comprise additional active ingredient(s) selected from one or more of group consisting of: ace-inhibitors, anti-Alzheimer's agents, antianginal drugs, anti-arrhythmias, anti-asthmatics, anti-cholesterolemics, analgesics, anesthetics, anti-convulsants, anti-depressants, anti-diabetic agents, anti-diarrhea preparations, antidotes, anti-emetics, anti-histamines, anti-hypertensive drugs, anti-inflammatory agents, anti-lipid agents, anti-manics, anti-migraines, anti-nauseants, anti-stroke agents, anti-thyroid preparations, anti-tumor drugs, anti-viral agents, acne drugs, alkaloids, amino acid preparations, anti-tussives, anti-uricemic drugs, anti-viral drugs, anabolic preparations, systemic and non-systemic anti-infective agents, anti-neoplastics, anti-parkinsonian agents, anti-rheumatic agents, anxiolytics, anti-psychotics, appetite stimulants, biological response modifiers, blood modifiers, bone metabolism regulators, bronchodilators, cardiovascular agents, central nervous system stimulates, cholinesterase inhibitors, contraceptives, decongestants, dietary supplements, dopamine receptor agonists, endometriosis management agents, enzymes, erectile dysfunction agents, fertility agents, gastrointestinal agents, H2-antagonists, homeopathic remedies, hormones, hypercalcemia and hypocalcemia management agents, immunomodulators, immunosuppressives, migraine preparations, motion sickness treatments, muscle relaxants, non-steroidal anti-inflammatories (NSAID's), obesity management agents, osteoporosis preparations, oxytocics, parasympatholytics, parasympathomimetics, prostaglandins, psychotherapeutic agents, respiratory agents, sedatives, serotonin 5-HT3 receptor antagonists, smoking cessation aids, sympatholytics, tremor preparations, urinary tract agents, vasodilators, laxatives, antacids, ion exchange resins, anti-pyretics, appetite suppressants, expectorants, anti-anxiety agents, anti-ulcer agents, anti-inflammatory substances, coronary dilators, cerebral dilators, peripheral vasodilators, psycho-tropics, stimulants, anti-hypertensive drugs, vasoconstrictors, migraine treatments, antibiotics, tranquilizers, anti-psychotics, anti-tumor drugs, anti-coagulants, anti-thrombotic drugs, hypnotics, anti-emetics, anti-nauseants, anti-convulsants, neuromuscular drugs, hyper- and hypo-glycemic agents, thyroid and anti-thyroid preparations, diuretics, anti-spasmodics, anti-obesity drugs, erythropoietic drugs, anti-asthmatics, cough suppressants, mucolytics, DNA and genetic modifying drugs, and combinations thereof.
[0097] In an embodiment of the present disclosure, the proniosomal formulation further comprises at least one pharmaceutically acceptable excipient.
[0098] In an embodiment of the present disclosure, the pharmaceutically acceptable excipients include but are not limited to, binders, diluents, thickeners, flow agents, absorbents, disintegrants, super disintegrants, preservatives, emulsifiers, tastemakers, stabilizers, sugars, anti-foaming agents, anti-caking agents, lubricants, coloring agents, coating materials, and combinations thereof. The excipients may be selected from those well known in the art.
[0099] In an embodiment of the present disclosure, the proniosomal formulation can be formulated in other dosage forms, including, liquids, suspensions, semi-solids, solutions, syrups, gels, emulsions, and the like. Most preferably semisolids, or gel.
[00100] In another embodiment, the present disclosure relates to a method of treatment, amelioration, or prevention of one or more ocular conditions by administering the pharmaceutically effective amount of the proniosomal formulation comprising Brimonidine or pharmaceutically active salts thereof.
[00101] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
[00102] In an embodiment, the pharmaceutical composition of the present invention maybe used in any manner known to a person skilled in the art.

EXAMPLES
[00103] The present disclosure is further explained in the form of following examples. However, it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.
[00104] Example 1: Preparation Of Brimonidine-Loaded Proniosomes By Coacervation Phase Separation Method.
Lecithin, Span 60, Cholesterol and pure drug Brimonidine were mixed in specified quantity in 2.5 ml of ethyl alcohol (95%) and kept on water bath with frequent stirring for 30 min. The temperature of above mixture is maintained at 70 to 80 deg C until complete lipid dissolution occurs. In another beaker, Phosphate buffer saline (pH ˜ 7.4) was prepared using NaCl, KCl, Na2HPO4 and KH2PO4 in specified quantity. The temperature of above mixture is maintained at 70 to 80 deg C. This solution is added to the prepared drug lipid mixture with slow shaking in clockwise direction to result in proniosomes.
[00105] Example 2: Coating of brimonidine-loaded proniosomes with thiolated chitosan:
10 mg of thiolated chitosan added in 10 ml of distilled water (1%W/V). The said 10 ml solution is added dropwise, in already prepared proniosomal clear solution with continuous magnetic stirring of 500 rpm for 60 mins. Excess polyelectrolytes and drug were then removed by ultracentrifugation at 20,000 rpm for 30 min. The mixture left to cool down to room temperature for 24 h and the white creamy proniosomal gel was formed.

ADVANTAGES OF THE PRESENT INVENTION
[00106] The present disclosure provides a proniosome formulation comprising a therapeutic agent or pharmaceutically active salts thereof that satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
[00107] The present disclosure provides a proniosome formulation that simple preparation method, less time consuming, and no special equipment is required.
[00108] The present disclosure provides a proniosome formulation that has a nano-size range that can be helpful to increase the stability of any volatile pharmaceutical agents, easily and cheaply fabricated in large quantities by a multitude of methods.
[00109] The present disclosure provides a proniosome formulation comprising biodegradable materials for nanoparticle preparation, allows sustained drug release at the targeted site after injection over a period of days or even weeks.
[00110] The present disclosure provides a proniosome formulation solves the physical instability issues as aggregation, fusion and, leakage.
[00111] The present disclosure provides a proniosome system that can be used for entrapping both hydrophobic and hydrophilic drug with higher entrapment efficiency.
[00112] The present disclosure provides a proniosome system that can be effectively stored at room temperature and the drug leakage from the proniosome vesicles was reduced which is the main concern with niosomes when stored at room temperature.
[00113] The present disclosure provides a proniosome formulation that reduces dose-related toxicity and increases efficacy.
[00114] The present disclosure provides a thiolated chitosan-coated proniosome formulation that has better mucoadhesion with ocular mucin as compared to chitosan.
[00115] The present disclosure provides a thiolated chitosan-coated proniosome formulation that has a special ability to unlock the tight junctions present in between different corneal epithelial cells.
[00116] The present disclosure provides a thiolated chitosan-coated proniosome formulation, wherein thiolated chitosan is considered of having antifungal and antibacterial properties.
, Claims:1. A proniosomal gel formulation, said formulation comprises a therapeutic agent-loaded ocular delivery system comprising therapeutic agent-loaded proniosomes coated with modified chitosan, wherein the proniosomes comprise niosomal bilayer formed a non-ionic surfactant, cholesterol, and a stabilizer.
2. The formulation as claimed in claim 1, wherein the therapeutic agent is selected from the group consisting of bunazosin, timolol, nipradilol, latanoprost, bimatoprost, travoprost, dorzolamide, olopatadine, travoprost, bimatoprost, cyclosporin, brimonidine, moxifloxacin, tobramycin, brinzolamide, aciclovir timolol maleate, ketorolac tromethamine, prednisolone acetate, sodium hyaluronate, nepafenac, bromfenac, diclofenac, flurbiprofen, suprofenac, binoxan and combinations thereof.
3. The formulation as claimed in claim 1, wherein the therapeutic agent is brimonidine in an amount of 5-10 mg.
4. The formulation as claimed in claim 1, wherein the modified chitosan is thiolated chitosan.
5. The formulation as claimed in claim 1, wherein the non-ionic surfactant is Span 60 and the stabilizer is lecithin.
6. A method of preparing the proniosomal gel formulation as claimed in claim 1 by coacervation phase separation method, said method comprises the steps of:
a. mixing therapeutic agent, surfactant, and cholesterol in presence of a stabilizer;
b. adding an organic solvent to the mixture from step a, followed by warming the composition from 60 to 70 deg C until the surfactant and cholesterol are fully dissolved;
c. adding an aqueous phase to the composition from step b, followed by warming the composition from 60 to 70 deg C until a clear solution is obtained;
d. cooling the composition from step c) at room temperature to obtain the therapeutic agent-loaded proniosomes; and
e. coating the therapeutic agent-loaded proniosomes with modified chitosan.
7. The method as claimed in claim 5, wherein the step e) comprises the steps of:
a. mixing the therapeutic agent-loaded proniosomes and thiolated chitosan, followed by stirring 60 min;
b. ultracentrifugation to remove un-coated thiolated chitosan in supernatant solution; and
c. harvesting the precipitate comprising modified chitosan-coated proniosomes loaded with the therapeutic agent.
8. A method of preparing proniosomal gel formulation comprising thiolated chitosam-coated proniosomes loaded with brimonidine by coacervation phase separation method, said method comprises the steps of:
a. mixing brimonidine, Span 60, and cholesterol in presence of a lecithin;
b. adding an organic solvent to the mixture from step a, followed by warming the composition from 60 to 70 deg C until the surfactant and cholesterol are fully dissolved;
c. adding an aqueous phase to the composition from step b, followed by warming the composition from 60 to 70 deg C until a clear solution is obtained; and
d. cooling the composition from step c at room temperature to receive a proniosomal composition; and
e. coating the brimonidine-loaded proniosomes with thiolated chitosan.
9. The method as claimed in claim 8, wherein the step e) comprises the steps of:
a. mixing the brimonidine-loaded proniosomes and thiolated chitosan, followed by stirring 60 min;
b. ultracentrifugation to remove un-coated thiolated chitosan in supernatant solution; and
c. harvesting the precipitate comprising thiolated chitosan-coated proniosomes loaded with brimonidine.
10. The method as claimed in anyone of claims claim 6-9, wherein the thiolated chitosan is prepared by mixing chitosan, EDC (1-Ethyl-3-[3-dimethylami-nopropyl]-carbodiimide hydrochloride), NHS (N-hydroxy succinimide) and L-Cysteine HCl monohydrate at a pH of 6, followed by magnetic stirring for 24 h at 25 deg C.