Chapter 7 FORMULATION AND CHARACTERIZATION OF PULSINCAP

Transcription

1 161 Chapter 7 FORMULATION AND CHARACTERIZATION OF PULSINCAP

2 162 Chapter 7 FORMULATION AND CHARACTERIZATION OF PULSINCAP S.No. Name of the Sub-Title Page No Optimization of formulations of Pulsincap Factorial Designs Evaluation of variables Formulation of Pulsincap Preparation of formaldehyde treated capsule Evaluation of formaldehyde treated empty 169 capsules Solubility studies of the treated capsules Qualitative test for the free formaldehyde Preparation of hydrogel plug Development of pulsincap formulation Preparation of bosentan pellets Evaluation of pulsincap Disintegration test Uniformity of weight Estimation of drug content Determination of swelling index In vitro study Treatment of dissolution data with kinetic 178 models 7.5. Results and discussion Conclusion 215

3 FORMULATION AND CHARACTERIZATION OF PULSINCAP Based up on the satisfied results obtained from the preformulation studies, the drug Bosentan and polymers such as HPMC K15, Carbapol, Guar gum and Karaya gum were proved as promising candidates for the development of controlled drug delivery system. 7.1 Optimization of formulations of Pulsincaps A 2 3 factorial design was most commonly used to evaluate main effects and interaction effects of the formulation ingredients on the in vitro of drug from the formulations and to arrive at an optimum formula with desired drug characteristics Factorial Designs 2 3 Hydrogel plug in pulsincap formulation, when it is come in contact with body fluid will swell due to presence of swellable matrix through which the drug d for a prolonged period of. A two level three factor full factorial design was employed for optimization of the formulations in combination of drug, polymer and diluent. The 2 3 factorial design, construction of response surface and polynomial equations were done using trial version of Design Expert software v8..7.1, Stat-Ease Inc., Minneapolis, MN, United States of America. The linear interactive model is shown in the following equation. Y= b+b1x1+b2x2+b3x3+b4x1x2+b5x1x3+b6x2x3

4 164 Where Y is the dependent variable, b is the arithmetic mean response and b1, b2 and b3 are estimated regression coefficient for the factor X1. The main effects (X1, X2 and X3) represent the average result of changing one factor from its low to high values. The interaction term (X1X2 X3) shows how the response values change when three factors are simultaneously changed One-way ANOVA was applied to estimate the significance of the model (p<.5) and response parameters. The goal of present study is to attain an optimum and efficacious formulation of Pulsincaps of Bosentan that would have the following behaviours, Excellent swelling index Good physical and chemical stability An optimized model was identified for response and also to validated such model developed statistically be comparing theoretically obtained values with the experimental values. The runs in coded values are given in Table 7.2. A 2 3 factorial design was applied and aimed to have constrains in the factorial design experiment so as to get the best desirable characteristics out of the Pulsincaps, where three variables were fixed such as X1 is the amount of matrix forming polymer, X2 is the Percentage of swelling Index and X3 is the target to % of drug (T). The levels of polymer, swelling index and to % of drug are set to low and high values are shown in the table 7.1.

5 165 Table 7.1: Levels of Matrix forming polymer, Swelling Index and Level Time to % of drug Amount of Polymer in mg (X1) Hardness kg/cm 3 (X2) Swelling Index in % (X3) Low (-1) 1 3 High (+1) Based on the selected responses of three variables (X1, X2 and X2), the ratio of matrix forming polymers and (X3) Swelling Index (X2) were optimized and total 16 formulations were set to prepared. The compositions of drug, polymer and other additives of all formulations were presented in the Table 7.3. Table 7.2: Factorial design of the formulation with coded value Run No. Amount of Polymer in mg (X1) and constraints Variable Hardness kg/cm 3 (X2) Swelling Index in % (X3) Response Drug at 6th Hr in %

6 Evaluation of variables The optimized formulations were identified based on constrains used in the experiment. The optimized formulations were compressed into Pulsincaps according to the method given in 7.2 and evaluated for to get T% in vitro drug, results were presented in Table 7.2. The optimized formulations were further studied for mechanism of drug by fitting the in vitro drug data into different kinetic models. Design-Expert Software Drug at 6th Hr Error estimates A: Amount of Polymer B: Hardness C: Swelling Index Positive Effects Negative Effects H a lf - N o r m a l % P r o b a b ilit y AC C A ABC B Half-Normal Plot AB BC Standardized Effect Figure 7.1: Half-Normal plot showing the standardized effect and Half-Normal % probability

