JJT University, Rajasthan Page 62

Transcription

1 Aim of the Present Work There are several types of gastro retentive system but among of all these system gastro retentive floating drug delivery system had major advantages. In these system the active content embedded in the dosage form and having a desired release mechanism with buoyancy on to the gastric fluid. These type of dosage form float in the gastric environment without effecting the gastric emptying rate and so the dosage form remain in the gastric environment for longer period of time. During the floating stage the active content release from the dosage form at specified time and rate in the gastric environment. 1 Orally delivered biguanide for example Metformin Hydrochloride vastly utilized in the treatment of non insulin dependent diabetis mellitus. Metformin Hydrochloride improves insulin sensitivity in liver and muscle and so enhance glycemic control. Orally delivered biguanide has application on cardiac disease like insulin resistance, fibrinolytic abnormalities, plasminogen activator inhibitor, dyslipidemia etc. 2, 3 Metformin Hydrochloride have half life of four hours to six hours which incompletely absorbed and excreted in the urine. 4 Metformin Hydrochloride is protonated under strong physiological condition its pka is around 11.5 and is a strong base. The absorption pattern of Metformin Hydrochloride had been affected by negatively charged intestinal epithelium. 5 Metformin Hydrochloride have saturable dose dependent mechanism and its absorption is in the small intestine. 6 A modified release dosage form generally release the active content in the colon. So as per this the absorption window should be in colon or throughout the complete gastrointestinal tract. Some scientist done research and concluded that absorption window of Metformin Hydrochloride is low in the colon. 6,7 So if the Metformin Hydrochloride release in the small intestine have no pharmacological action and low therapeutic value. After the research it had been concluded that if the dosage form like gastro retentive tablets of Metformin Hydrochloride when administered there in sudden change in the mean bioavailability of Metformin Hydrochloride increase to 115 % which is quite high when compare to immediate release formulation of Metformin Hydrochloride. 8 JJT University, Rajasthan Page 62

2 For the control of diabetes mellitus, type 2 third generation sulfonyl urea drug is useful like Glimepiride. A drug substance like Glimepiride have several advantage when compared to other sulfonyl urea. Thus as per the discussion a drug i.e. Metformin Hydrochloride would be an ideal candidate for the floating drug delivery system. It is also more suitable when its pharmacokinetic and pharmacodynamic properties are discussed. In the current formulation development an attempt was made to design, development and evaluate Gastro retentive floating drug delivery system of metformin hydrochloride. Our aim behind this formulation development is to development of delivery that release the drug for longer period of time and at controlled rate and floating of the same for more than eight hours. When there is increase in the blood sugar level that is caused due to type two diabetes a patient should be given dose of Glimepiride and Metformin Hydrochloride in combination. The pancreas released the insulin after the meal so the body store the extra sugar. When the human being is suffering from type two diabetes the human body does not work properly to store the extra sugar and thus the sugar remains in the body for the longer period of time. So by this when there is increase in the blood sugar level it leads to the serious problem. When the combination of Metformin Hydrochloride and Glimepiride given simultenously it will give better pharmacological effect and it will help to the patient against high blood sugar level. 9 In the immediate release layer Glimepiride is given for the immediate pharmacological action for the control of the extra sugar. In the initial stage the blood sugar level is controlled by Glimepiride and after that the blood sugar level is maintained by controlled release layer of Metformin Hydrochloride. So if both the active content is given in single dose it will improve patient compliance. So, efforts are made to prepare such modified release dosage form. 10 In the oral traditional dosage form most of the drug content from the dosage form at colon, so an active content should have absorption window in the colon or the absorption through out the gastrointestinal tract. When the Metformin Hydrochloride release after the small intestine there is no pharmacological effect on the patient. 11 JJT University, Rajasthan Page 63

3 Thus there is a strong need to develop gastro retentive formulation containing Metformin Hydrochloride which is released in the gastric environment before passing the absorption window Objectives of the present study By using the Hypromellose and carbopol as sustained release polymers it will increase gastric resistande time and so resulting into the prolonged drug delivery system. The effect of various process and formulation variable that effects the release of the active content. Selection of polymer that has pronounced effect on the tablet properties and drug release. Development and evaluation of bilayer floating tablets of Metformin Hydrochloride and Glimepiride based on low density copolymer that keep the dosage form in the gastrointestinal tract. JJT University, Rajasthan Page 64

