FIELD OF THE INVENTION

The present invention relates to a dry powder inhalation formulation and more particularly to dry powder inhalation formulation of the classes endothelin- receptor antagonists like Ambrisentan, Macitentan and Bosentan and angiotensin II receptor antagonists like Valsartan, Telmisartan, Losartan, Olmesartan, Irbesartan, Candesartan, Eprosartan and Azilsartan.

BACKGROUND OF THE INVENTION

Pulmonary hypertension (PAH) is a type of high blood pressure that affects the arteries of the lungs. The blood pressure in the pulmonary arterial circulation is much lower than the systemic blood pressure and does not exceed 30/15 mmHg even during exercise. Pulmonary hypertension is defined as a systolic blood pressure in the pulmonary arterial circulation above 30 mmHg. PAH is a disease having high mortality and is characterized by a progressive increase in pulmonary vascular resistance (PVR) and pulmonary artery pressure (PAP) leading to right ventricular failure and death. The incidence and prevalence of PAH are estimated at 2.4-7.6 cases/million/year and 15-26 cases/million/year, respectively, in large population studies with-2:l female male ratio.

Several drugs & drug formulations have been known as a treatment option for PAH. Some of the preferred classes are endothelin-receptor antagonists and angiotensin II receptor antagonists. Angiotensin II receptor antagonists bind to and inhibit the angiotensin II type 1 receptor (ATI) and thereby block the arteriolar contraction. Blockage of ATI receptors directly causes vasodilation and reduces blood pressure. One of the most commonly preferred drugs for treatment of PAH is Bosentan. Bosentan is an orally active dual Endothelin-Receptor Antagonist that acts on the endothelin-A (ETA) and endothelin-B (ETB) receptors. Bosentan has a distinct advantage of acting through both ETA as well as ETB receptors (A: B selectivity is 30:1), thereby contributing to dilatation of all three layers of pulmonary artery, i.e., intima, media, adventitia.

The patent application W02008009071A2 by Messadek Jallal provides a pharmaceutical composition that includes betaine and one or more endothelin receptor antagonist. The drug is administered as oral, parenteral, subcutaneous, inhaled, transdermal, slow release, controlled release, delayed release dosage form thus making it suitable for oral, parenteral, subcutaneous, transdermal, rectal and vaginal administrations. The amount of endothelin antagonist compound administered is in the range of 100mg-250mg.

The endothelin-receptor antagonists and angiotensin II receptor antagonists are administered orally or intravenously for the treatment of PAH. However, these formulations are delivered to the site of action (secondary and tertiary bronchial arteries) systemically resulting in miniscule quantity of drug being delivered to the actual site of action and hence the dosage is much higher than necessary. Moreover, small quantity of the drug is delivered at the actual site of, action with high probability of insufficient drug for treating the blockages in the terminal arteries and arterioles. Therefore, there is a need for targeted delivery of only the desired amount of the drug to the actual site of action and avoiding systemic delivery of undesirably large quantity of the drug. Thus, there is a need of a formulation that assists in delivery of endothelin-receptor antagonists and angiotensin II receptor antagonists having maximum therapeutic activity and minimum side effects.

Further there is a need to deliver the endothelin-receptor antagonists in the form of a dry powder inhaler formulation that will aid targeted delivery of the formulation in appropriate amount. There is a further need of a dry powder inhaler formulation that has a desired particle size such that the effective amount of the active agent is directly delivered to the lung membranes.

SUMMARY OF THE INVENTION The present invention relates to a dry powder formulation of the active pharmaceutical ingredient (API) selected from endothelin receptor antagonists or angiotensin II receptor antagonists in an amount ranging from 0.01% to 99.99% and optionally a suitable pharmaceutically acceptable excipient or an admixture of one or more excipients in an amount ranging from 99.99% to 0.01%.

