35 P a g e International Standard Serial Number (ISSN): 2319-8141 International Journal of Universal Pharmacy and Bio Sciences 2(6): November-December 2013 INTERNATIONAL JOURNAL OF UNIVERSAL PHARMACY AND BIO SCIENCES IMPACT FACTOR 1.89*** ICV 3.00*** Pharmaceutical Sciences RESEARCH ARTICLE!!! FORMULATION AND EVALUATION OF SUBLINGUAL TABLETS OF OXAZEPAM Gangadhara Rao. K* 1, Lakshmana Rao Potti 1, Rama Kotaiah. M 1, Prasada Rao.M 1, Siva Sankar.R.Beera valli 2, Kameswara Rao.S 3. *1 Department of Pharmaceutics, M.A.M College of Pharmacy, Kesanupalli, Narasarao Pet, Guntur (dt), Andhra Pradesh, India. 2 Fredrick Burg, Virgina. 3 Srisiddhartha Pharmacy College, Nuzivid. KEYWORDS: Oxazepam, Croscarmellose, Sodium Starch Glycollate, Crospovidone. For Correspondence: Gangadhara Rao.K Address: Department of Pharmaceutics, M.A.M college of Pharmacy, Kesanupalli, Narasarao Pet, Guntur(dt),Andhra Pradesh, India. Email-ID: ramavathnag@gmail.com ABSTRACT The objective of the current study was to develop and optimize a sublingual tablet of Oxazepam which is an effective drug in the treatment of anxiety and insomnia. Oxazepam containing tablets were prepared by direct compression method using different superdisintigrents such as Crosspovidone, Sodium Starch Glycollate, Crosspovidone. The tablets were evaluated for both pre compressional parameters like bulk density, tapped density, angle of repose, compressability index and hausners ratio and post compressional parameters like Hardness, Weight variation, Thickness, Friability, Drug content, Wetting time, Water absorption ratio, In-vitro disintegration time, In-vitro dissolution study and also Drug release kinetic study. The Hardness, Weight variation, Thickness, Friability and Drug content of tablets were found to be acceptable according to pharmacopoeial limits. An optimized tablet formulation i.e. F 3 was found, which provided short wetting time of 19 sec and In-vitro disintegration time of 17 sec. From the above results, it indicated that the amount of superdisintegrant i.e. sodium starch glycollate was significantly affected the dependent variables like wetting time and In-vitro disintegration time. The best in-vitro drug release was found to be in Batch.No.3 i.e.101.75% during the end of 15 th min. The in-vitro drug release data of all oxazepam sublingual tablets were subjected to goodness of fit test by linear regression analysis according to Zero order equation, Ist order equation, Higuchi s equation and Krosmeyer-Peppas equation to ascertain the mechanism of drug release. Hence the drug release followed the Ist order release kinetics with diffusion mechanism. Compatability studies reveal that there was no interaction between the drug and polymers. The tablets showed no significant change either in physical appearance or in dissolution pattern after storing at room temperature, 45 C, 37 C, 40 C/ 75% RH.
- 36 - P a g e International Standard Serial Number (ISSN): 2319-8141 INTRODUCTION: Tablets that disintegrate or dissolve rapidly in the patient s mouth are convenient for young children, the elderly and patients with swallowing difficulties, and in situations where potable liquids are not available. For these formulations, the small volume of saliva is usually sufficient to result in tablets disintegration in oral cavity. The medication can then be absorbed partially or entirely into the systemic circulation from blood vessels in the sublingual mucosa, or it can be swallowed as a solution to be absorbed from gastrointestinal tract. The sublingual route usually produces a faster onset of action than orally ingested tablets and the portion absorbed through sublingual blood vessels bypass the hepatic first pass metabolic processes. 1-3 Oxazepam 4 is used in the treatment of Anxiety and exerts its anxiolytic effects by potentiating the effect of gammaaminobutyric acid (GABA) on GABA-A receptors through a cooperative mechanism of action. The bioavailability of Oxazepam following oral administration is very low. Oxazepam is absorbed rapidly on oral administration. When administered orally, frequent dosing is needed due to its short biological half life. Secondly drug undergoes high hepatic first pass metabolism. Various techniques can be used to formulate rapidly disintegrating or dissolving tablets. 5,6 Direct compression is one of these techniques which require incorporation of a superdisintegrant into the formulation, or use of highly water soluble excipients to achieve fast tablet disintegration. Extremely fast tablets disintegration would be required to enhance the release of Oxazepam from tablets for rapid absorption by the sublingual mucosa blood vessels. It was decided that Oxazepam could be formulated into fast disintegrating tablets for sublingual administration as potential emergency treatment of anxiety. MATERIALS AND METHODS: MATERIALS: Oxazepam was obtained as a gift sample from sunpharma, Ahmedabad. Croscarmellose sodium, Crosspovidone XL-10, Sodium Starch Glycolate, Talc, mg stearate, mannitol, lactose, aspartame were procured from Hetero labs, jeedimetla. All the chemicals and solvents used were of analytical grade. METHOD: Oxazepam sublingual tablets prepared by the direct compression method using different excipients. Different concentration of excipients was used to prepare different group of sublingual tablets. Compositions of various formulations are shown in Table-1. All the ingredients were weighed accurately and passed through sieve # 40. Oxazepam was taken and was mixed with this all ingredients in geometrical ratio in polythene bag. Finally the talc was added and mixed thoroughly to get free flowing powder. The blends were compressed using 6.5mm standard concave punches.