4 4.1.2 Principles to achieve goal Tablets should have satisfactory physical properties. Tablet release more than 90% of drug within 8 hours. Floating lag time of drug delivery system is reduced to minimum. Tablet remains buoyant for 8 hours in the gastrointestinal tract and also release the active content in the modified manner. 4.2 Preliminary Trials When designing gastro-retentive solid oral dosage form care should be taken for the its floating lag time. Floating lag time mainly depends on the density of the dosage form and gas generation property of the dosage form. Usually low density polymer like hypromellose utilized in the development of the floating drug delivery system. When the hypromellose comes in contact with the media it dissolve and form the gelling surface. It form gel boundry around the dosage form. By utilizing various grade of hypromellose desired rate of release and desired floating lag time can be achieved. Methodology Metformin Hydrochloride were utilized in the modified release layer and Glimepiride is taken in the immediate release layer for the gastro resistance bilayer tablets. Immediate release layer blend preperation Glimepiride, red iron oxide and sodium starch glycollate were sifted through 100 # and blended in the blender for five minutes at 24 RPM. Lactose DCL 15, microcrystalline cellulose ph 102 were sifted through 30 # and then these blend is added to the above mixed blend and mix for five minutes at 24 RPM. Magnesium stearate were sifted through 40 # and then add the magnesium stearate to the above blend in the blender for five minutes at 24 RPM. By doing the mixing of the blend in above manner there is minimizing in the deviation of content uniformity. The weight of immediate release tablets were kept fix at 150 mg per tablet. JJT University, Rajasthan Page 65

5 Sustained release layer preperation For the preparation of sustained release layer various different polymer were used. Different excipient like hypromellose K4M, Hypromellose K100M, sodium carbonate, potassium carbonate, sodium bicarbonate, calcium carbonate, Guar gum, sodium carboxy methyl cellulose, sodium alginate, stearic acid, various grade of carbopol were sifted through 40 # and then mixed with metformin Hydrochloride and stated quantity of previously sifted dibasic calcium phosphate dehydrate in blender for five minutes at 24 RPM. Sift talc through 40 # and mixed with above blend in the blender for five minutes at 24 RPM. Sift magnesium stearate through 40 # and then mix the sifted magnesium stearate to the above mixed blend for five minutes at 24 RPM. Compression of Bilayer Tablets Granules of both layer i.e. immediate layer and sustained release were compressed at 19.5 mm x 9.5 mm size caplet punches and corresponding dies on the bilayer compression machine. (Cadmach, Ahmadabad). Physical characterization of tablets Weight variation At the inprocess time during compression the tablets weight individually and average of twenty tablets had also been weight. These had been performed on all the batches compressed. From the resultant data average weight, relative standard deviation, standard deviation had been calculated. The compression machine was adjusted in such a way that it produce the tablets without weight variation. Tablet thickness During the inprocess stage in compression when the weight variation found in limit the thickness was measured. Ten pre weighed tablets were taken and thickness were measured by using dial hand micrometer. The average thickness, relative standard deviation, standard deviation were reported. JJT University, Rajasthan Page 66

6 Tablets hardness In the measurement of hardness the crushing strength of the tablets is measured. It gives the tablets breaking force and the strength of the physical tablets are represented by the hardness. Hardness was measured using a Dr. Scheleuniger s hardness tester. Hardness to be measured of ten tablets. The harness were measured in newton. The average hardness, relative standard deviation, standard deviation were reported. The hardness of the tablets were measured during start and between the compression. Friability Friability were carried out to determine the loss of mass when the tablets were subjected in the friability test apparatusat 25 RPM for four minutes i.e 100 RPM. The friability Friability were conducted in van Kel tablet friabilitor. For the friability test twenty tablets were selected from each batch and weighed and subjested to friability test. After the completion of test the dust were removed and tablets were re weighed. The percent loss mass were calculated. Floating lag time The floating behavior were studied to determine the floating lag time. The floating behavior were studied by placing the tablets in approximately thousand ml beaker fill up with five hundredml of 0.1 N Hydrochloric acid temperature of around 37.5 degree. The floating lag time is the time between the placing of tablets in the medium and the time up to which the tablets remain float in the media. Dissolution The dissolution was carried out to study the in vitro drug release of the prepared bilayer gastro retentive solid oral dosage form. The dissolution was carried out in basket apparatus i.e. type 1. The dissolution were carried out in acidic media with ph N HCl 900 ml with 0.1 % w/v of sodium lauryl sulphateand then followed by alkaline media with ph 6.8 phosphate buffer at 100 RPM. Dissolution sample were analysed by high performance liquid chromatography. JJT University, Rajasthan Page 67