7 167 Design-Expert Software Factor Coding: Actual Drug at 6th Hr Drug at 6th Hr X1 = A: Amount of Polymer X2 = B: Hardness Actual Factor C: Swelling Index = 75. B : H a r d n e s s A: Amount of Polymer Design-Expert Software Factor Coding: Actual Drug at 6th Hr Drug at 6th Hr X1 = A: Amount of Polymer X2 = C: Swelling Index Actual Factor B: Hardness = 3. C : S w e llin g I n d e x A: Amount of Polymer Design-Expert Software Factor Coding: Actual Drug at 6th Hr Drug at 6th Hr 48.5 X1 = B: Hardness X2 = C: Swelling Index Actual Factor A: Amount of Polymer = 25. C : S w e llin g I n d e x B: Hardness Figure 7.2: Contour plot showing the effect of polymer concentration on drug at 6th Hr Design-Expert Software Factor Coding: Actual Drug at 6th Hr X1 = A: Amount of Polymer X2 = B: Hardness X3 = C: Swelling Index Cube Drug at 6th Hr B+: 4. B : H a r d n e s s C+: 1. C: Swelling Index 2 2 B-: C-:. A-: 1. A+: 4. A: Amount of Polymer Figure 7.3: Cube plot showing the effect of polymer concentration on drug at 6th Hr

8 168 Design-Expert Software Factor Coding: Actual Drug at 6th Hr X1 = A: Amount of Polymer X2 = B: Hardness Actual Factor C: Swelling Index = 75. D r u g r e le a s e a t 6 t h H r B: Hardness A: Amount of Polymer 4. Design-Expert Software Factor Coding: Actual Drug at 6th Hr X1 = A: Amount of Polymer X2 = C: Swelling Index Actual Factor B: Hardness = 3. D r u g r e le a s e a t 6 t h H r C: Swelling Index A: Amount of Polymer 4. Design-Expert Software Factor Coding: Actual Drug at 6th Hr X1 = B: Hardness X2 = C: Swelling Index Actual Factor A: Amount of Polymer = 25. D r u g r e le a s e a t 6 t h H r C: Swelling Index B: Hardness Design-Expert Software Factor Coding: Actual Drug at 6th Hr X1 = A: Amount of Polymer X2 = B: Hardness Actual Factor C: Swelling Index = D r u g r e le a s e a t 6 t h H r B: Hardness A: Amount of Polymer 4. Figure 7.4: 3D surface plot showing the effect of polymer concentration on drug at 6th Hr drug

9 Formulation of pulsincap Preparation of formaldehyde treated capsules: Empty hard gelatin capsules were used to develop the pulsincap formulations. Bodies of hard gelatin capsules were treated with formaldehyde for insolubility, and the caps of the gelatin capsules were used as such. Bodies of hard gelatin capsules (size ) were placed on a wire mesh. Formaldehyde (15%) was taken into a Petri dish and kept in a desiccator and potassium permanganate was added to it until vapors were produced. The wire mesh containing the bodies was then exposed to formaldehyde vapors. The reaction was carried out for 12hrs after which the bodies were removed and dried at C for 3 min to ensure completion of reaction between gelatin and formaldehyde vapors. The bodies were then dried at room temperature to ensure removal of residual formaldehyde Evaluation of formaldehyde treated empty capsules Various physical and chemical tests were carried out simultaneously for formaldehyde treated and untreated capsules Solubility studies of the treated capsules The solubility tests were carried out for both normal capsules and formaldehyde treated capsules for 24hrs. Ten capsules were randomly selected. These capsules were then subjected to solubility studies at room temperatures in buffers of ph 1.2 HCl and ph 7.4, 6.8 phosphate bffers. 1ml of buffer solution was taken in a beaker. A single capsule was placed in the buffer solution and stirred for 24 hrs.

