DESIGN AND EVALUATION OF MODIFIED PULSINCAP OF TRAMADOL HCL ACCORDING TO CIRCADIAN RHYTHM

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1 DESIGN AND EVALUATION OF MODIFIED PULSINCAP OF TRAMADOL HCL ACCORDING TO CIRCADIAN RHYTHM Priyanka Modi*, Ghanshyam Patel, Dr. Ragin Shah, Arihant School of pharmacy and bio- research institute, Gandhinagar, Gujarat ABSTARCT The objective was to design and evaluate modified pulsincap of Tramadol HCl according to circadian rhythm using formaldehyde vapour for cross-linking to make capsule body water insoluble and hydro gel plug to achieve a predetermined lag time for chronotherapy of rheumatoid arthritis. The capsule body was made water insoluble by exposing the body to formaldehyde vapour. A physical mixture of drug and excipients was filled in the treated capsule body and hydro gel plug was fitted to the mouth of the treated body and the untreated cap was fitted to the treated body which was coated with Eudragit S-100 to prevent variable gastric emptying. Developed formulation was evaluated for in-vitro drug release in ph 1.2 (2 hrs), phosphate buffer ph 6.8 (3 hrs) and phosphate buffer ph full factorial design was used for optimization. Formulation F1 and F5 both showed predetermined lag time of 6 hrs but in formulation F1 less amount of SSG and HPMC K 4 M was used so it was selected as optimized formulation showing the immediate release of the drug after the lag time of about 6 hrs. Key words: modified pulsincap, chronotherapy, rheumatoid arthritis INTRODUCTION A major objective of chronotherapy in the treatment of several diseases is to deliver the drug in higher concentrations during the time of greatest need according to the circadian onset of the disease or syndrome. To follow this principle one must have to design the dosage forms so that it can be given at the convenient time for example bed time for the diseases with the drug release in the morning. Pulsincap is the one of the approaches for pulsatile drug delivery. Pulsincap system comprises of a water-insoluble capsule body, soluble cap and hydro gel plug. When this capsule came in contact with the dissolution fluid, it dissolves and after a lag time, the plug pushed itself outside the capsule and rapidly releases the drug. The length of the plug and its point of insertion into the capsule controlled the lag time. Pulsincap was studied in human volunteers and was reported to be well tolerated. [1-3] Almost 20% people of the total population of the world suffering from arthritis. Rheumatoid arthritis is a generic term that describes many different *Corresponding Author Priyanka Modi 1 P a g e

2 and usually painful conditions. It is based on the circadian rhythm of the body because peak pain occurs in early morning and decreases as the time passes. These will be possible by formulating pulsatile delivery of drug, which release the drug rapidly in early morning followed by predetermined lag time and thus prevent unusual exposure of drug to the patient. [4-6] Tramadol hydrochloride is a synthetic analgesic with half life of 5-6 hrs and has a modest affinity for the µ receptor. Its additional effect on the descending inhibitory pathways relies on inhibition of serotonin and norepinephrine re-uptake. Thus it gives dual mode of analgesic action. It doesn t only provide analgesia over a wide range of pathologies but it has significant advantages like no respiratory depression or cardiac side effects. It is the BCS class-i drug having good absorption throughout the GIT. The most common side effects of Tramadol HCl are nausea and vomiting which can be prevented by pulsatile delivery. Hence it best suits for this approach. [7] The capsule bodies of size 1 were treated with formaldehyde vapor to make capsule body water insoluble. The amino group in the gelatin molecular chain could react with an aldehyde group of formaldehyde by a schiff s base condensation reaction to produce a water insoluble body. The concentrations of formaldehyde solution and exposure time to capsule bodies were optimized by solubility study of treated capsule bodies. [8-10] The physical mixture of drug and excipients was filled in formaldehyde treated capsule body and fitted with hydro gel plug which was compressed having diameter of 6 mm. Then untreated cap was fitted on the body and the entire capsule device was coated with Eudragit S-100. After the cap opening in the dissolution media, the hydrogel plug came into contact with dissolution media and it hydrated and started to swell and after ejection of plug from the body, the drug was released immediately. In this study an attempt had been made to develop modified capsule which will give pulsatile release of Tramadol HCl for arthritic pain. MATERIAL AND METHODS Materials Tramadol HCl was obtained from Apex pharma, Hyderabad. Sodium starch glycolate, HPMC K 4 M, Na-alginate, Eudragit S-100, Acetone were from S.D Fine chemicals, Mumbai. Formaldehyde, Sodium chloride, Potassium permanganate was from Dow chemical s Rajkot. All other ingredients used were either pharmaceutical or analytical grade. Methods Formaldehyde treatment and its optimization Formalin treatment has been employed to modify the solubility of gelatin capsules. [8-11] Hard gelatine capsule of size 1 and 50 in number taken. Their bodies were separated from the caps. 25 ml of 5%, 7%, 10% (v/v) formaldehyde was taken into separate desiccators and a pinch of potassium permanganate was added to it respectively, to generate formalin vapours. The wire mesh containing the empty bodies of capsule was then exposed to 2 P a g e