7 Chromatographic condition in HPLC ; Mobile phase : 50: 50 of 10 Mol phosphate buffer ph 2.5 : Acetonitrile Column : C8 Loop size : 20 Detector : UV detection Wavelength : 228 nm Solution of Glimepiride and metformin Hydrochloride were prepared in 0.1 N NaOH as 1 mg/ml. Calibration curve were prepared from each analyte. The regression of the obtained curve were used to calculate the drug content and in vitro drug release. Drug Content 12 For the determination of drug content in each tablets twenty tablets were taken and crushed to fine powder with pastel and mortal. The 1.15 gram of powder were taken and diluted with alkali solution i.e 0.1 N NaOH up to 100 ml in the volumetric flask. The solution were subjected to sonification for fifteen minutes. Then these sonicated solution were filtrered through 0.45 micron filter paper. Then the solution were run to high performance liquid chromatography and finally calculated drug content of Metformin and Glimepiride. JJT University, Rajasthan Page 68

8 4.2.1 Optimization of drug: polymer ratio In preliminary trial batches, Hypromellose K4M and Hypromellose K100 M were selected. Viscosity of different polymer of Hypromellose K4M and Hypromellose K100M are four thousand cp and one lac cp, respectively. Table 4.1 Formulation of Metformin HCl and Glimepiride Excipients Batch No.# A1 A2 A3 A4 Layer 1 Metformin HCl Hypreomellose K 100M Hypromellose K4M Dicalcium phosphate dihydrate Avg. wt. of layer Layer 2 Glimepiride Lactose DCL Microcrystalline cellulose ph 102 Sodium starch glycollate Iron oxide red Avg. wt. of layer Total wt Floating lag time No floating No floating No floating No floating Layer -1: Talc 8.0 mg / tablet and Magnesium stearate 8.0 mg / tablet Layer 2: Magnesium stearate 2.0 mg / tablet JJT University, Rajasthan Page 69

9 Table 4.2 Physical and chemical evaluation Sr.No. Batch No. A1 A2 A3 A4 1 Description * * * * 2 Weight variation 944 mg to 939 mg to 938 mg to 941 mg to 960 (mg) 954 mg 951 mg 957 mg mg 3 Thickness (mm) 8.45 ± ± ± ± Hardness (N) 95 to to to to 97 5 Friability (%w/w) Assay Glimepiride (%) 7 Assay Metformin HCl (%) 8 Floating lag time No floating No floating No floating No floating (min) 9 Dissolution Glimepiride (%) Dissolution - 10 Metformin HCl (%) 1 Hour Hours Hours * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. JJT University, Rajasthan Page 70

10 Dissolution profile comparision % cumulative drug release B.No. A1 B.No. A2 B.No. A3 B.No. A times in hours Figure 8 Dissolution profile comparison for release of Metformin HCl from Bilayer tablets using HPMC K4M and HPMC K100M as polymer Results & discussion: (1) Floating properties of delivery system: Floating was not observed in any of the above batches. (2) In vitro Release properties of delivery system: The drug release profile of different formulation i.e. A1 to A4, formulated by utilizing Hypromellose K4M and K100M, are illustrated in table: 4.2. The dissolution profile shows biphasic release of active with rapid loading dose followed by slower release in another phase which is controlled by polymer. Due to different viscosity grade of polymer utilized there is difference in drug release observed. In the formulation where Hypromellose K4M utilized which is low viscosity polymer shows a faster release at initial time points. So by utilizing the Hypromellose polymer which is hydrophilic in nature and showing fast hydration the dissolution profile can be controlled. JJT University, Rajasthan Page 71

11 Conclusion: Dissolution profile of batch: A1 and A2 having drug (Metformin HCl): polymer ratio 1:0.25 and 1:0.5 respectively in giving controlled drug delivery were nearly similar. Hence, 1:0.25 drug (Metformin HCl) to HPMC K100M was used for further study. Release of active content from the dosage form it had been observed that due to high solubility of Metformin hydrochloride (BCS Class-III), HPMC K4M could not retard the release rate sufficiently to get the active content release from the dosage form at regulated rate but HPMC K100M could. Thus, high viscosity grade HPMC K100M was selected for study. It can be concluded that viscosity is playing the major role in active content release from the tablets. The ingredientwith high viscosity when utilized it prevents the initial rapid release of the drug but later on it does not have any effect on the release rate of the active content Use of gas-generating agents It is well known that gas-generating agents form CO 2 gas in HCl that entrapped into the polymeric gel network results in the decrease in the density of the dosage unit and so it it floats on the medium. If the gas generating agent comes in the contact of acidic environment of stomach it generates carbon dioxide and is protected and trapped in the gel layer which is formed by polymer and due that the density of dosage form comes below one. Due to these reason the dosage form remain buoyant in the media. Thus, we decided to incorporate gas-generating agent in the above formulation and optimize it for floating lag time using various gas-generating agent with different concentration. To study the effect of various gas-generating agents in the formulation of GRDDS, sodium bicarbonate, potassium carbonate, calcium carbonate and sodium carbonate were incorporated with 7.5 % w/w concentration of sustained release layer. Formulation of batches B1-B4 are mentioned in table 4.3. JJT University, Rajasthan Page 72