10 17 The at which the capsule dissolves or forms soft fluffy mass was noted Qualitative test for the free formaldehyde Formaldehyde treated bodies of the capsules were cut into small pieces and taken into a beaker containing distilled water. This was stirred for 1hr. with a magnetic stirrer, to solubilize the free formaldehyde. The solution was then filtered into a ml volumetric flask, washed with distilled water and the volume made up to ml with the washings. To 1ml of sample solution, 9 ml of water was added. 1ml of the resulting solution was taken into a test tube, and mixed with 4ml of water and 5ml of acetone. The test was warmed in a water bath at 4 C and allowed to stand for 4 min. The solution was not more intensely colored then a reference solution prepared at the same and in the same manner using 1ml of standard solution in place of the sample solution. The comparison should be made examining the tubes down their vertical axis Preparation of hydrogel plug Four types of plugs were prepared by compressing polymer: lactose (1:1) ratio using 7 mm punches and dies on rotary tablet punching machine. The hydrogel plugs were evaluated for thickness, hardness, and lag parameters 191,192. The composition of different types of hydrogel plugs were given in the table 7.3.

11 171 Figure 7.5: Photographs showing formulation of Pulsincaps and Coating of pellets using FBD, done by myself at industry

12 172 Table 7.3: Composition of hydrogel plug Formulation HPMC Carbapol Guar Karaya Lactose Code K15 gum gum monohydrate PC PC PC PC PC PC PC PC PC PC PC PC PC PC PC PC *All ingredients were taken in mg, 1% w/w of Aerosil was used as a glident for all hydrogel plug Development of pulsincap formulation The developed system contained hydrogel plug prepared with swellable polymer such as Hydroxy propyl methylcellulose (HPMC K15m), Guar gum, Karaya gum, and Carbapol together with pellets coated with drug and polymers separately with concentrations of 1, 2, 3 and 4mg. Bodies of gelatin capsules of size hardened with formaldehyde for 12hrs were taken for preparing the pulsincap body mg equivalent weights of drug containing pellets were filled into the hardened capsule body. The remaining volume of the capsule body was filled with swellable polymer hydrogel plug and erodible plug. Then the soluble cap was locked into the body to form the controlled

13 173 pulsincap device 193,194. The prepared pulsincap devices were used for further evaluation studies Preparation of bosentan pellets a) Preparation of core pellets. The composition of the pellets is given in table. Non-pariel seeds (sugar pellet) (#22#24). Due to high solubility, the sugar pellets immediately get dissolved in aqueous media. In order to retard the dissolution rate of non-pariel seeds initially coated with 2 %( w/w) HPMC E5 as a seal coat followed by coated with slurry of drug solutions. b) Coating procedure The entire seal coating and drug layering processes were done by fluid bed process technology with following specifications. Inlet temperature Product temperature Exhaust temperature Atomization air pressure Peristaltic (spray pump) speed Fluidization air flow : 38-4 C : C : 3-32 C : 1-2 bars : 6-8rpm : -6cfm Slurry of bosentan with 6% croscarmellose sodium, 1% povidone K-3 (w/w) and.1% tween 8 were dissolved in 1ml of acetone. The seal coated sugar pellets (Non-pariel seeds) (#22#24) were preheated to about 35 C with gentle movement in FBD, and then sprayed the prepared slurry on to coating bed and % weight was build up to 3% w/w on sugar pellets were allowed to suspended for about 1min until

14 174 uniform drug coating occurs. Spray rate, inlet air temperature were adjusted in such a way that the core bed reaches a temperature of about 35 C. After sufficient amount of drug slurry was coated, the pellets were dried at about 45 C to have the moisture content of 2%. The dried pellets were sized using the sifter to remove agglomerates, broken pellets and fine powder 195. c) Evaluations of pellets Surface morphology of pellets was studies using LEICA S44i scanning electron microscope after coating them with gold vapors. Morphological analysis was carried out at different Magnification. The Carr s index and angle of repose of the pellets were also determined. Results for all these parameters were within the standard limit and satifactory 196. Figure 7.6: Surface morphology of pellets by SEM in various magnification