F.No - 37 - P a g e International Standard Serial Number (ISSN): 2319-8141 OX MCC Table.No.1: FORMULATION TABLE LAC MAN DEX SSG CSS CPV TAL FLO Twt (mg) F 1 10 28-60.6-1 - - 0.2 0.2 100 F 2 10 28-59.6-2 - - 0.2 0.2 100 F 3 10 28-58.6-3 - - 0.2 0.2 100 F 4 10 28 - - 58.6 3 - - 0.2 0.2 100 F 5 10 28 58.6 - - 3 - - 0.2 0.2 100 F 6 10 28-57.6 - - 2 2 0.2 0.2 100 F 7 10 28 57.6 - - - 2 2 0.2 0.2 100 F 8 10 28 - - 57.6-2 2 0.2 0.2 100 F 9 10 28 - - 59.6-1 1 0.2 0.2 100 OX: oxazepam, MAN: Mannitol DC, LAC: Lactose, CPV: Crosspovidone XL-10. CSS: Crosscarmellose Sodium, SSG: Sodium Starch glycolate, DEX: Dextrose anhydrous, Twt: Total weight of Tablet, TAL: Talc, MCC: Microcrystalline cellulose PH 200, FLO: Flavor orange. Precompression parameters Properties of powder, which are of most importance, are Residual moisture content, Bulk density, Bulkiness, Hausner ratio and Compressibility index. These parameters were evaluated on a laboratory scale for optimum production with respect to quality and quantity. 1. Bulk density (Do): It is the ratio of bulk volume to the total mass of the powder taken. It is measured by pouring the weighed powder into a graduated cylinder and the volume was noted. It is given by Do = M/Vo Where M is the mass of powder, Vo is the Bulk Volume of powder; it is expressed in gm/ml. 2. Tapped density (Dt): It is the ratio of mass of the powder to the tapped volume of the powder. The tapped volume was measured by bulk density apparatus in which the powders were tapped for predetermined number of taps until the volume remained constant. It is given by Dt = M/Vt Where M is the mass of powders Vt is the tapped volume of powders; it is expressed in gm/ml. 3. Carr s index It indicates the ease, which a material can be introduced to flow. It is given by I = (Dt-Do/Do) x 100 Where Dt is tapped density Do is bulk density; it is expressed in terms of percentage. 4. Hausner ratio: It is the ratio of tapped density to untapped density. It is given by H = Dt/Do Where Dt is the tapped density of powders Do is the untapped density of powders.