12 Table 4.3 Formulation of Metformin HCl and Glimepiride Excipient Batch No. # B1 B2 B3 B4 Layer 1 Metformin Hydrochloride Hypromellose K100M Sodium bicarbonate Sodium carbonate Potassium carbonate Calcium carbonate Dicalcium phosphate dihydrate Avg. wt. of layer Layer - 2 Glimepiride Lactose Microcrystalline cellulose ph 102 Sodium starch glycollate Iron oxide red Avg. wt. of layer Total weight Floating lag time Layer 1 : Talc 8.0 mg / tablet and Magnesium stearate 8.0 mg / tablet Layer 2 : Magnesium stearate 2.0 mg / tablet JJT University, Rajasthan Page 73

13 Table 4.4 Physical and chemical evaluation Sr.No. Batch No. Test B1 B2 B3 B4 1 Description * * * * 2 Weight variation 950 mg to 938 mg to 948 mg to 944 mg to (mg) 957 mg 959 mg 960 mg 959 mg 3 Thickness (mm) 8.45 ± ± ± ± Hardness (N) 95 to to to to Friability (%w/w) Assay Glimepiride (%) 7 Assay Metformin HCl (%) 8 Floating lag time (min) 9 Dissolution Glimepiride (%) Dissolution - 10 Metformin HCl (%) 1 Hr Hrs Hrs * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. JJT University, Rajasthan Page 74

14 Dissolution profile comparision 120 % cumulative drug release B.No. B1 B.No. B2 B.No. B3 B.No. B times in hours Figure 9 : Dissolution profile comparision for release of Metformin HCl from Bilayer tablets using different gas generating agent Result & discussion: Sodium bicarbonate gave least floating lag time. It was not desirable to use other gasgenerating agents as they exhibited more floating lag time, while our aim was to prepare dosage form with floating lag time less than minutes. Other gas-generating agents have slow reaction with hydrochloric acid hence; the reaction for CO 2 formation was slowed and results in higher floating lag time. Conclusion: Thus, it was concluded to use sodium bicarbonate which gave least floating lag time. Thus, because of sodium bicarbonate is superior over other it was selected for further studies. JJT University, Rajasthan Page 75

15 4.2.3 Optimization of gas generating agent To optimize the concentration of sodium bicarbonate it has been used in varying concentration from 5 %, 7.5 %, 10 % of the sustained release layer. Formulation of batches C1, B1 and C3 is mentioned in Table 4.5: Table 4.5 Formulation of Metformin hydrochloride and Glimepiride Ingredients Batch No. # B1 C1 C2 Layer 1 Metformin Hydrochloride Hypromellose K100 M Sodium bicarbonate Dicalcium phosphate dehydrate Avg. wt. of layer Layer 2 Glimepiride Lactose DCL Microcrystalline cellulose ph 102 Sodium starch glycollate Iron oxide red Avg. wt. of layer Total weight Floating lag time Layer 1 Talc 8.0 mg /tablet and Magnesium stearate 8.0 mg / tablet Layer 2 Magnesium stearate 2.0 mg / tablet JJT University, Rajasthan Page 76

16 Table 4.6 Physical and chemical evaluation Sr.No. Batch No. B1 C1 C2 Test 1 Description * * * 2 Weight variation (mg) 950 mg to mg to mg to 954 mg mg mg 3 Thickness (mm) 8.45 ± ± ± Hardness (N) 95 to to to Friability (%w/w) Assay Glimepiride (%) Assay Metformin HCl (%) 8 Floating lag time (min) Dissolution Glimepiride (%) 10 Dissolution - Metformin HCl (%) 1 Hr Hrs Hrs * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. JJT University, Rajasthan Page 77

17 Dissolution profile comparision % cumulative drug release B.No. B1 B.No. C1 B.No. C times in hours Figure 10 :- Drug release profile of Metformin Hydrochloride using sodium bicarbonate as gas generating with different concentration i.e 5 %, 7.5 %, 10 %. Result & discussion: By varying the concentration of gas generating agent there is change in the floating lag time which is mentioned in Table: 5. If the concentaration of gas generating agent increase there is decrease in lag time of the formulation. When there is introduction of suitable gas generating agent then it exhibits reduction in the floating lag time of the dosage unit. When dissolution profile study conducted it was observed that the release rate remained almost similar in all batches (table 6). It was reported that higher proportion of gas-generating agent showed higher bursting effect. To achieve least floating time and minimum bursting effect it is desirable to utilize gas generating agent in the optimum concentration. Conclusion: Sodium bicarbonate in concentration range % was use in further trials to get least floating lag time. At the time of compression when there is increase in the compaction force of tablets there will be decrease in the porosity of tablets and leads to penetration of water and alters the JJT University, Rajasthan Page 78