The endothelin receptor antagonists are selected from one or more of Ambrisentan, Macitentan, Sitaxentan, Bosentan and their salts, solvates, adducts, cocrystals thereof. The angiotensin II receptor antagonists are selected from one or more of Valsartan, Telmisartan, Losartan, Olmesartan, Irbesartan, Candesartan, Eprosartan, Azilsartan and their salts, solvates, adducts, cocrystals thereof. The pharmaceutically acceptable excipients are selected from one or more of monosaccharides, disaccharides, oligo- or polysaccharides, polyalcohols, salts thereof like lactose (monohydrate and/or anhydrous), mannitol, magnesium stearate, L-leucine, glucose, arabinose, saccharose, maltose, dextran, sorbitol, xylitol, sodium chloride, calcium carbonate or mixtures thereof.

The particle size of the active pharmaceutical ingredient (API) is in the range of 0.5 to lOp. 90% particles of the API are not more than 5 pM, more preferably between 1 to 3.5 pM in size. The formulation is used for treatment of a disease that is responsive to the administration of the formulated drug, including administering to a host in need thereof. The formulation is used for treatment of pulmonary arterial hypertension.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood from the detailed description and the accompanying drawings/figures described herein below. These are only shown as illustrative of the means, therefore, not intended to limit the present invention.

FIGS.1 A- IB depict the particle size distribution of Bosentan Monohydrate; FIG. 2A-2B depict the device performance at different flow rates;

FIG. 3 depicts the in vitro drug release studies of Bosentan Monohydrate;

FIG. 4 depicts DSC of pure and jet milled Bosentan Monohydrate;

FIG. 5 depicts the XPRD analysis of Bosentan Monohydrate;

FIGS. 6A-6C depict SEM analysis of Bosentan Monohydrate, jet milled Bosentan Monohydrate and DPI blend;

FIG. 7 depicts the FT-IR analysis of Bosentan Monohydrate & Bosentan Monohydrate formulation;

FIG. 8A-8D depict FT-IR analysis for pure and spray dried Valsartan and Ambrisentan;

FIG. 9A-B depict XRPD analysis for pure and spray dried Valsartan;

FIG. 9C depicts XRPD analysis for pure and spray dried Ambrisentan;

FIG. 10 A-B depict SEM analysis for pure and spray dried Valsartan;

FIG. 10 C-D depict SEM analysis for pure and spray dried Ambrisentan;

FIG. 11 A-B depicts the in vitro drug release studies of Valsartan and Ambrisentan respectively.

DESCRIPTION OF THE INVENTION

The invention described herein is explained using specific exemplary details for better understanding. However, the invention disclosed can be worked on by a person skilled in the art without the use of these specific details.

References in the specification to "one embodiment" or "an embodiment" means that particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

References in the specification to “preferred embodiment” means that a particular feature, structure, characteristic, or function described in detail thereby omitting known constructions and functions for clear description of the present invention.

The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.

The present invention provides a dry powder inhalation (DPI) formulation of an endothelin receptor antagonists such as Ambrisentan, Macitentan and Bosentan and angiotensin II receptor antagonists such as Valsartan, Telmisartan, Losartan, Olmesartan, Irbesartan, Candesartan, Eprosartan and Azilsartan for the treatment of pulmonary hypertension.

An aspect of the present invention is to provide a formulation capable of local delivery of the active pharmaceutical ingredient (API) in the lungs, in significantly lower doses. The local drug delivery to all parts of lung membranes, pulmonary fluid and pulmonary arteries should be able to effectively cause vasodilation. This objective is achieved by using particle size of micron range 5p or less, more preferably 3p or less with an average particle size (d90) of 1.0 to 3.5p.

In a preferred embodiment of the present invention, the formulation includes i) the active pharmaceutical ingredient (API) in an amount ranging from 0.01% to 99.99% and ii) optionally a suitable pharmaceutically acceptable excipient or an admixture of one or more excipients in an amount ranging from 99.99% to 0.01%. In this embodiment, the active pharmaceutical ingredient is selected from endothelin receptor antagonists such as one or more of Ambrisentan, Macitentan, Sitaxentan, Bosentan and their salts, solvates, adducts, cocrystals thereof or angiotensin II receptor antagonists such as one or more of Valsartan, Telmisartan, Losartan, Olmesartan, Irbesartan, Candesartan, Eprosartan, Azilsartan and their salts, solvates, adducts, cocrystals thereof in an amount ranging from 0.01% to 99.99% The particle size of the API (d90) is in the range of 0.5 to lOp, more preferably 3p or less with an average particle size (d90) of 1.0 to 3.5p.