- 38 - P a g e International Standard Serial Number (ISSN): 2319-8141 5. Angle of Repose: The angle of internal friction is a measure of internal stress distribution and is the angle at which an applied stress diverges as it passes through the bed. It is the least slope at which a powder will slide down an inclined plane surface. The typical method is to pour the powder in a conical heap on a level, flat surface and measure the included angle with the horizontal. It is denoted by q. tan q = h/r Where, q -angle of repose, h - height in cm, r - radius. The powder mixture was allowed to pass through the funnel fixed to a stand at definite height. The angle of repose was then calculated by measuring the height and radius of the heap of powder formed. Formu.No. Bulk Density (gm/ml) Table.No.2: Pre-compression parameters of all batches Tapped (gm/ml) Density Carr s Index Hausner Ratio Angle of Repose 01 0.5144 0.5896 14.61 1.1461 19 02 0.5102 0.5952 16.66 1.1666 18 03 0.5122 0.5814 14.03 1.1351 16 04 0.5208 0.5966 14.6 1.1455 14 05 0.5081 0.6053 19.13 1.1913 34 06 0.5091 0.5924 16.36 1.1636 17 07 0.5197 0.5966 14.79 1.1479 28 08 0.5144 0.5980 16.26 1.1625 19 09 0.5319 0.6024 13.25 1.1325 18 Post compression parameters 1. Hardness as per IP 7 The hardness of the tablet is a official Test for the tablets as per IP and it was determined for all the formulations by using Monsanto type hardness tester and the results shown in table.no.3. 2. Friability 7 The friability of the tablet is not a official test but as it is required for the shipment of the product, so it was carried out by using Friabilator. The 10 tablets were weight (W initial) and transferred into the friabilator. The friabilator was operated at 25 rpm for 4 minutes. Then the tablets were weighed again after friabilation (W final). And the results shown in table.no.3.the % friability was then calculated using the formula 3. Weight variation as per IP 8 % F= W initial W final W initial The weight variations of the sublingual tablets were carried out using 10 tablets by taking the Average weight of 10 tablets and the results shown in table.no.3.
- 39 - P a g e International Standard Serial Number (ISSN): 2319-8141 4. Thickness 7 The thickness of the tablet was measured by using digital vernier scale. The limit for this was average thickness ± 0.2mm and the results shown in table.no.3. 5. Disintegration time 10 The disintegration time for sublingual tablets was determined by using USP disintegration test apparatus. The limit for disintegration was not more than 2 minutes at 37 0 C. Procedure: Six tablets were placed individually in each tube of disintegration test apparatus and discs were placed. The water bath was maintained at 370 C ±_0.50C and the time taken for all tablets to disintegrate completely were noted and the results shown in table.no.3. 6. Wetting time 9 Wetting time was determined by placing a piece of tissue paper folded twice in small petridish having internal diameter of 6.5 cm. 10 ml of water was added. A tablet was placed on the paper and time for complete wetting of tablet was measured in seconds and the results shown in table.no.3. The photographs of wetting time of sublingual tablets were shown in fig.no.1 7. Assay 10 tablets weighed and triturated. The tablet triturate equivalent to 100 mg of the drug was weighed accurately, dissolved in Methanol and further dilutions were made using the same and the absorbance were measured at 295 nm against the reagent blank and the concentration of oxazepamin mcg/ml was determined using the regression equation and the results shown in table.no.3. Y = 0.036X Drug content in mcg / tab = conc. mcg / ml* dilution factor % drug content = drug content in mg* 100 / label claim. FORM.No. Hardness (kg/cm 2 ) Table.No.3: Post compression parameters Thickness (mm) Weight variation Friability Disintegration (Seconds) Wetting Time (Seconds) Assay w/w F 1 2.5 2.62 101.2 0.3412 38 52 93.51 F 2 4.0 2.67 99.8 0.0942 29 36 94.82 F 3 4.0 2.63 102.3 0.1970 17 19 95.91 F 4 4.0 2.63 100.2 0.0104 118 107 96.20 F 5 3.0 2.70 99.6 0.1023 17 24 95.04 F 6 3.5 2.64 99.8 0.3241 25 19 96.28 F 7 3.0 2.67 102.3 0.1226 21 19 96.50 F 8 4.0 2.67 98.4 0.0140 114 150 95.62 F 9 3.0 2.68 98.9 0.0462 46 25 95.11