18 floating lag time. So, in such instances it is desirable to go with 10 % sodium bicarbonate to get lower floating time in presence of the other ingredients Effects of other gel-forming agents Other gel-forming agents, such as sodium carboxymethylcellulose, guar gum and sodium alginate were tried in place of HPMC for controlled drug delivery of Metformin hydrochloride. To study the effect of other gel-forming agents, guar gum, sodium alginate and sodium carboxymethylcellulose was incorporated in place of HPMC K 100M in the formulation as shown below in Table: 4.7. Table 4.7 Formulation of Metformin HCl and Glimepiride Ingredients Batch No. # D1 D2 D3 Layer 1 Metformin hydrochloride Sodium bicarbonate Guar gum Sodium alginate Sodium carboxy methyl cellulose Dicalcium phosphate dihydrate Avg. wt. of layer Layer 2 Glimepiride Lactose DCL Microcrystalline cellulose ph Sodium starch glycollate Iron oxide red Avg. wt. of layer Total weight Floating lag time (min) 8 Erosion and bursting Layer 1 : Talc 8.0 mg / tablet and Magnesium stearate 8.0 mg / tablet Layer 2 : Magnesium stearate 2.0 mg / tablet Erosion and bursting JJT University, Rajasthan Page 79

19 Table 4.8 Physical and chemical evaluation Sr.No. Batch No. D1 D2 D3 Test 1 Description * * * 2 Weight variation (mg) 939 mg to mg to mg to 951 mg mg mg 3 Thickness (mm) 8.45 ± ± ± Hardness (N) 89 to to to Friability (%w/w) Assay Glimepiride (%) Assay Metformin HCl (%) 8 Floating lag time (min) 8 Erosion and Erosion and bursting bursting 9 Dissolution Glimepiride (%) Dissolution - Metformin HCl (%) Hr. 4 Hrs Hrs * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. JJT University, Rajasthan Page 80

20 Dissolution profile 120 % cumulative drug dissolve B.No. D times in hours Figure 11: Dissolution profile for release of Metformin HCl from Bilayer tablets using guar gum as release retarding agent. Result & discussion: Batch D1 showed least floating lag time with good controlled release of active content from the matrix prepared using polymer guar gum. Tablets of batch D2 and D3 disintegrated within 3 min. Formulation development using release retarding agent as sodium carboxymethyl cellulose and sodium alginate could not retard the release rate of drug and burst immediately. Conclusion: Guar gum in higher concentrations or incorporation of release retarding agents might provide drug retaining property for longer period of time. Sodium alginate and sodium carboxymethylcellulose could not give satisfactory result. It may be due to less gel forming property and more hydrophilicity of these polymers. Formulation with guar gum does not have sufficient strength when compared to hypromellose, entrapment of carbondioxide and providing stable floating lag time. JJT University, Rajasthan Page 81

21 4.2.5 Addition of release retarding agent (stearic acid) Stearic acid was used as hydrophobic agent and it was incorporated with drug using chloroform solution. First make complex of drug with stearic acid by chloroform and then add other ingredients, mix well and compressed it. Stearic acid was used for sustaining the release of Metformin hydrochloride at 1, 2 and 3% of SR layer. Formulation of batches E1-E3 is mentioned in table 4.9. Table 4.9 Formulation of Metformin HCl and Glimepiride Excipients Batch No.# E1 E2 E3 Layer 1 Metformin Hydrochloride Hypromellose K 100 M Sodium bicarbonate Stearic acid Dicalcium phosphate dihydrate Avg. wt. of layer Layer 2 Glimepiride Lactose DCL Microcrystalline cellulose ph Sodium starch glycollate Iron oxide red Average wt. of layer Total wt Floating lag time (min) Layer 1 : Talc 8.0 mg / tablet and Magnesium stearate 8.0 mg / tablet Layer 2 : Magnesium stearate 2.0 mg / tablet JJT University, Rajasthan Page 82

22 Table 4.10 Physical and chemical evaluation Sr.No. Batch No. E1 E2 E3 Test 1 Description * * * 2 Weight variation (mg) 942 mg to mg to mg to 951 mg mg mg 3 Thickness (mm) 8.45 ± ± ± Hardness (N) 90 to to to Friability (%w/w) Assay Glimepiride (%) Assay Metformin HCl (%) 8 Floating lag time (min) Dissolution Glimepiride (%) Dissolution - Metformin HCl (%) Hr. 4 Hrs Hrs * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. JJT University, Rajasthan Page 83