The pharmaceutically acceptable excipients are selected from one or more of monosaccharides, disaccharides, oligo- or polysaccharides, polyalcohols, salts thereof, like lactose (monohydrate and/or anhydrous), mannitol, magnesium stearate, L-leucine, glucose, arabinose, Saccharose, maltose, dextran, Sorbitol, Xylitol, Sodium chloride, calcium carbonate or mixtures thereof in an amount ranging from 99.99% to 0.01%.

In another embodiment, the API is present in an amount ranging from 10 mcg to 50 mg.

The formulation is prepared by a single or a combination of particle engineering techniques selected from Jet milling, Spray drying, Ultrasonication and Electro spinning.

Advantageously, Endothelin receptor antagonists have a distinct advantage of acting through both ETA as well as ETB receptors (A:B selectivity is 30:1), thereby contributing to dilatation of all three layers of pulmonary artery, i.e., intima, media, adventitia. ETA as well as ETB are present in abundance in small pulmonary arteries that indicates presence of these receptors in the vicinity of alveolar sacs. Angiotensin II receptor antagonists bind to and inhibit the angiotensin II type 1 receptor (ATI) and thereby block the arteriolar contraction. Blockage of ATI receptors directly causes vasodilation and reduces blood pressure. Therefore, dilatation of these pulmonary arteries and arterioles significantly reduce the arterial blood pressure and treat pulmonary arterial hypertension. Further local drug delivery, through a DPI formulation, to all parts of lung membranes, pulmonary fluid and pulmonary arteries would be able to effectively cause vasodilation. Therefore, local delivery of API in the lungs, in significantly lower doses, is expected to be significantly more efficacious than the oral route. Lower dose further contributes to reduced systemic side effects.

EXAMPLES

The examples illustrated below describe the evaluation methodology of the API, preparation, in vitro studies and characterization of the DPI blend.

Example 1.1 & 1.2- Particle engineering & Particle size analysis:

Bosentan Monohydrate (BM) was subjected to conventional (Spray Drying and Jet Milling) and some new (Electrospinning and Ultrasonication) techniques to produce desired particle size. Spray drying: 2% BM dispersions were prepared by dissolving BM in various solvents i.e. aqueous and organic and subjected to spray drying (LU-222, Advance spray dryer, Labultima, India). Aqueous (Distilled water), Alcoholic (Methanol) and Organic (DMSO) dispersions were spray dried to produce spray dried bosentan monohydrate (SDBM). The spray drying conditions are depicted in Table- 1 as below.

Table-1: Spray Drying Conditions Electrospinning: 2% BM dispersions were prepared by dissolving BM in methanol and subjecting to electrospinning (Physic equipment, India). The electrospinning conditions are depicted in Table-2 as below.

Table-2: Electrospinning Conditions

Ultrasonication: Two different concentrations of BM dispersions were prepared by dissolving BM in distilled water and were then subjected to magnetic stirring followed by ultrasonication (UCX 500, Sonic and Material Inc). The three different sonication cycles were run to achieve the desired particle size. The sonicated dispersion was subjected Particle Size Distribution (PSD) analysis. The ultrasonication conditions are depicted in Table-3 as below.

Table-3: Ultrasonication Conditions

Jet milling: BM was subjected to jet milling (Midas Air Jet Mill). The jet milled product was subjected to Particle Size Distribution analysis. The jet milling conditions are depicted in Table-4 as below.

Table-4: Jet milling Conditions

The mean particle size was determined by laser diffraction technique using Malvern 2000 SM (Malvern Instruments, Malvern, UK). The mean particle size was expressed in terms of d (0.9) i.e. size of the 90% of the particles. The data presented are mean values of three independent samples produced under identical production conditions. The particle size of the BM and Jet Milled API was checked by laser diffraction technique using Malvern 2000 SM (Malvern Instruments, Malvern, UK) with the help of wet and dry assembly.