- 40 - P a g e International Standard Serial Number (ISSN): 2319-8141 Initially Started wetting Swelling Fig.No.1: wetting images of sublingual tablets 8. Invitro dissolution study The dissolution was carried out to determine the rate of drug release at different time intervals. The sublingual tablets were subjected for dissolution study by using modified USP dissolution apparatus. The tablet was placed in the basket and the dissolution was carried out using Phosphate Buffer ph 6.8 as medium. Aliquots of 5ml were withdrawn at every 5 minutes interval and were replaced by same solution. The drug content was analyzed spectrophotometrically at 230nm against reagent blank. The results were shown in table.no.4. % Cumultive drug release and time curve dissolution graphs were visualized in fig.no.2 to 4 Time (min) F 1 Table.No.4: % Cumulative drug release profile of all formulations F 2 F 3 F 4 F 5 F 6 F 7 F 8 F 9 5 66.67 77.24 84.93 63.99 96.28 74.85 78.85 55.86 61.3 10 74.1 82.28 94.38 75.83 99.87 82.24 86.37 67.68 68.48 15 80.9 86.03 101.75 81.66 99.99 89 91.45 76.42 73.48 20 87.81 90.36-88.02-95.83 97.46 87.01 80.62 25 96.53 94.64-93.91-100.58 100.08 96.02 88.29 30 101.86 99.03-99.93 - - - 99.02 99.42
% CDR % CDR % CDR - 41 - P a g e International Standard Serial Number (ISSN): 2319-8141 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 time in min 1 2 3 Fig.No.2: Dissolution profiles of F. No 01-03, 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 time in min 4 5 6 Fig.No.2: Dissolution profiles of F. No 04-06, 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 time in min 7 8 9 Fig.No.3: Dissolution profiles of F. No 07-09
- 42 - P a g e International Standard Serial Number (ISSN): 2319-8141 DRUG RELEASE KINETICS: To examine the release mechanism of Oxazepam from the prepared sublingual tablets, the results were analyzed according to the following equation Where Mt / Mα is the fractional drug released at time t, k is a kinetic constant incorporating structural and geometrical characteristics of the drug/polymer system [device], and n is the diffusional exponent that characterizes the mechanism of drug release. It is known that for non-swelling tablets, the drug release can generally be expressed by the Fickian diffusion mechanism, for which n = 0.5, whereas for most erodible matrices, a zeroorder release rate kinetics is followed, for which n = 1. For non-fickian release, the n value falls between 0.5 and 1.0 [0.5 < n < 1.0]; whereas in the case super case II transport n >1. The data of the in-vitro release was fit into different equations and kinetic models to explain the release kinetics of Oxazepam from sublingual tablets. The kinetic models used were zero-order equation 12 (eq. 1), first-order equation 13 (eq. 2), Higuchi equation 14 (eq. 3) and Krosmeyer-Peppas equation 15 (eq. 4). Qt = K0t ----------- (1) Qt = Q0 (1- e-k1t) ----------- (2) Qt = KH.t1/2 ----------- (3) Qt / Q = Kk tn ----------- (4) Where, Qt ------- Is the amount of drug release in time t Q0 ------- Is the initial amount of the drug n ------- Exponent value And K0, K1, KH, and Kk are release rate constants for Zero-order, First-order, Higuchi, and Krosmeyer-Peppas model respectively. Zero order represents an ideal release profile in order to achieve the pharmacological prolonged action. This is applicable to dosage forms like transdermal systems, coated forms, osmotic systems, as well as matrix tablets with low soluble drugs. First order is applicable to study hydrolysis Kinetics and to study the release profiles of pharmaceutical dosage forms such as those containing water-soluble drugs in porous matrices. Higuchi Matrix is applicable to systems with drug dispersed in uniform swellable polymer matrix as in case of matrix tablets with water-soluble drug. Krosmeyer-Peppas equation is widely used; when the release mechanism is not well known or when more than one type of release phenomena could be involved. Data of the in-vitro release was fit into different equations and kinetic models to explain the release kinetics of Oxazepam from sublingual tablets. The data are presented in Table 06.