15 Evaluation of pulsincap Disintegration test: 1 capsules with treated bodies and untreated caps were randomly selected. These capsules were then subjected to disintegration studies at room temperatures in buffers of ph 7.4 and 6.8. A single capsule was placed in the buffer solution and stirred for 24hrs. The taken for the Capsule to disintegrate was noted Uniformity of weight 2 pulsincaps were randomly selected from each batch, weighed together and individually. The mean and standard deviation were studied Estimation of drug content 1 pulsincaps were randomly selected, and the contents were removed and powdered. From this sample 1mg equivalent amount of drug containing powder was accurately weighed and transferred into a 1ml volumetric flask. 1ml of methanol was added to dissolve the content. The solution is made up to the volume with ph 7.4 phosphate buffer. The resulted solutions was filtered through.45µm filter paper and suitably diluted, and the drug content was estimated spectrophotometrically by measuring the absorbance at 272nm Determination of Swelling Index Determination of swelling index of hydrogel plug was done by adopting the procedure from the previous chapter Page no. 18. The swelling indexes of hydrogel plugs are given in Table 7.4. and the plot of swelling index against in hrs depicted as Figure 7.7.

16 176 Table 7.4: Swelling index of hydrogel plug for Pulsincaps Code % of swelling with in hrs Mean ± SD PC ± ± ± ± ± ±1.33 PC ± ± ± ± ± ±.53 PC3 42.3± ± ± ± ± ±1.64 PC ± ± ± ± ± ±.92 PC ± ± ± ± ± ±.64 PC ± ± ± ± ± ±.53 PC7 34.4± ± ± ± ± ±.68 PC8 36.8± ± ± ± ± ±.73 PC ± ± ± ± ± ±.84 PC ± ± ± ± ± ±.64 PC ± ± ± ± ± ±.53 PC ± ± ± ± ± ±.47 PC ± ± ± ± ± ±1.67 PC ± ± ± ± ± ±.54 PC ± ± ± ± ± ±.53 PC ± ± ± ± ± ±.67 Each value represents the mean ± standard deviation (n=3)

17 Swelling Index in % s PC1 PC2 PC3 PC4 PC5 PC6 PC7 PC8 PC9 PC1 PC11 PC12 PC13 PC14 PC15 PC16 Figure 7.7: Swelling index of all formulation 7.4. In vitro study For in vitro profile, dissolution studies were performed for 12hrs for designed pulsincap dosage form according to USP dissolution apparatus 1(basket type) method. Phosphate buffer ph 7.4 was used as dissolution media. The medium was rotated at rpm. Samples were withdrawn at specific intervals and equal volume of media was replaced immediately. Withdrawn samples were then

18 178 filtered, suitability diluted and the amount of drug d was determined by UV spectrophotometer at 272nm Teatment of dissolution data with kinetic models The drug data were treated with various kinetic models such as cumulative percentage drug, Higuchi's, Peppa's and first order drug. The method was adopted from previous chapter 6.5. Page no The results of kinetic treatment applied to drug profile of best formulation are given in Table Graphs are shown from In vitro drug, Higuchi and Peppa s data for all formulations are given in Table from 7.5 to 7.2 and graphs are shown from Figure 7.8 to 7.71.

19 Time in Hrs 179 Table 7.5: In vitro drug and kinetic data for PC1 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.8: Cumulative percentage drug plot of PC1

20 Square root of Figure 7.9: Higuchi's plot of PC Log Figure 7.1: Peppa's plot of PC Cumulative Log Remaining Figure 7.11: First order plot of PC1

21 Time in Hrs 181 Table 7.6: In vitro drug and kinetic data for PC2 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.12: Cumulative percentage drug plot of PC2

22 Square root of Figure 7.13: Higuchi's plot of PC Log Figure 7.14: Peppa's plot of PC Cumulative Log Remaining Figure 7.15: First order plot of PC2

23 Time in Hrs 183 Table 7.7: In vitro drug and kinetic data for PC3 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.16: Cumulative percentage drug plot of PC3

24 Square root of Figure 7.17: Higuchi's plot of PC Log Figure 7.18: Peppa's plot of PC Cumulative Log Remaining Figure 7.19: First order plot of PC3

25 Time in Hrs 185 Table 7.8: In vitro drug and kinetic data for PC4 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.2: Cumulative percentage drug plot of PC4

26 Square root of Figure 7.21: Higuchi's plot of PC Log Figure 7.22: Peppa's plot of PC Cumulative Log Remaining Figure 7.23: First order plot of PC4