The results are as shown in FIG. 1 and Table 6 as below. Table-5: Initial particle size ofBM (before jet milling)

Table-6: Particle size of BM (after jet milling)

Example 2.1: Preparation of DPI Blend Two formulations were prepared. The first formulation was prepared with

500 mcg drug and the second formulation with 750 mcg drug. Both formulations contained an optimized blend of coarse and fine lactose. An accurately weighed amount of each lactose i.e. coarse and fine; dried at 100°C for 1 hour, was passed separately through sieve no 60# mesh. Accurate amount of engineered bosentan was mixed with lactose mixture by means of geometric dilution.

An accurately weighed 10 mg from blend (5 samples from 5 different places) was taken. Content uniformity was determined across each blend by HPLC/UV at 225nm.

Example 2.2: In-vitro drug deposition using TSI

Hard gelatin capsule (Size 3) filled with 25 mg of powder equivalent to 0.45 mg of jet milled BM was dispersed through a low resistance DPI device into a TSI at flow rate of 30 L/min for 4 sec. Prior to each actuation, the stage I and II was loaded with 7 and 30 ml of methanol respectively. After actuation drug deposited in the capsule, inhaler, mouthpiece, induction port, and stage I and II was collected by rinsing methanol in a volumetric flask. Drug content was assessed with HPLC and detection was carried out at 225 nm. The recovered dose (RD), emitted dose (ED) and fine particle fraction (FPF) was calculated for all batches.

Batch no. 3 and 10 were found to give most satisfactory results. The results are as shown in Table 7 as below.

Table 7: In vitro drug deposition data for various batches

Example 2.3: Device performance of 500 mcg formulation using ACI

Three different commercially available DPI devices were screened for their performance. The device resistance was determined across two (60 and 90 1/min) different flow rates on Anderson Cascade Impactor (ACI). Drug content was assessed with HPLC/UV at 225 nm. The recovered dose (RD), emitted dose (ED) and fine particle fraction (FPF) was calculated for each device.

At flow rate of 601/min Device 2 provided better FPF as compared to other two devices. At flow rate of 901/min Device 3 provided better FPF as compared to other two devices. The results are as shown in FIG. 2 and Table 8 as below.

Table 8: Device performance at different flow rates

Example 2.4: In vitro release study In vitro release study was performed by using dialysis bags (Dialysis membrane 110, Hi Media, India) Briefly, dialysis bag was immersed in and washed twice with boiling water for 15 min followed by rinsing in phosphate buffered saline (PBS, pH 7.4) solution. Powder equivalent to ten doses of pure drug and formulated BM DPI (one dose eq. to 0.45mg) were dispersed in 2 ml PBS and this dispersion was loaded in the dialysis bag sealed at both the ends after vortexing for 5 s. The drug release was evaluated after immersing dialysis bag in 100 ml PBS (pH 7.4) with 10% methanol, placed in vertical diffusion cell maintained at room temperature as dissolution medium stirred at 50 rpm for 24 h. 2 ml of the release medium was withdrawn for drug release at different time intervals (0-12 h) and replaced with 2 ml of fresh medium. The amount of drug released was measured by HPLC (HPLC, PU 2080, JASCO, Japan) having a UV-VIS detector and detection wavelength was set at 225nm. Using a standard calibration curve the absorbance was converted into percentage release. To examine the drug release kinetics and mechanism, the data were subjected to the different kinetic models.

In vitro drug release studies on the 500 mcg formulation showed approximately 75 and 50% drug release at the end of 12 h from formulation and pure drug respectively. The results are as shown in FIG. 3 and Table 9 as below.

Table 9: In vitro drug release

Example 3.1: Differential Scanning Calorimeter (DSC):

DSC was performed by using Mettler DSC821, (Mettler Toledo, Switzerland). Accurately weighed samples (5-10 mg) were hermetically sealed in aluminum pans and heat cycle was applied from 50 to 300°C at a constant rate 10°C/min. An inert atmosphere was maintained by purging with nitrogen gas at a flow rate of 100 ml/min.