23 Dissolution profile comparision 80 % cumulative drug dissolve B.No. E1 B.No. E2 B.No. E times in hours Figure 12: Dissolution profile comparision for release of Metformin HCl from Bilayer tablets using stearic acid as release retarding agent with different concentration i.e 1 %, 2 %, 3 %. Result & discussion: It appears that the incorporation of stearic acid had not much effect on release of Metformin hydrochloride (end point not achieved) from the GFDDS compared with batch B1 containing same composition without stearic acid. Conclusion: By addition of stearic acid it showed incomplete release in dissolution. Thus, it was concluded that incorporation of stearic acid had not much benefit and hence; it was decide to use Carbopol 940 P with HPMC to obtain desired drug release. JJT University, Rajasthan Page 84

24 4.2.6 Addition of release retarding agent (carbopol) To overcome the burst effect and to improve the retardation in the drug release, release retarding agents were added to the formulation. When hypromellose and Carbopol utilized simultaneously in a mucoadhesive drug delivery system it improves the mucoadhesive property of the dosage form. 13,14 The total amount of the media imbibed in the Carbopol is much lower when the same is compared with Hypromellose. It was investigated using model drug propranolol hydrochloride. 15 In the formulation the polymer hypromellose and carbopol can be utilized extragranular to avoid contact with granulating fluid for the aid in compaction force. 16 Carbopol 934P and Carbopol 940P were used with HPMC. The formulation of these batches E4-E5 is mentioned in Table 4.11: JJT University, Rajasthan Page 85

25 Table 4.11 Formulation of Metformin HCl and Glimepiride Excipients Batch No. E4 E5 Layer 1 Metformin Hydrochloride Hypromellose K100M Hypromellose K4M - - Sodium bicarbonate Carbopol Carbopol Di calcium phosphate dihydrate Avg. wt. of layer Layer 2 Glimepiride Lacvtose DCL Microcrystalline cellulose ph Sodium starch glycollate Iron oxide red Magnesium stearate 2 2 Avg. wt. of layer Total weight Floating lag time (min) 2 3 Layer 1 : Talc 8.0 mg / tablet and Magnesium stearate 8.0 mg tablet JJT University, Rajasthan Page 86

26 Table 4.12 Physical and chemical evaluation Sr.No. Batch No. E4 E5 Test 1 Description * * 2 Weight variation (mg) 948 mg to 959 mg 943 mg to 957 mg 3 Thickness (mm) 8.49 ± ± Hardness (N) 91 to to Friability (%w/w) Assay Glimepiride (%) Assay Metformin HCl (%) Floating lag time (min) Dissolution Glimepiride (%) Dissolution - Metformin HCl (%) 1 Hr Hrs Hrs * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. Dissolution profile comparision 120 % cumulative drug dissolve B.No. E4 B.No. E times in minutes Figure 13: Dissolution profile comparision for release of Metformin HCl from Bilayer tablets using Carbopol 934 P and Carbopol 940 P as release retarding agent. JJT University, Rajasthan Page 87

27 Result & discussion: From the conducted experimental trial it had been reveals that by utilizing the different grade of carbopol there is change in drug release profile of Metformin Hydrochloride in the dosage unit when compared with dosage unit without carbopol i.e. Batch B1. Carbopol is not soluble in simulated gastric fluid and purified water at normal testing condition. 17 In the trial where carbopol not utilized it exhibit rapid release at the initial time points that might be due to crosslinking. When the formulation comes in direct contact with the media or water the polymer swells and retain in the micro gelling network. Thus there is deliver of active content at specific rate in the intestine and would enhance absorption. Presence of Carbopol 940 gave good release retarding of metformin hydrochloride compared to Carbopol 934 (Batch-E5) and without Carbopol (Batch-B1). Conclusion: The usage of carbopol in the formulation development provide specific release and buoyancy of tablets. It also provide another property like gastric retention to maintainthe dosage form in the gastrointestinal tract. Thus, the approach of combination of Carbopol 940 with HPMC was used. JJT University, Rajasthan Page 88

28 4.3.1 Accelerated Stability Study of The Optimized Batch : As per the regulatory requirement there is a need of performing the stability study of the finalized formulation which is to be meant for marketing and consumer drug product. So there is need of sound stability schedule for the dosage form which give the effect of temperature and humidity. The product should be safe and efficacious through the shelf life provided. All the different countries have different geographical condition and different environmental condition. So they have their own regulatory agency. The finalized formulation were packed in the blister pack. Which should be intended marketing pack. Packed tablets were charged for accelerated stability condition at 40 0 C/75% RH. There should not be any change in physical attributes and chemical attributes of the dosage form. There should not be any change in floating lag time throughout the shelf life and neither change in the dissolution profile of drug release. Dose dumping and failure of floating of dosage form are probable effect for such types of dosage form. Packed sample were evaluated after three month of accelerated stability condition. Buoyancy study and drug release from dosage form were carried out. Stability study data of formulation is mentioned in table 4.13 Table 4.13 Accelerated stability study data Time in minutes Cumulative % Drug release Initial After 3 months Floating lag time (min) 3 4 Dissolution Glimepiride (%) Dissolution - Metformin HCl (%) - 1 Hr Hrs Hrs F JJT University, Rajasthan Page 89