3 formaldehyde vapours. The caps were not exposed leaving them water-soluble. The desiccators were tightly closed. The reaction time was optimized by removing capsule bodies at different time intervals and dried at 50 C for 30 min to ensure completion of reaction between gelatin and formaldehyde vapors. The bodies were then dried at room temperature to facilitate removal of residual formaldehyde. These capsule bodies were capped with untreated caps and stored in a polythene bag. Tests for Formaldehyde Treated Empty Capsules Various physical and chemical tests were carried out simultaneously for formaldehyde treated and untreated capsules. a) Physical tests Identification attributes: The size 1 capsule were one with a red cap and white colored body. They were lockable type, odourless, softy and sticky when treated with wet fingers. After formaldehyde treatment, there were no significant changes in the capsules. They were non-tacky when touched with wet fingers. Visual defect: In about 50 capsule bodies treated with formaldehyde, about five were found to be shrunk or distorted. Dimensions: Variations in dimensions between formaldehyde, treated and untreated capsules were studied. The length and diameter of the capsules were measured before and after formaldehyde treatment, using dial caliper. b) Chemical test Qualitative test for free formaldehyde Standard formaldehyde solution used is formaldehyde solution (0.002 w/v) and sample solution is formaldehyde treated bodies (about 25 in number) were cut into small pieces and taken into a beaker containing distilled water. This was stirred for 1 hrs with a magnetic stirrer, to solubilise the free formaldehyde. The solution was then filtered into a 50 ml volumetric flask, washed with distilled water and volume was made up to 50 ml with the washings. 1ml of sample solution, 9 ml of water was added. One ml of resulting solution was taken into a test tube and mixed with 4 ml of water and 5 ml of acetone reagent. The test tube was warmed in a water bath at 40 o C and allowed to stand for 40 min. The solution was not more intensely colored than a reference solution prepared at the same time and in the same manner using 1ml of standard solution in place of the sample solution. The comparison should be made by examining tubes down their vertical axis. Drug-excipient compatibility study FTIR absorption spectra of pure drug, physical mixture and pulsincap formulation were recorded in the range of 400 to 4000 cm -1 by KBr disc method using FTIR spectrophotometer. Selection of core physical mixture and hydrogel plug In the present study for the preparation of modified pulsincap the composition of physical mixture and the type of hydrogel plug. Here the effect of osmogen (NaCl) and superdisintegrant (SSG) in core 3 P a g e

4 physical mixture was checked on the immediate drug release after the lag time. Hydrogel plug of two polymers HPMC K 4 M and Na-alginate were selected. Both are swellable hydrophilic polymers and control the lag time. Eudragit S-100 was selected for enteric coating of entire capsule device. 5% w/v solution of Eudragit S-100 in acetone was selected for enteric coating which was suitable for uniform dip coating. Preliminary trial formulations of modified pulsincap Table 1: Composition of preliminary formulation Ingredients (mg) P1 P2 P3 P4 P5 P6 Tramadol HCl MCC NaCl SSG HPMC K4M plug Na-alginate plug Total weight* (mg) ± ± ±6.9 *Values are mean± S.D, n=10 Wt. of empty capsule =78 mg, Avg. wt gain by 5% Eudragit S-100 coating solution= 7.53% Evaluation of modified pulsincap Lag time [12] Lag time is the total time period after which the plug is ejected out of the capsule body and the drug releases immediately. Lag time was determined visually using phosphate buffer ph 6.8 and 7.4. For lag time determinations USP paddle apparatus was used. Capsules were tied with the paddle by cotton thread; temperature was maintained at 37 C at 50 rpm. Results of preliminary trial formulations are depicated in Table 9. In-vitro release profile [9, 13] Dissolution studies were carried out by using USP XXIII dissolution test apparatus ± ± ±6.5 (Basket) method. Capsules were placed in a basket so that the capsule should be immersed completely in dissolution media but not float. In order to simulate the ph changes along the GI tract, three dissolution media with ph 1.2, 6.8 and 7.4 were sequentially used referred to as sequential ph change method. When performing experiments, the ph 1.2 medium (0.1 N HCl) was first used for 2 hrs (since the average gastric emptying time is 2 hrs) then removed and the fresh ph 6.8 phosphate buffer was added. After 3 hrs (average small intestinal transit time is 3 hrs) the medium was removed and fresh ph 7.4 dissolution medium was added for subsequent hrs. 900ml of the dissolution medium was used at each time. 4 P a g e