Results: Jet Milling doesn't induce any amorphization and/or chemical decomposition to API. The results are as shown in FIG. 4.

Example 3.2: Powder X-ray Diffraction (XRPD):

X-ray powder diffraction (PW1729, Philips, Netherland) spectra were collected from scans 10 to 50° at 29. The samples were irradiated with mono- chromatized CuK a radiation (1.542 A) before the testing. The voltage and current used were 30 kV and 30 mA, respectively. The range and the chart speed were 1 x 104 CPS and 10 mm/29°, respectively.

The crystalline nature of BM and Jet Milled API was confirmed from sharp XRD peaks (19-25 -26). The optimized batch of DPI blend also shows the peaks between 19-25 -26. The results are as shown in FIG. 5.

Example 3.3: Scanning Electron Microscopy (SEM):

SEM (Energy dispersive spectrometer, JE6L JSM- 6360A) was performed to obtain surface morphology and homogeneity of particles of both pure drug and jet milled drug and optimized DPI blend. To improve conductivity prior to examination, samples were sputtered with gold coater at room temperature.

Results: Jet Milling produced small, irregularly shaped flat particles. Fine lactose fill pores present in coarse lactose. Drug particles ride over lactose blend. The results are as shown in FIG. 6.

Example 3.4: Diffuse reflectance infrared fourier transform spectroscopy:

FTIR (JASCO, FTIR-4100, Japan) having a diffuse reflectance accessory was used to perform infrared analysis. Approximately 1-2 mg of powdered sample was mixed with dry potassium bromide and samples were examined in transmission mode over wave number range of 4000 to 400 cm-1. Jasco spectra manager Ver. 2 (Japan) was used for data acquisition and analysis.

Results: The characteristic peaks at 1375-1300 cm-1 (sulfate group; O=S=O) and 3650-3600 cm-1 (Hydroxyl group with Nitrogen; OH&N) were observed in BM, jet milled BM and DPI blend. The results are as shown in FIG. 7.

Example 3.5: Flow properties of DPI

The powder flow properties were characterized using the angle of repose, Carr's compressibility index and the Hausner ratio, calculated from the tapped and bulk densities. Bulk density was calculated by filling the powder in a 10 ml measuring cylinder, and followed by 500 taps using tap density tester (Electrolab, ETD-1020, USP, Mumbai, India).

Results: Lower angle of repose, Carr's compressibility index and Hausner ratio values indicate satisfactory flow properties. The results are as shown in Table 10.

Table 10: Flow properties of optimised DPI blend

The results of all the studies indicate that the formulation of the current invention is suitable to be administrated as a DPI formulation.

Example 4.1: Particle Engineering: Spray drying of Valsartan (VA) and Ambrisentan (AM)

Each pure drug was first dissolved in ethanol. The prepared solution was subjected to spray drying (LU-222, Advanced Spray Dryer, Labultima, India) leading the drug solution to be atomized to fine droplets that evaporate in hot conditions to form dry particles. The parameters for spray drying are depicted in Table 11 as below.

Table 11: Spray drying parameters for Valsartan and Ambrisentan

Example 4.2: Particle Size Analysis for Spray Dried Valsartan (VA) and Ambrisentan (AM)

The mean particle size of pure drugs and spray dried drugs was determined by laser diffraction technique using Malvern 2000 SM (Malvern Instruments, Malvern, UK). The mean particle size was expressed in terms of d (0.95) i.e., size of the 95 % of the particles. The results are as shown in Table 2 below. Table 12: Tabulation of Particles size data for pure and spray dried Valsartan and Ambrisentan

Example 5.1: Preparation of Dry Powder Inhalation (DPI) Formulations of Valsartan (VA) and Ambrisentan (AM).

Spray dried VA was formulated with Lactose monohydrate (Meggle GmbH & Co. KG) and without excipient as depicted in Table 3.