- 43 - P a g e International Standard Serial Number (ISSN): 2319-8141 Formulation No. Table 4: Regression analysis of Formulation No.1-9 Regression Coefficient Korsemeyer Peppas Zero order First order Higuchi F 1 0.9032 0.9834 0.9654 0.9649 F 2 0.8891 0.8954 0.9875 0.9485 F 3 0.9159 0.9452 0.9863 0.9830 F 4 0.9110 0.9750 0.9679 0.9636 F 5 0.9214 0.9654 0.9759 0.9751 F 6 0.9413 0.9826 0.9748 0.9625 F 7 0.8925 0.9212 0.9629 0.959 F 8 0.9089 0.9326 0.9547 0.9517 F 9 0.9234 0.9486 0.9738 0.9721 STABILITY STUDIES: The selected formulations were packed in the strip packaging, which were packed in the card board box and labeled. They were then stored at 45 C, 37 C, 40 C/ 75% RH and Room Temp. Kept for three months and evaluated for their physical appearance band drug release at specific intervals of time per ICH Guide lines. The values were shown in table.no.6 & table.no.7. TIME (MIN) Table.No.6: Dissolution Profile: B.No. 03 % Cumulative Drug Release Initial 30 Days 60 Days 90 Days 5 84.93 86.01 85.00 84.8 10 94.38 93.07 93.0 92.9 15 101.75 100.49 100.20 100.05 DISCUSSION: The sample of Oxazepam tested for physicochemical properties complies as per BP specifications. The estimation of Oxazepam by UV spectrophotometric method at λmax 230 nm in Methanol. The correlation coefficient for the standard curve was found to be 0.999, at concentration range, 0.5-18mcg/ml. The resulting tablets were evaluated considering the disintegration time as the main criteria. Initially the formulation was prepared by using different concentrations of crosscarmellose sodium and crosspovidone each individually, and the resulting tablet DT was found to be high. The expected DT was obtained when the combination of crosscarmellose sodium and crosspovidone (XL-10) were used. Similarly, the other formulation was prepared by using lower concentration of sodium starch glycolate, the DT was found to be higher, but by increasing the concentration of sodium starch glycolate, expected DT was obtained with optimum tablet characteristic.
- 44 - P a g e International Standard Serial Number (ISSN): 2319-8141 The powder parameters like bulk density, bulkiness, carr s index and Hauser ratio were carried out for all 9 formulations of the powder blend ready for compression. The values are found to be, Bulk density 0.5081-0.5319, tapped density 0.5814-0, Carr s index: 14.03-19.13, Hauser s ratio: 1.1325-1.1666, Angle of repose: 16-34. The post compressional parameters reveals that Weight variation was between: 97.88-103.04mg, Thickness was varied: 2.62-2.70, Hardness was between: 2.5-4.0 all the parameters meets the acceptable limits. Disintegration time (in seconds) for all the formulation batches was evaluated.based on the study it was found that formulation F. No 4 and F. No 8 exhibited a disintegration time (in seconds) more than 100 seconds, which may be due to the presence of dextrose as diluent, though it may contain different types of disintegrating agents. If lactose is used as diluent and containing a combination of disintegrating agent such as croscarmellose sodium and crospovidone XL-10, the DT was slightly higher when compared to that of formulation B. No 5, which contained sodium starch glycolate as disintegrating agent at a concentration of 3%. The formulation B. No 3 and B. No 5 showed a low DT value among the all formulation prepared which may be due to the presence of appropriate concentration of sodium starch glycolate as disintegrating agent. Finally it may be concluded that sodium starch glycolate at concentration of 3% with either lactose or mannitol may be considered as best diluents. Similarly results to those for DT were found to be significant for wetting time. Thus it may be concluded that formulation B. No 3.6 and 7 showed low wetting time values. Formulations Batch no 03 and 05, showed rapid dissolution rate, the percentage cumulative drug release () after 5 minutes found to be more than 80% and complete dissolution was achieved within 15minutes. Thus it may be concluded that formulation B. no 3 may be considered as best formulation with respect to in vitro drug release profile. Based on pre-compression parameters formulation No 3 was considered as best formulations. With respect to post-compression parameters like disintegration time, wetting time and dissolution study (in vitro) formulation No 3, 5, 6 and 7 were considered as best formulation. The release kinetics reveals that the drug release followed the I st order release kinetics with diffusion mechanism. In present study short term physical stability and drug content and dissolution profile were carried out of formulation batch no 03, and 06. The results of drug content in all the formulations inferred no significant deviation from the initial values this indicates the stability of drug in all the batches of tablets. CONCLUSION: The sublingual tablets of F 3 was contain 10mg of Oxazepam 28mg of MCC PH 200 and 58.6mg of mannitol (DC) and sodium starch glycolate 3mg, talc 0.2mg and flavor orange 0.2mg considered to be the best among all other nine formulations of tablets since it exhibited a good dissolution profile,
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