27 Time in Hrs 187 Table 7.9: In vitro drug and kinetic data for PC5 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.24: Cumulative percentage drug plot of PC5

28 Square root of Figure 7.25: Higuchi's plot of PC Log Figure 7.26: Peppa's plot of PC Cumulative Log Remaining Figure 7.27: First order plot of PC5

29 Time in Hrs 189 Table 7.1: In vitro drug and kinetic data for PC6 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.28: Cumulative percentage drug plot of PC6

30 Square root of Figure 7.29: Higuchi's plot of PC Log Figure 7.3: Peppa's plot of PC Cumulative Log Remaining Figure 7.31: First order plot of PC6

31 Time in Hrs 191 Table 7.11: In vitro drug and kinetic data for PC7 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.32: Cumulative percentage drug plot of PC7

32 Square root of 2.1 Figure 7.33: Higuchi's plot of PC Log Figure 7.34: Peppa's plot of PC Cumulative Log Remaining Figure 7.35: First order plot of PC7

33 Time in Hrs 193 Table 7.12: In vitro drug and kinetic data for PC8 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.36: Cumulative percentage drug plot of PC8

34 Square root of Figure 7.37: Higuchi's plot of PC Log Figure 7.38: Peppa's plot of PC Cumulative Log Remaining Figure 7.39: First order plot of PC8

35 Time in Hrs 195 Table 7.13: In vitro drug and kinetic data for PC9 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.4: Cumulative percentage drug plot of PC9

36 Square root of Figure 7.41: Higuchi's plot of PC Log Figure 7.42: Peppa's plot of PC Cumulative Log Remaining Figure 7.43: First order plot of PC9

37 Time in Hrs 197 Table 7.14: In vitro drug and kinetic data for PC1 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.44: Cumulative percentage drug plot of PC1

38 Square root of Figure 7.45: Higuchi's plot of PC Log Figure 7.46: Peppa's plot of PC Cumulative Log Remaining Figure 7.47: First order plot of PC1

39 Time in Hrs 199 Table 7.15: In vitro drug and kinetic data for PC11 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.48: Cumulative percentage drug plot of PC11

40 Square root of Figure 7.49: Higuchi's plot of PC Log Figure 7.: Peppa's plot of PC Cumulative Log Remaining Figure 7.51: First order plot of PC11

41 Time in Hrs 21 Table 7.16: In vitro drug and kinetic data for PC12 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.52: Cumulative percentage drug plot of PC12

42 Square root of 2.1 Figure 7.53: Higuchi's plot of PC Log Figure 7.54: Peppa's plot of PC Cumulative Log Remaining Figure 7.55: First order plot of PC12

43 Time in Hrs 23 Table 7.17: In vitro drug and kinetic data for PC13 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.56: Cumulative percentage drug plot of PC13

44 Square root of Figure 7.57: Higuchi's plot of PC Log Figure 7.58: Peppa's plot of PC Cumulative Log Remaining Figure 7.59: First order plot of PC13

45 Time in Hrs 25 Table 7.18: In vitro drug and kinetic data for PC14 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.6: Cumulative percentage drug plot of PC14

46 Square root of 2.1 Figure 7.61: Higuchi's plot of PC Log Figure 7.62: Peppa's plot of PC Cumulative Log Remaining Figure 7.63: First order plot of PC14

47 Time in Hrs 27 Table 7.19: In vitro drug and kinetic data for PC15 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.64: Cumulative percentage drug plot of PC15

48 Square root of 2.1 Figure 7.65: Higuchi's plot of PC Log Figure 7.66: Peppa's plot of PC Cumulative Log Remaining Figure 7.67: First order plot of PC15

49 Time in Hrs 29 Table 7.2: In vitro drug and kinetic data for PC16 Higuchi's Peppa's First Order Sq. Cumulative Cumulative Log Time root Log cumulative in of % Hrs Log % drug remaining Figure 7.68: Cumulative percentage drug plot of PC16

50 Square root of Figure 7.69: Higuchi's plot of PC Log Figure 7.7: Peppa's plot of PC Cumulative Log Remaining Figure 7.71: First order plot of PC16

