FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
The Patents Rules, 2003
PROVISIONAL SPECIFICATION
(See section 10 and rulel3)
1. TITLE OF THE INVENTION:
"LOW DOSE PHARMACEUTICAL COMPOSITION"
2. APPLICANT:
(a) NAME: CIPLA LTD.
(b)NATIONALITY: Indian Company incorporated under the Companies Act, 1956
(c) ADDRESS: 289, Bellasis Road, Mumbai Central, Mumbai - 400 008, Maharashtra, India
3.PREAMBLE TO THE DESCRIPTION:
The following specification describes the invention.

FIELD OF INVENTION:
The present invention relates to novel low dose pharmaceutical dosage form comprising antiviral drug. The present invention also provides process of preparing such dosage form and therapeutic methods of using such dosage form.
BACKGROUND OF INVENTION:
Influenza is a common condition affecting all age groups. It occurs mainly during the winter months and causes significant morbidity and increased mortality. The elderly and those with pre-existing medical problems, such as heart disease and renal disease, are particularly at the risk of suffering severe disease or developing complications.
Neuraminidase inhibitors are a class of antiviral drugs targeted at the influenza virus, which work by blocking the function of the viral neuraminidase protein, thus preventing the virus from reproducing by budding from the host cell.
Zanamivir is a selective inhibiter of neuraminidase, an enzyme that cleaves sialic acid from host and viral cell surfaces and thereby facilitates the release of progeny virus from
Zanamivir is the first neuraminidase inhibitor to be developed commercially, and it is used in the treatment of and prophylaxis of both Influenza virus A and Influenza virus B. The chemical name of zanamivir is 5(acetylamino)-4-[(aminoiminomethyJ)-amino]-2, 6-anhydro-3,4, 5-trideoxy-D-glycero-D-galactonon-2-enonic acid.


infected host cells. Zanamivir also prevents neuraminidase from cleaving sialic acid from the host cells by blocking the active site of neuraminidase. The resultant binding of viral hemagglutinin to the uncleaved sialic acid hinders release of nascent viruses from the host cell and causes them to clump at the host cell surface, with a net reduction in the amount of active virus.
Zanamivir has been approved for treatment and prophylaxis of illness due to influenza A and B virus in adults and pediatric patients. Zanamivir is administered by oral inhalation. This mode of administration delivers drug directly to the pulmonary site of influenza infection and minimizes systemic exposure.
The recommended therapeutic dose of zanamivir for treatment of influenza, in adults and pediatric patients 10 mg twice daily for 5 days. Further, the recommended therapeutic dose of zanamivir for prophylaxis of influenza in adults and pediatric patients in a household setting is 10 mg twice daily for 10 days and the recommended therapeutic dose of zanamivir for prophylaxis of influenza in adults and pediatric patients in a community setting is 10 mg once daily for 28 days.
EP0764023 discloses administration of zanamivir by mouth via inhalation or insufflation.
JP2002241310 discloses locally applicable compositions in the form of nasal drops and inhalants containing influenza virus inhibitors such as zanamivir.
CN101229122 discloses formulations of zanamivir in situ gel with advantages of high local concentration in respiratory, long drug detention time, high bioavailability, good adaptability for patients, and no toxicity.
CN101773468 discloses nasal nanoscale suspensions of zanamivir with advantages of low dosage, long action time, and good curative effects.
CN101773491 discloses zanamivir inhalable solution.

Various formulations that are disclosed and that are available in the market contain a dose of 5 mg of zanamivir for twice a day administration However, no composition is yet available which includes low dose zanamivir, wherein the total daily dose of zanamivir is less than the conventionally administered daily dose of at least about 10 mg of zanamivir, and which is still effective for the treatment of influenza.
Hence, there still exists a need to develop pharmaceutical compositions comprising low dose of zanamivir, wherein the total daily dose of zanamivir is less than the conventionally administered daily dose of at least about 10 mg of zanamivir, which also does not require the use of any specific bioenhancer and which can release the drug in a desired manner and in a quantity sufficient to alleviate desired pathological conditions without causing or at least minimizing dose related toxicity, and can be prepared in an easy and cost-effective manner.
OBJECT OF THE INVENTION:
An object of the present invention objective of the present invention is to provide novel low dose pharmaceutical dosage form comprising zanamivir along with one or more pharmaceutically acceptable excipient(s).
Another object of the present invention is to provide novel low dose pharmaceutical dosage form comprising zanamivir wherein the total daily dose of zanamivir is less than the conventionally administered daily dose of at least about 10 mg of zanamivir.
Yet another object of the present invention is to provide a process for preparing the pharmaceutical composition comprising a low dose of zanamivir for administration in the treatment or prophylaxis of influenza.

A further object of the present invention is to provide a method for treatment or prophylaxis of influenza which comprises administering a pharmaceutical composition comprising low dose of zanamivir.
SUMMARY OF THE INVENTION:
According to one aspect of the present invention, there is provided a pharmaceutical composition comprising low dose of zanamivir.
According to another aspect of the present invention there is provided a process for preparing the pharmaceutical composition comprising low dose of zanamivir.
According to yet another aspect of the present invention there is provided a pharmaceutical composition comprising low dose zanamivir for use in the treatment or prophylaxis of influenza.
DETAILED DESCRIPTION OF THE INVENTION:
Zanamivir has been administered conventionally by oral inhalation as 5 mg twice a day for the treatment and prophylaxis of illness due to influenza A and influenza B.
The inventors of this invention have made an effort to lower the dose of zanamivir and which can also be effectively administered for the treatment and prevention of influenza. Furthermore, the low dose compositions have improved bioavailability, and are easy to formulate. Further, such novel compositions require lesser quantity of excipients as compared to the conventionally available dosage form, which in turn leads to better patient acceptability. Preferably, the compositions of the present invention do not require the use of any specific bioenhancer or the like.

The term 'low dose' as used herein refers to the therapeutically effective dose of zanamivir which is less than the usual or the conventional dose required to produce the therapeutic effect.
The term "Zanamivir" is used in broad sense to include not only "Zanamivir" per se but also their pharmaceutically acceptable salts, pharmaceutically acceptable solvates, pharmaceutically acceptable hydrates, pharmaceutically acceptable esters, pharmaceutically acceptable enantiomers, pharmaceutically acceptable derivatives, pharmaceutically acceptable polymorphs, pharmaceutically acceptable prodrugs, pharmaceutically acceptable complexes etc.
The present invention provides novel low dose pharmaceutical dosage form compositions comprising zanamivir or its pharmaceutically acceptable salts, esters, prodrugs, solvates, hydrates, or derivatives thereof, along with one or more pharmaceutically acceptable excipient(s).
The pharmaceutical composition, according to the present invention, may comprise low dose zanamivir with one or more pharmaceutically acceptable excipients.
The pharmaceutical composition, according to the present invention, preferably may be administered once a day or twice a day in a dose which is less than the conventionally administered dose, which is about 5 mg of zanamivir twice a day.
According to an embodiment of the present invention provides a novel low dose pharmaceutical composition comprising zanamivir wherein the dose of the zanamivir is in a range of 3 mg to 8 mg, for once a day administration, or for twice a day administration, and wherein the total daily dose of zanamivir is less than the conventionally administered daily dose of at least about 10 mg of zanamivir.

The pharmaceutical composition, according to the present invention, may exhibit bioavailability to an extent to produce the desired pharmacological effects along with reduced side effects after dosing in a subject.
The pharmaceutical composition, according to the present invention may be used for the treatment or prophylaxis of viral diseases caused by orthomyxoviruses and paramyxoviruses such as, but not limited to, influenza A and B, parainfluenza, mumps, and Newcastle disease, fowl plaque and Sendai virus.
The pharmaceutical composition, of the present invention, may be administered by any suitable methods used for delivery of the drugs to the respiratory tract. The composition of the present invention may thus be administered as metered dose inhalers (MDI), dry powder inhalers (DPI), nebuliser, nasal spray, nasal drops, insufflation powders.
The various dosage forms according to the present invention may comprise carriers/excipients suitable for formulating the same.
According to one embodiment the pharmaceutical composition of the present invention may be administered by a dry powder inhaler (DPI).
The pharmaceutically acceptable excipients suitable for dry powder inhalation according to the present invention may be selected from suitable carriers which include but are not limited to sugars such as glucose, saccharose, lactose and fructose, starches or starch derivatives, oligosaccharides such as dextrins, cyclodextrins and their derivatives, polyvinylpyrrolidone, alginic acid, tylose, silicic acid, cellulose, cellulose derivatives (for example cellulose ether), sugar alcohols such as mannitol or sorbitol, calcium carbonate, calcium phosphate, etc. lactose, lactitol, dextrates,, dextrose, maltodextrin, saccharides including monosaccharides, disaccharides, polysaccharides; sugar alcohols such as arabinose, ribose, mannose, sucrose, trehalose, maltose, dextran.