29 Dissolution profile comparision 120 % cumulative drug release B.No. E5 (Initial) B.No. E5 (40/75-3M) times in hours Figure 14: Dissolution profile comparision for release of Metformin HCl from Bilayer tablets of optimized batch with initial and 40/75 3M. The dissolution profile of optimized formulation had been carried out and compared. It had been compared by mathematical equation called similarity and dissimilarity factor. The similarity factor represented by F2 represent the similarity of the formulation. If the F2 is more then 50 then the formulations are considered to be similar. The performed dissolution shows the similarity 77.2 which is indicating the good similarity of the formulation. There is also no change in the buoyancy study lag time of the dosage form. So, the finalized formulation reveals good stability. JJT University, Rajasthan Page 90

30 4.4.1 Result and discussion: The dosage form with different formulation were analysed with different physical and chemical parameters. Physical parameters include uniformity of weight, thickness, tablets breaking force, friability etc. and chemical parameters include dissolution and drug content. Uniformity of weight found well within the limit. Thickness and hardness of the tablets were found to be uniform. Friability of the evaluated batches were found bellow 1 % w/w. Drug content of all the are also found well within the limit. In Batch No. A1, A2, A3, A4 no floating observed. In Batch No. D2 and D3 erosion and bursting observed. Floating lag time is more than 20 minutes in Batch No. B2, B3 and B4. No complete release in dissolution was observed in Batch No. E1, E2, E3. For the optimization of sodium bicarbonate Batch No. C1 and C2. Carbopol 934 is evaluated in Batch No. E4. In Batch No. E5 Carbopol 940 is used Conclusion: In the present investigation development is carried out for Bilayer floating tablets using Glimepiride and Metfromin Hydrochloride. Glimepiride is used in immediate release layer and Sustained release layer of Metformin Hydrochloride is prepared. In the immediate release layer sodium starch glycolate is taken as super disintegrant. In the preparation of bilayer floating tablets Sodium bicarbonate is finalized for gas generating agent as its floating lag time is less compare to other salt and the qty. of sodium bicarbonate is also optimized to 60.0 mg. Hypromellose is used as rate controlling agent. From all the above developed formulation it had been concluded that Batch No. E5 has less floating lag time and sustained release of Metformin Hydrochloride and Glimepiride as immediate release component. Batch No. E5 shows better stability in accelerated condition. JJT University, Rajasthan Page 91

31 4.5.1 In Vivo buoyancy study In Vivo studies of gastro retentive floating dosage form In vivo study was performed to optimized formulation of one of the batch: E5 by further modifying formulation to incorporate X-ray grade Barium sulphate as X-Ray opaque substance. Initial formulation trials were made by replacing metformin hydrochloride with X-ray grade Barium sulphate. Relative high density, aqueous insolubility and poor buoyancy properties were the limiting factor to achieve desired floating lag time of prepared formulation. Part of metformin hydrochloride was replaced by Barium sulphate. The composition of optimized formulation is mentioned in table Table 4.14 Formulation of Metformin Hydrochloride and Glimepiride Excipients Batch No.# E6 Layer 1 Metformin hydrochloride HPMC K 100M Barium sulphate Sodium bicarbonate 60.0 Carbopol Dicalcium phosphate dihydrate 59.0 Avg. wt. of layer Layer 2 Glimepiride 1.0 Lactose DCL Microcrystalline cellulose ph Sodium starch glycolate 8.0 Iron oxide red 1.0 Avg. wt. of layer Total weight Floating lag time (min) 4 JJT University, Rajasthan Page 92

32 Table 4.15 Physical evaluation Sr.No. Batch No. E6 Test 1 Description * 2 Weight variation (mg) 940 mg to 960 mg 3 Thickness (mm) 8.39 mm ± 0.2 mm 4 Hardness (N) 95 to Friability (%w/w) 0.18 % w/w 8 Floating lag time (min) 4 * Capsule shape, Biconvex, Bilayer, uncoated tablet with White to off white one layer and pink other layer. The amount of X-Ray opaque material was determined experimentally so that it is visible in X-Ray screening technique but it does not show its effect to buoyancy of the dosage form. At the same time the amount of BaSO 4 should not be high enough to cause sinking of tablets in stomach In-Vivo Study In Vivo study had been carried out by taking the bilayer floating dosage form to a human volunteer (Male 31 years, 67 kg weight). The study was conducted in fasting state. The subject was swallowed the bilayer floating tablets containing barium sulphate with 250 ml of purified water. Afterwards subject was not allowed to eat during the entire study. After the swallowing of the dosage form the subject allowed to drunk the water after four hours. At the time of study conduction the subject remained in sitting or upright posture. The position of the bilayer floating tablets had been monitored by X-Ray screening technique. To view the position of the tablets after two hours and eight hours the radiography was conducted. Figure 15 and 16 represent the photograph of X-Ray screening technique of the formulation. JJT University, Rajasthan Page 93

33 Figure 15: X ray indicating photo of tablets after 2 hrs. JJT University, Rajasthan Page 94

34 Figure 16: X ray indicating photo of tablets after 7 hrs. Results and discussion: The results showed that tablet remained in floated condition in gastric content up to 7 hrs. A tablet without Barium sulphate is expected to float for longer duration of time than the test condition shown above since the density of Barium sulphate containing tablet will be higher than the tablet without it. Even if tablet crossed stomach area after 8 hours, the remaining drug will continuously absorbed from upper part of small intestine up to 12 hours without losing of drugs to waste. JJT University, Rajasthan Page 95

35 4.6 Referances :- 1) Prescott LC, Nimma WS., In rate control In Drug Therapy, 1985; 59. 2) Shinde AJ., Gastro retentive Drug Delivery System: An Overview, Pharmaceutical information, 2008; 6(1), ) Peters DH, Dunn CJ., Metformin. A review of its pharmacological properties and therapeutic use in non-insulin dependent diabetes mellitus, Drugs 1995; 49 (5), ) Scheen CJ., Clinical pharmacokinetics of Metformin, Clinical Pharmacokinitic, 1996, 30 (5), ) Stepensky D., Hoffman A., Stepensky D., Ftiedman., Preclinical evaluation of pharmacokinetic- pharmacodynamic rationale for oral CR metformin formulation, Journal of Control Release, 2001; 71, ) Vidon N., Chaussade S., Noel M., Franchisseur C., Huchet B., Bernier JJ., Metformin in the digestive tract, Diabetes Research and Clinical Practice., 1998; 4, ) Marathe PH., Wen Y., Norton J., Greene DS., Barbhaiya RH., Wilding IR., Effect of altered gastric emptying and gastrointestinal motility on metformin absorption, British Journal of Clinical Pharmacology; 2009, 50, ) Gusler G., Gorsline J., Pharmacokinetic of Metoformin in gastric retentive tablets in healthy volunteers, The Journal of Clinical Pharmacology, 2001; 41, ) Charpentier G., Fleury F., Kabir M., Vaur L., Halimi S. Improved glycaemic control by addition of Glimepride to Metformin monotherapy in Type 2 diabetic patients, Diabetic Medicine.2001; 18, ) Package Insert, Bristol Myers Squibb, GLUCOPHAGE/ GLUCOPHAGE XR June JJT University, Rajasthan Page 96

36 11) Stepensky D, Friedman M. Preclinical evaluation of Pharmacokinetic Pharmacodynamic rational for oral CR Metformin Formulation, Journal of Controlled Release 2001; 71, ) Bhaskar LK, Rant BB, Deo AA, Baqool MA, Shinde BR. Simultaneous determination of Metformin and Glimepride in pharmaceutical dosage form by reverse phase liquid chromatography, Journal of Separation Science October 2005; Volume 28, Issue 16, pages ) Khanna R., Agarwal SP., Ahuja A., Muco-adhesive buccal tablets of clotrimazole for oral candidiasis, Drug Development and Industrial Pharmacy., 1997; 23, ) Anlar S., Capan Y., Guven O., Gogus A., Hincal AA., Formulation and in vitro-in vivo evaluation of buccoadhesive morphine sulfate tablets, Pharm. Res. 1993; ) Perez MB., Ford JL., Armstrong DJ., Elliott PN., Hogan JE., Release of propranolol hydrochloride from matrix tablets containing HPMC K4M and Carbopol 974, International Journal of Pharmaceutical Science., 1994; 111, ) Durrani MJ., Whitaker RF., Manji PA., Novel wet granulation method for Carbopol resin. Part 1. Extragranular addition, Drug Development of Industrial Pharmacy 1997; 23, ) Li S., Lin S., Daggy BP., Mirchandani HL., Chien YW., Effect of HPMC and carbopol on the release and floating properties of gastric drug delivery sytem using factorial design, International Journal of Pharmaceutical Science. 2003; 253, JJT University, Rajasthan Page 97