5 Rotation speed was 100 rpm and temperature was maintained at 37±0.5 C. 5 ml of dissolution media was withdrawn at predetermined time intervals and fresh dissolution media was replaced. The withdrawn samples were analyzed at 270 nm, by UV absorption spectroscopy. Results of drug release study are shown in Figure 4. Optimization of variables using 3 2 full [9, 14, 15] factorial design A full factorial 3 2 design is used for optimization procedure. It is suitable for investigating the quadratic response surfaces and for constructing a secondorder polynomial model, thus enabling optimization of the modified pulsincap. Table 2 summarizes the independent along with their levels. The resulted formulations are listed in Table 3. A statistical model incorporating interactive and polynomial term will be used to evaluate the response. Y = β0 + β1x1+ β2x2 + β12x1x2 + β11x1 2 + β22x2 2 Where, Y is the dependent variables. Table 2: Coding of variable Coded values Actual values X1(conc. ratio of SSG and NaCl) X2 ( wt. of hydrogel plug in mg) -1 10: : :70 60 Dependent variables is Y = Lag time Table 3: Compositions of factorial formulations Ingredients (mg) F1 F2 F3 F4 F5 F6 F7 F8 F9 Tramadol HCl MCC NaCl SSG HPMC K4M plug Total weight* (mg) ± ± ± ± ± 5.7 *Values are mean ± S.D where, n=10 Avg. wt gain by 5% Eudragit S-100 coating solution= 8.23 % ± ± ± ± P a g e

6 Statistical analysis of the data Statistical analysis of the factorial design formulations was performed by multiple regression analysis using Microsoft Excel D response plots were constructed using Design expert 8.0 trial version software Result and Discussion Optimization of formaldehyde concentration & exposure time for crosslinking Table 4: Solubility study of cross-linked capsule bodies The solubility of the capsule bodies checked and it was found that 10% v/v formaldehyde solution and 6 hrs exposure times was optimum in which capsule bodies remained intact up to 12 hrs in all the media (Table 4). So it was used in cross-linking of capsule bodies. After formaldehyde treatment of 100 capsule bodies about 10 were found to be distorted. Then they were subjected to measurement of dimensions as shown in Table 5. Formaldehyd e conc. (%v/v) Time of exposur e (hrs) Observation in dissolution media 0.1 N HCl Phosphate buffer 6.8 Phosphate buffer % 2 softened in 1 hr softened in 1 hr softened in 1 hr 4 softened in 2 hrs softened in 2 hrs softened in 2 hrs 6 softened in 4 hrs softened in 4 hrs softened in 4 hrs 7% 2 softened in 3 hrs softened in 3 hrs softened in 3 hrs 4 softened in 5 hrs softened in 5 hrs softened in 5 hrs 6 softened in 7 hrs softened in 7 hrs softened in 7 hrs 10% 2 softened in 9 hrs softened in 9 hrs softened in 9 hrs 4 Intact up to 10 hrs Intact up to10 hrs Intact up to10 hrs 6 Intact up to 12 hrs Intact up to12 hrs Intact up to 12 hrs Table 5: Comparison of dimension of capsule bodies Parameter Before treatment After treatment Avg. capsule length (mm) Avg. diameter of capsule body (mm) Avg. length of capsule body (mm) From the observations of the cross linked capsule bodies it was found that there was slight decrease in the diameter and length after formaldehyde treatment. 6 P a g e

7 Qualitative test for free formaldehyde The formaldehyde capsules were tested for the presence of free formaldehyde. The sample solution was not more intensely colored than the standard solution inferring that less than 20 µg free formaldehyde is present in 25 capsules. Drug- excipient compatibility study FTIR spectrum of Tramadol HCl, physical mixture and pulsincap formulation are shown in Figure 1, 2 and 3 respectively. From the FTIR spectra of physical mixture and pulsincap formulation, it was found that drug and excipients are compatible with each other. Figure 1: FTIR spectra of Tramadol HCl Figure 2: FTIR spectra of physical mixture of Drug and excipients 7 P a g e

8 Figure 3: FTIR spectra of pulsincap formulation Evaluation of hydrogel plug Table 6: Evaluation of Hydrogel plug of trial formulations Type of plug Thickness (mm) Friability (%) Swelling index (%) ( in 6 hrs) ph 6.8 ph 7.4 HPMC K 4 M 2.40 ± ± ±1.5 Na-Alginate 2.42 ± ± ± 1.7 values are mean± S.D, n=3 The swelling index of Na-alginate was found to be more in comparison with the HPMC K4M plug at the end of 6 hrs. Evaluation of modified pulsincap formulations Lag time Table 7: Lag time of preliminary trial formulations Batch Lag time (min.) P1 460 ± 12 P2 447 ± 15 P3 365 ± 10 P4 416 ± 10 P5 405 ± 16 P6 320 ± 13 Values are mean ± S.D, n=3 Due to enteric coating by Eudragit S-100 pulsincap remained intact in 0.1N HCl But starts to dissolve in phosphate buffer. It was postulated that after the dissolution of coating the cap starts to dissolve and fluid enters the body because it was insoluble 8 P a g e