Table 13: Formulations of Valsartan and Ambrisentan

AM (spray dried) was accurately weighed drug and transferred into a stainless steel container. Glass beads were added in the ratio of 1: 4 (spray dried drug: glass beads). The container was closed and shaken continuously for 30 mins, in upward and downward directions alternately. The above powders were filled manually in hydroxyl propyl methyl cellulose capsules (HPMC size-3) for further evaluation.

Example 5.2: Analytical Method for assay of Valsartan (VA) and Ambrisentan (AM) in respective formulations 10 mg drug was dissolved in 10 ml ethanol (1000 ppm solution). This solution was suitably diluted to obtain a 10 ppm solution and was scanned on an ultra violet-visible spectrophotometer (JASCO, V-630, Japan) between 200- 400 nm for determining Xmax for each drug. It was found that VA exhibited an intense maximum absorption at 250 nm while AM at 265 nm. Further, dilutions ranging from 0.1 to 50 ppm of standard VA/ AM were prepared using ethanol and the absorbances were recorded at respective /.max values. A calibration curve of the absorbance was plotted against concentration. The limit of detection, limit of quantitation and regression coefficient were calculated for each drug separately. The values are given below in Table 14.

Table 14: Analytical method validation data for Valsartan and Ambrisentan

Example 6: Characterization of Spray Dried Valsartan and Ambrisentan

Example 6.1: Fourier Transform Infra- Red spectroscopy (FTIR)

Pure and spray dried VA and AM were analysed by infrared spectroscopy (IR) to assess structural changes if any due to spray drying. Potassium bromide (KBr) was activated in a hot air oven for 15-20 min. Drug sample was mixed with KBr in the ratio of 1:9 and the IR spectrum was recorded (JASCO, FTIR-4100, Japan) in the range of 4000 to 400 cm ¹ .

Results: All peaks corresponding to major functional groups in both drugs were also observed in the IR spectrum of the respective spray dried drugs, thus indicating no structural changes in the drugs due to spray drying. The results are as shown in Figures 8A to 8D and Table 15.

Table 15: FT-IR analysis for pure and spray dried Valsartan and Ambrisentan

Example 6.2: X-ray powder diffraction (XRPD) XRPD (PW 1729, Philips, Netherland) spectra were collected from scans 10 to 50° at 29 for both pure drugs and respective spray dried VA and AM as shown in FIG. 9. The samples were irradiated with mono-chromatized CuK a radiation (1.542 A) before the testing. The voltage and current used were 30 kV and 30 mA, respectively. The range and the chart speed were 1 ^ 104 CPS and 10 mm/29°, respectively.

Results: Crystallinity of VA was not affected due to spray drying while in case of AM crystalline component was found to have increased. Example 6.3: Scanning electron microscope (SEM)

The SEM study was performed to analyze the morphological characters of the prepared samples (FEI Nova NanoSEM 450). Before the analysis of the samples, they were completely dried. The samples were then sputter coated with gold in order to improve conductivity prior to examination. The images were viewed at 5, 10, 50, 100 pm to determine the morphological shape of each pure drug and respective spray dried VA and AM.

Results: SEM analysis showed that in case of VA irregular sized and shaped particles before spray drying were converted to regular spherical particles after spray drying (FIG. 10A and B).

In case of AM, the particle shape did not change much (Figure 10C and D).

Example 7: Performance Evaluation of VA and AM Dry Powder Inhalation Formulations

Example 7.1: In-vitro drug release study

In vitro release study was performed using dialysis bags (Dialysis membrane 110, Hi Media, India) Briefly, the dialysis bag was immersed in and washed twice with boiling water for 15 minutes and soaked overnight in release medium followed by rinsing in phosphate buffered saline (PBS, pH 7.4) solution. For VA, 15 mg pure drug, 15 mg spray dried drug and powder equivalent to 15 mg VA in formulated drug was used. For AM 10 mg pure drug and 10 mg spray dried drug was used. The samples were dispersed in 2 mF PBS after vortexing for 5 seconds and this dispersion was loaded in the dialysis bag sealed at both the ends. The drug release was evaluated after immersing dialysis bag in 900 mL PBS (pH 7.4) maintained at room temperature as dissolution medium stirred at 50 rpm for 24 hr (Dissolution Test Apparatus USP type II Electrolab, India). 5 mL of the release medium was withdrawn for drug release at different time intervals (0-12 h) and replaced with 5 mL of fresh medium. The amount of drug released was measured on UV Spectrophotometer at respective drug wavelengths. Using a standard calibration curve the absorbance was converted into percentage release. To examine the drug release kinetics and mechanism, the data was subjected to different kinetic models as shown in FIG. 11, Tables 16 and 17. Table 16: Kinetic model fiting for prediction of in vitro drug release for Valsartan