The pharmaceutical, composition according to the present invention, may be included in suitable containers provided with means enabling the application of the contained formulation to the respiratory tract.
The powder for inhalation intended to be used for DPI may either be encapsulated in capsules of gelatin or hydroxypropyl methylcellulose or in blisters or alternatively, the dry powder may be contained as a reservoir either in a single dose or multi-dose dry powder inhalation device.
According to one embodiment the pharmaceutical composition of the present invention for inhalation intended to be used as a DPI may be administered via Revolizer™
Alternatively, the powder for inhalation intended to be used for DPI may be suspended in a suitable vehicle and packed in an aerosol container along with suitable propellants or mixtures thereof.
Further, the powder for inhalation intended to be used for DPI may also be dispersed in a suitable gas to form an aerosol composition.
According to another embodiment the pharmaceutical composition of the present invention may be administered by a metered dose inhaler (MDI).
The metered dose inhalers, according to the present invention, may comprise one or more pharmaceutically acceptable excipients as hydrofluoroalkane (HFC/HFA) propellants, co-solvents, bulking agents, non volatile component, buffers/pH adjusting agents, surface active agents, preservatives, complexing agents, or combinations thereof.
Propellants are those which, when mixed with the cosolvent(s), form a homogeneous propellant system in which a therapeutically effective amount of the active can be dissolved. The hydrofluoroaikane HFC/HFA propellant must be toxicologically safe and must have a vapor pressure which is suitable to enable the medicament to be administered via a pressurized MDI.

According to the present invention, the HFC/HFA propellants may comprise, one or more of 1,1,1,2-tetrafluoroethane (HFC-134(a)) and 1,1,1,2,3,3,3,-heptafluoropropane (HFC-227), HFC-32 (difluoromethane), HFC-143(a) (1,1,1-trifluoroethane), HFC-134 (1,1,2,2-tetrafluoroethane), and HFC-152a (1,1-difluoroethane) and such other propellents which may be known to the person having a skill in the art.
Co-solvent is any solvent which may be volatile or non-volatile, which is miscible in the formulation in the amount desired and which, when added provides a formulation in which the medicament can be dissolved. The function of the cosolvent is to increase the solubility of the medicament and the excipients in the formulation.
According to the present invention, the volatile and non-volatile co-solvent may comprise one or more of, C2- C6 aliphatic alcohols, such as but not limited to ethyl alcohol and isopropyl alcohol; glycols such as but not limited to propylene glycol, polyethylene glycols, polypropylene glycols, glycol ethers, and block copolymers of oxyethylene and oxypropylene; and other substances, such as but not limited to polyoxyethylene alcohols, and polyoxyethylene fatty acid esters; hydrocarbons such as but not limited to n-propane, n-butane, isobutane, n-pentane, iso-pentane, neo-pentane, and n-hexane; and ethers such as but not limited to diethyl ether, monosaccharides such as but not limited to glucose, arabinose; disaccharides such as lactose, maltose; oligosaccharides and polysaccharides such as but not limited to dextrans; polyalcohol such as but not limited to glycerol, sorbitol, mannitol, xylitol; salts such as but not limited to potassium chloride, magnesium chloride, magnesium sulphate, sodium chloride, sodium citrate, sodium phosphate, sodium hydrogen phosphate, sodium hydrogen carbonate, potassium citrate, potassium phosphate, potassium hydrogen phosphate, potassium hydrogen carbonate, calcium carbonate and calcium chloride.
Suitable buffers or pH adjusting agents may be employed in the aerosol solution formulation of the present invention.

According to the present invention, the buffer or the pH adjusting agent may comprise one or more of organic or inorganic acids such as but not limited to citric acid, ascorbic acid, hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid.
Suitable preservatives may be employed in the aerosol solution formulation of the present invention to protect the formulation from contamination with pathogenic bacteria.
According to the present invention, the preservative may comprise one or more of benzalkonium chloride, benzoic acid, benzoates such as sodium benzoate and such other preservatives which may be known to the person having a skill in the art.
Suitable complexing agents may be employed in the aerosol solution formulation of the present invention which is capable of forming complex bonds.
According to the present invention, the complexing agent may comprise one or more of but not limited to sodium EDTA or disodium EDTA.
Suitable surfactants may be employed in the aerosol solution formulation of the present invention which may serve to stabilize the solution formulation and improve the performance of valve systems of the metered dose inhaler.
According to the present invention, the surfactant may comprise one or more ionic and/or non- ionic surfactant, but not limited to oleic acid, sorbitan trioleate, lecithin, isopropylmyristate, tyloxapol, polysorbates such as polysorbate 80, vitamin E-TPGS, and macrogol hydroxystearates such as macrogol-15-hydroxystearate.
According to a further embodiment the pharmaceutical composition of the present invention may be administered by nebulization.
The nebulizer, according to the present invention may comprise may comprise suitable excipients such as tonicity agents, pH regulators, chelating agents in a suitable vehicle.

It may be well acknowledged to a person skilled in the art that the said pharmaceutical composition, according to the present invention, may further comprise one or more active in particular antibiotics, anti-bacterial and anti-viral agents such as those used to treat respiratory infections.
For example, other compounds effective against influenza viruses, such as but not limited to, amantadine, rimantadine, acyclovir, azidothymidine, vidarabine, ribavirin, dapsone, chloramphenicol, neomycin, cefaclor, cefadroxil, cephalexin, erythromycin, clindamycin, lincomycin, amoxicillin, ampicillin, carbenicillin, methicillin, nafcillin, penicillin, polymyxin, tetracycline, amphotericin-b, candicidin, lucensomycin, mepartricin, natamycin, nystatin, griseofulvin, oligomycins, neomycin tubercidin, picloxacillin, penicllins, sulfonamides, cephalosporins, quinolones, or their pharmaceutically acceptable salts, solvates, tautomers, derivatives, enantiomers, isomers, hydrates, prodrugs or polymorphs thereof may be included in such combinations.
The present invention also provides a process to manufacture the compositions according to the present invention.
The present invention provides a process of preparing a dry powder inhalation formulation which process comprises admixing of a pharmaceutically acceptable carrier or excipient with the actives and providing the formulation as a dry powder inhaler.
CLINICAL STUDIES:
Two randomized, single dose, crossover pharmacokinetic studies (with and without charcoal) were performed comparing Zanamivir (5 mg dose per inhalation X 2 inhalations) [Manufactured by Cipla Limited, Administered via Cipla Revolizer™ ] as test with Relenza (containing Zanamivir 5 mg per inhalation X 2 inhalations ) as reference in healthy subjects.

STUDY 1:
A randomised, single dose, open-label, two-way, crossover pharmacokinetic study in 6 healthy human adult, male subjects was carried out with a washout period of 7 days between each treatment period. On the dosing day subjects were administered single dose of 10 mg of Zanamivir (5 mg dose per inhalation X 2 inhalations). Pre-dose sample (baseline) was taken within one hour prior to dosing and serial blood sampling was done up to 24.00 hours post-dose. Analysis of serum samples for concentrations of Zanamivir was done using a validated (Liquid chromatography-mass spectrometry) LC-MS/ (Mass Spectrometry) MS method. Statistical comparison of the pharmacokinetic parameters of both the test and reference products was performed.
Both, the test and reference products were reasonably well tolerated after a single oral dose of test product or reference product of Zanamivir in healthy adult male human subjects under fasting conditions. No adverse events or serious adverse events reported during the conduct of the study.
STUDY 2:
A randomised, single dose, open-label, two-way, crossover pharmacokinetic study comparing Zanamivir (5 mg dose per inhalation X 2 inhalations) [Manufactured by Cipla Limited, Administered via Cipla Revolizer™] with Relenza (containing Zanamivir 5 mg per inhalation X 2 inhalations ) as 10 mg dose in 12 healthy adult male subjects under fasting conditions using charcoal blockade method. 80 ml (approximately 8 gm) activated charcoal suspension was given approximately 2 minutes prior to the first inhalation, followed by 80 ml activated charcoal suspension at 0.50, 1.00, 2.00 and 4.00 hours post dose. Pre-dose sample (baseline) was taken within one hour prior to dosing and serial blood sampling was done up to 24.00 hours post-dose. Analysis of serum samples for concentrations of Zanamivir was done using a validated (Liquid chromatography-mass spectrometry) LC-MS/ (Mass Spectrometry) MS method. Statistical comparison of the pharmacokinetic parameters of both the test and reference products was performed.

Both, the test and reference products were reasonably well tolerated after a single oral dose of test product or reference p mixture obtained in step (2) roduct of Zanamivir in healthy adult male human subjects under fasting conditions.
The following examples are for the purpose of illustration of the invention only and are not intended in any way to limit the scope of the present invention.
Example 1

Sr. No. Ingredients Qty/Unit
(mg/capsule)
1. Zanamivir 3.00
2. Coarse Lactose 15.40
3. Fine Lactose 6.50
Total 25.00
Process:
1) Zanamivir was sifted with fine lactose.
2) The mixture obtained in step (1) was co-sifted with coarse lactose.
3) The mixture obtained in step (2) was blended and filled into capsules.
Example 2

Sr. No. Ingredients Qty/Unit
(mg/capsule)
1. Zanamivir 4.00
2. Coarse Lactose 14.70
3. Fine Lactose 6.30
Total 25.00

Process:
1) Zanamivir was sifted with fine lactose.
2) The mixture obtained in step (1) was co-sifted with coarse lactose.
3) The mixture obtained in step (2) was blended and filled into capsules.
It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the spirit of the invention. Thus, it should be understood that although the present invention has been specifically disclosed by the preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and such modifications and variations are considered to be falling within the scope of the invention.
It is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "an excipient" includes a single excipient as well as two or more different excipients, and the like.