51 PC1 PC2 PC3 PC4 PC5 PC6 PC7 PC8 PC9 PC1 PC11 PC12 PC13 PC14 PC15 PC16 Figure 7.72: Comparison of drug pattern of all Pulsincaps of Bosentan

52 Stability study The method adopted from the previous chapter 6.6 Page no. 1 and remaining parameters were same as described in in vitro drug study. The dissolution profiles were analyzed with the aid of dissolution similarity factor f2 and point analysis. The drug profiles were not affected by exposing to different temperature with specified humidity conditions. The stability data were analyzed using software Stab 176. The observed and calculated values are given in Table 7.2. The residuals obtained from the calculated values are shown in Figure The predicted shelf life for PC8 is shown in Figure The data of versus cumulative percentage drug profile are given in Table 7.21 and pattern were shown in Figure Table 7.21: Comparison of observed with calculated assay of best formulations subjected to stability study PC16 Time in months Observed Assay (%) Mean ± SD Calculated Assay (%) Mean ± SD ± ± ± ± ± ± ± ± ± ± ± ± 1.32 Each value represents the mean ± standard deviation (n=3)

53 213 Figure 7.73: Normal Q-Q plot of residuals obtained from calculated values of PC8 batches subjected for stability study Figure 7.74: Graph showing predicted shelf life of PC8

54 214 Table 7.22: Comparison of dissolution data of best formulations Time in hrs subjected to stability study with standard Standard Cumulative % drug of PC8 After 1 After 3 After 6 After 9 month months months months After 12 months Standard After 1 month After 3 months After 6 months After 9 months After 12 months Figure 7.75: Drug pattern of PC8 during stability study for up to 12 months

55 Results and discussion Evaluation of granules Evaluation parameters like bulk density, tap density, compressibility index, Hausner s ratio, angle of repose were evaluated for all batches of Pulsincaps, the results were presented in Table 6.6. The granulation process altered bulk density values, and hence the Carr s index got reduced to less than 2%. The granulation process also improved the flow property. The flow properties and derived properties evaluated for all 16 formulations were proven to be within limits showing good flow properties Physicochemical evaluation of Pulsincap a) Evaluations of pellets Surface morphology of pellets was studies using LEICA S44i scanning electron microscope after coating them with gold vapors. Morphological analysis was carried out at different Magnification. The Carr s index and angle of repose of the pellets were also determined. b) Disintegration test: Treated bodies were stable that does not involve in disintegration and remain as such as, whereas untreated caps were disintegrats in few miniutes. c) Uniformity of weight Uniformity of all batches of the pulsincaps were found to be ranging from ±.84 to 31.55±.42 within the standard limit and passes the test.

56 216 d) Estimation of drug content Drug content was done by spectrophotometrically by measuring the absorbance at 272nm. It was found to be ranging from 98.28±1.14 to 11.25±.53. e) Swelling index of hydrogel plug Results of swelling index (water uptake) study cleared that order of swelling observed in formulation containing Carbapol and Karaya gum could indicate the rate at which the dosage forms can able to absorb water and swells. Pulsincap PC8 showed linear increasing in swelling. The higher swelling index was found for the tablets in combination with Karaya gum whereas highest swelling index was observed with hydrogel plug containing Carbapol. This indicates a linear relationship between swelling and viscosity of polymer. The swelling indexes were observed to be the lowest with tablets of PC9. This might be due to the fact that the concentration of Guar gum was very less as it was insufficient for swelling. Excipient used in all formulation of hydrogel plug was found to have significant influence over the swelling and erosion properties of the Plusincap. The conventional lubricants such as magnesium stearate and aerosil have tendency to leach out from the tablet when comes in contact with water while with water insoluble excipient, the swelling phenomenon was found to be dominating over the erosion, this might be the tendency of the polymer to form tight gel barrier around the hydrophilic matrix. Swelling index for tablets of PC8

57 217 showed in the range of are presented in Table 7.4 shown in Figure In vitro drug study Linearity was obtained from the standard curve of Bosentan in phosphate buffer ph 7.4, it indicates that the drug obeys Beer- Lambert s law in concentration range of 2-2µg/mL. In vitro drug study revealed that the Pulsincap PC8 has shown highest percentage of cumulative drug at the end of 12 th hour this might be due to presence of adequate concentration of polymer while the drug s were not satisfactory in other formulations with HPMC K15, Guar gum. The most probable fact behind these observations with all formulations other than PC9 was the concentration of polymer used in those formulations was not effectively influenced on the rate of drug. In vitro drug study was carried out over the Pulsincaps of Bosentan containing different proportion of HPMC K15, Carbapol, Guar gum, and Karaya gum, the effect of polymer was observed on drug. From the observation it was found that PC3 has shown drug range of % among its proportions, PC1 has shown drug range of % among its proportions, PC16 has shown drug range of % among its proportions, PC8 has shown drug range of % among its proportions, this was the highest drug among all Pulsincap formulations. The dissolution data are given in Table from 7.5 to 7.2 and the drug pattern with kinetics treatment were

58 218 depicted as Figure from 7.8 to The comparison of drug pattern of all matrix tablets of Bosentan is shown in Figure Treatment of dissolution data with kinetic model Dissolution data of all matrix Pulsincap formulations were subjected to the treatment of different kinetic equations, it was found to be that the drug pattern were best fitted with zero order equation and involves combination of polymer relation and consequently swelling. The 'n' value obtained with the application of Koresmeyer and Peppa s equation 18 was found to be.988 for PC8. This value indicates a non-fickian mechanism that may be attributed to swelling and dissolution of the polymeric matrix. The dissolution and kinetic data are given in Table from 7.5 to 7.2 and graphs are shown from 7.8 to From the dissolution profile of each formulation initial burst effect was observed to some extent this might be due to inherent characteristics of polymer matrix. The drug was not obtain when the study was performed using acid buffer ph 1.2 during trial dissolution study, this might be due to lack of drug solubility at acidic medium Stability study Overall observations from different evaluation studies such as drug-polymer interactions, evaluation of granules, physicochemical parameters, swelling index, and In vitro drug were carried out on all Pulsincap of Bosentan, the PC8 has shown optimum results. Based on the obtained results the best formulation was subjected for

59 219 further stability studies. The stability study was conducted as per ICH guidelines for the period of twelve months at ambient and accelerated temperature and humidity conditions of 25 C/6%RH, 4 C/75%RH respectively. The data of multiple batches were analyzed using linear regression, poolability tests and ANCOVA statistical modeling these were amenable to analysis for quantitative attributes with upper acceptance criteria of 11% and lower acceptance criteria of 9% of label claim. There was a significant difference in intercepts (Y= 1.94, 11.96, 1.9 for PC8) but no significant difference in slope.647 among the batches. The predicted shelf life of PC8 was found to be 27 months and percentage drug s were 96.63, and 91.57% after 6 th, 9 th and 12 th months respectively. It was observed that there was no substantial change in drug profile after twelve months. The stability study revealed that the Pulsincap of PC8 may be stable for the period of more than two years. The observed and calculated values are given in Table The residuals obtained from the calculated values are shown in Figure The predicted shelf life is shown in Figure The data of versus cumulative percentage drug profile are given in Table 7.22 and pattern were shown in Figure Conclusion The approach of the present study was to develop Pulsincap of anti hypertensive drug Bosentan using natural and synthetic polymers having desirable properties such as swelling, biocompatible

60 22 and biodegradable and proper utilization of polymer with minimized quantity, henceforth comparison of all designed formulation and evaluate the profiles of Pulsincap formulations. The results obtained in this study leads to the following conclusions. Formulation PC8 containing 4mg of Carbapol was found to a maximum of 97.63% at the 12 th hour. The drug from the PC8 formulation was found to follow zero order kinetics. It was also found linear in Higuchi s plot, which confirms that diffusion is one of the mechanisms of drug. The FTIR and DSC analysis reveals that there was a weak intermolecular interaction between drugs and excipients and these was no significant chemical interaction between drug and polymers. Comparison of HPMC K15, Guar gum, Karaya gum, the Pulsincap prepared by using Carbapol, has shown optimized drug. This revealed the fact that Carbapol with Bosentan as Pulsincap has shown comparable drug characteristics, thus it may have fair clinical efficacy. Hence, the formulation PC8 may fulfill the objectives of the present study. It was concluded that the designed Pulsincap formulations may hold promise for further comparison studies.