Table 17: Kinetic model fiting for prediction of in vitro drug release for Ambrisentan

Results: In case of VA, drug dissolution occurs by diffusion followed by erosion. Thus, it is predicted that complete drug disposition from lungs takes place. In case of AM after spray drying, diffusion occurs faster with the initial concentration. At later stages the drug dissolution continues with diffusion and erosion. Thus, it is predicted that complete drug disposition from the product takes place.

Example 7.2: Emitted Dose Calculation using Glass Impinger (GI) HPMC capsules were filled with formulations No. 2 and 3 (prepared as described in Table 13) were dispersed through a low resistance DPI device into a GI at a flow rate of 60 L/min. Prior to each actuation, the stage I and II was loaded with 7 and 30 ml of ethanol respectively. After each actuation drug deposited in the capsule, inhaler, mouthpiece, induction port, and stage I and II was collected by rinsing with ethanol in a volumetric flask. Drug content was assessed on UV spectrophotometer and detection was carried out at respective drug wavelengths. The results are as shown in Table 18 as below.

Table 18: Emitted Dose for Valsartan and Ambrisentan

Results: Satisfactory deposition in stage II of GI was observed for both Valsartan and Ambrisentan.

Example 7.3: Aerodynamic Particle Size Analysis using Next Generation Impactor (NGI)

The apparatus (Next Generation Impactor- Copley Scientific) was washed with water and then rinsed with methanol. All stages and plates were wiped with tissue paper. The apparatus was completely dried with the help of drier and it was ensured that all solvent is removed from the apparatus. The system was made airtight by checking the tube joints. The flow was adjusted to 100 ± 5 litre / min for 2.4 seconds. The device was fitted to induction port through mouthpiece.

The mouthpiece was rinsed with diluent, sonicated for about 5 minutes, (sonicator bath temperature between 20-25 °C) and diluted to 10 ml with diluent. The solution was filtered through 0.45 pm Nylon syringe filter by discarding initial 5 ml of the filtrate. The induction port was removed, washed with diluent and shaken for about 5 minutes so that drug gets extracted in diluent, sonicated for about 5 minutes, (sonicator bath temperature between 20-25 °C) and finally diluted to 100 ml with diluent. The solution was filtered through 0.45 pm Nylon syringe filter by discarding initial 5 ml of the filtrate.

The pre-separator was removed washed with diluent and shaken for about 5 min so that drug gets extracted in diluent, sonicated for about 5 min. (sonicator bath temperature between 20-25 °C) and finally diluted to 100 ml with diluent. The solution was filtered through 0.45 pm nylon syringe filter by discarding initial 5 ml of the filtrate.

Stage- 1 to Stage-7 and Micro Orifice Collector (MOC):

All stages were removed individually and washed with diluent, sonicated about 5 min. (sonicator bath temperature between 20-25°C) and finally diluted to 10 ml with diluent individually. The solutions were filtered through 0.45 pm nylon syringe filters by discarding initial 5 ml of the filtrate.

The Fine Particle Fraction (FPF), mass median aerodynamic diameter (MMAD) and geometric size distribution (GSD) was calculated using Copley Inhaler Testing Data Analysis Software (CITDAS) and data for both drugs is compiled in Table 19.

Table 19: Aerodynamic Particle Size Analysis for Valsartan and Amrisentan

Results: the FPF of both drugs was found in line with GI drug deposition.

The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others, skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated.

It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention.