Synergistic herbal ophthalmic formulation for lowering the intra ocular pressure in case of glaucoma

The present invention relates to a synergistic herbal composition for lowering the intra ocular pressure in different types of glaucoma and process for the preparation of the same in pharmaceutically acceptable dosage forms.

Glaucoma is a disease characterized by high intraocular pressure (IOP) sufficient to cause either temporary or permanent impairment of vision. The rise in IOP might be due to:

Increased rate of aqueous formation Decreased rate of out flow Raised pressure in the draining episcleral veins.

An obstruction to the circulation of the aqueous at the pupil or to its drainage through the angle of the anterior chamber causes glaucoma. The normal IOP of an individual ranges up to 20 mm Hg and can rise up to 60 to 70 mm of Hg in glaucoma patients. Raised IOP of this magnitude can result in loss of vision by causing damage to retinal nerve fibers. Optic nerve axons of the eyeball become compressed at the optic disc due to elevated IOP. This compression probably blocks the axonal flow of cytoplasm from the neuronal cell bodies in the retina to the extended optic nerve fibers entering the brain. It results in lack of nutrition of fibers and ultimately causes death of the neurons. Compression of retinal artery may increase the neuronal damage due to reduction in retinal nutrition.

Glaucoma is Generally Classified as

Primary

Developmental

Secondary

The commonest form of glaucoma is primary glaucoma; it can be:

Open Angle Glaucoma:

Angle of the anterior chamber is always open, at all stages of disease, and aqueous has access to the outflow channels at all times. There is increased resistance to outflow in the corneoscleral meshwork. IOP may be raised or elevated.

Angle Closure Glaucoma:

No abnormal resistance to outflow in the corneoscleral meshwork is observed. The sole cause of elevated tension is closure of the angle. The iris obstructs the access of aqueous humor to the outflow channels.

Magnitude of the Disease

Glaucoma is the third major cause of avoidable blindness. The global estimate of blindness is over 44 million with glaucoma accounting for more than 15% of the blind patients worldwide (2). Worldwide approximately two-thirds of all blind or visually impaired people are women (3). India has a high burden of blind (23.5%) in the world and 13% of the global blindness due to glaucoma is in India. Many population-based surveys carried out in the west and in Asia have shown that glaucoma remains undetected in nearly 50% of the cases and hence glaucoma related blindness and disability is often underestimated (4-5).

Prompt and effective management of glaucoma is necessary to reduce the incidence of cases of bilateral blindness due to progressive glaucoma. Biological revolution in medicine has provided new avenues for therapeutic intervention. Newer and innovative treatment strategies are being considered for the control of raised intraocular pressure (TOP) by the use of synthetic and herbal drugs in glaucoma.

Presently Available Glaucoma Therapy

The primary goal in the management of glaucoma is to lower IOP below 20 mm Hg in the patients with mild changes in the optic disc and below 15 mm Hg in the patients with more severe changes. Surgical intervention aiming at increasing the aqueous humor outflow is undertaken when IOP remains uncontrolled even with multiple drug therapy.

The following groups/drugs are widely used in the treatment of glaucoma:

Group of Drugs Formulations TOPICAL DRUGS Cholinergic agonists Pilocarpine, carbechol, physostigmine Adrenergic agonists Forskolin, isoproterenol, salbutamol, epinephrine Adrenergic antagonists Timolol, betaxolol, atenolol Prostaglandin analogues Latanoprost Carbonic anhydrase Trifluoromethazolmide, aminozolamide inhibitors SYSTEMIC DRUGS Carbonic anhydrase Acetazolamide, methazolamide, inhibitor dichlorphenamide Hyper- osmotic agents Glycerol, mannitol Miscellaneous Cannabinoids, prostaglandins, ACE inhibitors, melatonin, calcium channel blockers, haloperidol.

Drawbacks of the Presently Available Treatment

Synthetic drugs are currently available for the control of intraocular pressure (IOP) but have the drawbacks of being toxic, expensive and often have to be administered multiple times a day resulting in poor patient compliance. Thus, an inexpensive drug with potent ocular hypotensive effect and devoid of side effects with low frequency of application is desirable and its identification will be major achievement for human welfare. Medicinal plant based formulations are being used since long for a variety of diseases. Pilocarpine is one example of antiglaucoma drug of plant origin. A variety of substances of plant origin are known to have antichlolonergic and diuretic activity. Such drugs might be useful antiglaucoma drugs.

Following are the adverse reactions observed for synthetic drugs:

The object of the present invention is to develop herbal synergistic composition for its IOP lowering and anti glaucoma potential.

Another object of the present invention is to formulate the synergistic herbal composition in to pharmaceutically acceptable ophthalmic dosage form with optimum anti glaucoma activity.

Yet another object of the present invention is to overcome disadvantages associated with commonly used allopathic medicine for glaucoma.

Accordingly present invention provides a synergistic herbal composition for lowering IOP in glaucoma comprising synergistically effective amount of extract of herbs selected from Ocimum species, Curcuma species, Solanum nigrum and Areca catechu optionally along with a pharmaceutically acceptable excipient or carrier.

In synergistic herbal composition of the present invention, Ocimum species is selected from the group consisting of Ocimum basilicum, Ocimum canum, Ocimum kilimandscaricum, Ocimum sanctum, Ocimum viride and Curcuma species is selected from the group consisting of Curcuma longa, Curcuma avaleton, Curcuma amada, Curcuma aromatica Salisb.

A synergistic herbal composition of the present invention comprises:

A synergistic herbal composition of the present invention preferably comprises:

In the preferred embodiment, the synergistic herbal composition of the present invention preferably comprises Ocimum basilicum, Curcuma longa and Solanum nigrum.

In yet another preferred embodiment, the synergistic herbal composition of the present invention preferably comprises Ocimum basilicum, Curcuma longa and Areca catechu.

The use of the terms, “synergistic” and “synergistically effective,” are used in the present invention to mean a biological effect created from the application of two or more agents to produce a biological effect that is greater than the sum of the biological effects produced by the application of individual agents.

The synergistic herbal composition of the present invention optionally comprising the pharmaceutically acceptable excipients which are selected from the group comprising solubility enhancing agents such as polysorbate, cyclodextrin and their derivative, Cremophore RH 40 and other derivative, Viscosity increasing agents such as Hydroxy propyl methyl cellulose and other suitable cellulose derivative, poly vinyl alcohol, povidone, carbopol caragenin, etc, anti oxidants such as citric acid, EDTA and salts thereof, sodium metabisulphite and other approved water soluble anti oxidants, buffering agents such as citrate, borate, phosphate, citro phosphate and osmolarity adjusting agents such as sodium chloride, mannitol, glycerol, preservatives such as benzalkonium chloride, sorbic acid, methyl paraben, propyl paraben, and salts there of etc.

The synergistic herbal composition of the present invention is preferably formulated in the form of eye drop, ointment, cream, gel.

The present invention further comprises a process for preparing the said herbal formulation. The process of preparing the said herbal ophthalmic formulation comprises following steps:

i. Coarsely grinding the individual herb such as herein described and extracting it with solvents having different polarity selected from the group such as water, alcohol, acetone, ethyl acetate, Petroleum ether, chloroform or their mixture in different ratio; ii. Optionally concentrating the extract obtained in step (a) under vacuum and converting the same either in the form of thick paste having around 20-30% solids or in the form of dry powder; iii. Formulating pharmaceutically acceptable herbal composition by combining the extracts obtained in step (a) or step (b) in different ratios such as herein described to yield the synergistic herbal composition in the form of eye drop, ointment, cream or gel; iv. Alternatively the extraction can also be performed using distillation method and distillate can be directly used for formulating synergistic herbal composition such as herein described.

The invention is illustrated by the following examples which are not meant to restrict the scope of the invention in any manner

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined. In the examples, “part” and “parts” mean “part by weight” and “parts by weight”, respectively, unless otherwise specified.

The process for preparing the herbal composition comprises the following steps:

(i) Extraction of herb: The herbs are cleaned, coarsely ground and extracted with water using 8 times the amount of water by heating it to boil for 10 min. The extract is filtered and concentrated to a thick paste having around 30% of solid content. It is then dried in vacuum drier at a temperature of 60 C or it can also be spray dried or freeze dried. The dried powder is collected, packed after sieving in double poly bag. Alternatively herbs can be distilled and distillate can be used for further formulation development. (ii) The extracts as per formula are weighed and dissolved in water containing 0.25% HPMC as viscosity increasing agent under stirring. Additionally Cremophore RH 40 or its suitable derivative is added to increase the solubility. (iii) The preparation in centrifuged at about 4000 rpm for 30-60 min to remove the insoluble impurities. Alternatively it can be filtered using what man filter paper. (iv) To the clear filtrate suitable preservative (in this case, BKC, methyl and propyl paraben sodium and sorbic acid, phenyl ethyl alcohol and mercury containing preservatives are found to be suitable) are dissolved. (v) Disodium EDTA and sodium meta bisulphite as anti oxidants are dissolved in it by stirring (vi) Finally pH is adjusted with boric acid/borax, citric acid, sodium citrate, potassium and sodium phosphate to 5-7 and volume is made up with water for injection. (vii) The liquid is then filtered using Millipore filter of 0.22 micron and filled in plastic eye drops vial under laminar flow and labeled. (viii) The final product is clear, transparent having yellow to yellowish red color having osmolarity of 250-350 mosmol/kg and pH of 5-7.

The anti glaucoma activity of herbal ophthalmic solutions was evaluated in rabbits using following models of glaucoma:

1. Normotensive model: Twelve Albino rabbits of either sex weighing 1.5-2 kg were subjected for baseline IOP measurements using Non Contact Tonometer. The drug (50 ul) was then instilled into one of the eye while the other eye served as the control eye and was instilled with normal saline (50 ul). IOP was then recorded at 30-minute interval for a period of 6 hours. 2. Water loading model: Twelve Albino rabbits of either sex were fasted overnight. The baseline IOP was then recorded next morning and drug (50 ul) was instilled in the test eye and normal saline (50 ul) in control eye. 30 minutes later rabbits were anaesthetized by injecting thiopentone sodium (16 mg/kg BW) in the marginal ear vein. Infant feeding tube was then inserted into the stomach followed by injection of tap water (100 ml/kg) through the tube. IOP was now recorded every 15-min for a period of 120 minutes. The concentration of drug showing best effect in normotensive model was further tested in water loading model. This model mimics the acute glaucomatous attacks. 3. Steroid induced glaucoma model: 12 young rabbits were trained to accept tonometry and then IOP was measured daily for 15 days so as to make a record of baseline TOP. These rabbits were then instilled with prednisolone 1% eye drops (10 ul) in the test eye and normal saline (20 ul) in the control eye, twice a day for a period of 40 days. IOP was measured twice a week during steroid treatment period. At the end of 40 days rabbits were subjected to evaluation of antiglucoma activity. The concentration of drug showing best effect in normotensive model was further tested in steroid induced glaucoma model. TOP measurements were done every 30-minute for a period of 6 hours. This model mimics the chronic open angle glaucoma.

The different ophthalmic formulations were prepared using following formulas:

(i) Ocimum Basilicum Ophthalmic Formulation (F1) Comprises:

(ii) Curcuma longa Ophthalmic Formulation (F2) Comprises:

(iii) Solanum nigrum Ophthalmic Formulation (F3) Comprises:

(iv) Areca catechu Ophthalmic Formulation (F4) Comprises:

(v) Combined Ocimum basilicum, Curcuma Longa, Solanum Nigrum , ophthalmic formulation (F5) of the present invention comprises:

(vi) Combined Ocimum basilicum, Curcuma Longa, Areca Catechu Ophthalmic formulation (F6) of the present invention comprises:

Quantity for S. N. Ingredients 100 ml (mg) 1 Ocimum basilicum extract 500 2 Curcuma longa extract 100 3 Areca catechu extract 500 4 Hydroxy propyl methyl cellulose 250 5 Methyl paraben sodium 200 6 Propyl paraben sodium 20 7 Disodium EDTA 100 8 Sodium metabisulphite 100 9 Boric acid/borax quantity sufficient to pH 6.5 q.s. 10 Water for injection q.s. to volume q.s.

Manufacturing Procedure for Formulation (F1, F2, F3 and F4):

1. Hydroxy propyl methyl cellulose (HPMC) is dissolved in about 50 ml of water under stirring. Once it is dissolved completely, then main active ingredient as per above formula of Formulation (F1, F2, F3 and F4) are added to this and dissolved under stirring. 2. The solution is then centrifuged at 4000 rpm for 30 minutes and clear liquid is collected. 3. Methyl and propyl paraben sodium is dissolved in around 10 ml of water and added to clear filtrate of step 2 under stirring. 4. Item number 5 and 6 are then added and dissolved in main bulk under stirring and pH is checked 5. pH is then adjusted with dilute borax/boric acid solution and volume is made up. 6. The solution is filtered using 0.22 micron filter aseptically and product is filled in 10 ml three piece plastic vial.

Manufacturing Procedure for Formulation (F5 and F6):

1. Hydroxy propyl methyl cellulose (HPMC) is dissolved in about 50 ml of water under stirring. Once it is dissolved completely, then main active ingredient as per above formula of Formulation (F1, F2, F3 and F4) are added to this and dissolved under stirring. 2. The solution is then centrifuged at 5000 rpm for 30 minutes and clear liquid is collected. 3. methyl and propyl paraben sodium is dissolved in around 10 ml of water and added to clear filtrate of step 2 under stirring. 4. Item number 7 and 8 are then added and dissolved in main bulk under stirring and pH is checked. 5. pH is then adjusted with dilute borax/boric acid solution and volume is made up. 6. The solution is filtered using 0.22 micron filter aseptically and product is filled in 10 ml three piece plastic vial.

Results:

From the above results, surprisingly the herbal composition of the present invention comprising synergistic effective amount of Solanum nigrum, Curcuma longa, Ocimum basilicum (Formulation-F5) and Curcuma longa, Ocimum basilicum, Areca catechu (Formulation-F6) showed enhanced and surprising effects as compared to the individual formulations (F1, F2, F3 and F4). Therefore the said herbal composition (F5 and F6) are working synergistically.

For Formulating the Ophthalmic Drops

Quantity per S.N. Ingredients 100 ml 1 Solanum nigrum extract 250 mg 2 Ocimum basilicum extract 500 mg 3 Curcuma longa extract 100 mg 4 Hydroxy propyl methyl cellulose 250 mg 5 Cremophore RH 40 1000 mg  6 Methyl paraben sodium 200 mg 7 Propyl paraben sodium  20 mg 8 Disodium EDTA 100 mg 9 Sodium metabisulphite 100 mg 10 Citric acid 350 mg 11 Disodium hydrogen phosphate 900 mg 12 Sodium chloride 170 mg 13 Water for injection q.s.

Manufacturing Procedure:

1. Hydroxy propyl methyl cellulose (HPMC) is dissolved in about 50 ml of water under stirring. Cremophore RH 40 is added to this solution and dissolved under stirring. Once it is dissolved completely, then main active ingredient as per above formula (S. No. 1-3) are added to this and dissolved under stirring. 2. The solution is then centrifuged at 5000 rpm for 30 minutes and clear liquid is collected. 3. Methyl and propyl paraben sodium is dissolved in around 10 ml of water and added to clear filtrate of step 2 under stirring. 4. Item number 8 and 9 are then added and dissolved in main bulk under stirring and pH is checked. 5. Finally citric acid and sodium phosphate are added to bulk and volume is made up. 6. The solution is filtered using 0.22 micron filter aseptically and product is filled in 10 ml three piece plastic vial.

For Formulating the Gel