9 % cumulative drug release INTERNATIONAL JOURNAL OF but permeable. After entering the body the osmogen and superdisintegrant creates the pressure on swollen plug and hence plug ejected out of the body. From the results of lag time of preliminary trial formulations, it was found that there is no significant In vitro drug release study effect of osmogen (NaCl) alone on the lag time but in combination with the superdisintegrant (SSG) it helps in ejection of plug after lag time and releases the drug immediately Time (hrs) P1 P2 P3 P4 P5 P6 Figure 4: In-vitro drug release study of preliminary formulations From the drug release study it was also found that sustaining capacity of HPMC K 4 M plug is more than the Na-alginate plug. From the result of lag time it was observed that the P1-P6 had the lag time in the range of 5-8 hrs. P3 formulation had Evaluation of modified factorial formulations Lag time Table 8: Lag time of factorial formulations the lag time of about 6 hrs having the ratio of NaCl to SSG was 80:20 (40 mg NaCl and 10 mg SSG) and the HPMC K 4 M plug of 50 mg weight. Hence it was used for the setting of levels and factors for the 3 2 full factorial designs. Batch Lag time (min) F1 365 ± 09 F2 315 ± 11 F3 275 ± 10 F4 405 ± 15 F5 363 ± 13 F6 320 ± 10 F7 425 ± 12 F8 409 ± 14 F9 393 ± 10 Values are mean ± S.D, n=3 9 P a g e

10 %cumulative drug release study INTERNATIONAL JOURNAL OF From the lag time determination study of the factorial formulations, it was found that as the weight of the hydrogel plug increases the lag time also increases and as the amount of super disintegrant increases the lag time decreases. From all the formulations F1 and F5 shows the lag time of about 6 hrs. In vitro drug release study of factorial formulations Time 4 (hrs) F1 F2 F3 F4 F5 F6 F7 F8 F9 Figure 5: In-vitro drug release study of factorial formulations Pulsincap formulation of F1-F9 showed distinct lag time as given in Figure 5. It showed that lag time increases with increase in weight of hydrogel plug and decreases with increase in ratio of SSG and NaCl. Upon contact with dissolution media the hydro gel plug starts to swell and due to pressure inside the capsule body plug comes out. So both the parameters affect the lag time and drug release from the pulsincaps. Formulations F1 (SSG to NaCl ratio 20:80 and HPMC K 4 M plug of 40 mg) and F5 (SSG to NaCl ratio 10:90 and HPMC K 4 M plug of 50 mg) provides the desired lag time of about 6 hrs. Statistical analysis of the data The fitted full model equation relating the response Y (lag time) to the transformed factor are shown in following equation. Y= 362 (35X 1 ) + (44.83X 2 ) + (13.75X 1 X 2 ) + (1X 1 2 ) + (0.5X 2 2 ) The P value for X 1, X 2 and X 1 X 2 was found to be , and respectively which is less than Thus X 1, X 2 and X 1 X 2 has significant effect on the dependent variable Y (Lag time) while other term X 1 2 and X 2 2 were rendered insignificant having P value greater than P a g e

11 Table 9: Regression Statistics for Y (Lag time) Regression Statistics for Y Multiple R R Square Adjusted R Square Standard Error Observations 9 Coefficients P- value β0 = E-06 β1 = β2 = β12 = Β11 = Β22 = Table 9 shows the results of the analysis of variance (ANOVA), which was performed to identify insignificant factors. The high values of correlation coefficient for lag time indicate a good fit, i.e., good agreement between the dependent and independent variables. The significance test for regression coefficients was performed by applying the student F test. (Table 10) Positive value of coefficient of X 1 indicates that dependent variable (lag time) is directly proportional to the X 1 variable (weight of plug) and negative value of coefficient of X 2 indicates that if there is increase in X 2 variable (ratio SSG:NaCl), there is decrease in lag time Table 10: Testing the model in portions Regression Lag time (Y) DF SS MS F R 2 FM RM Error FM F cal = F cri = RM DF = (2,3) DF: degree of freedom, SS: sum of squares, MS: mean of squares, F: Fischer s ratio, R2: regression coefficient, FM: full model, RM: reduced model. 11 P a g e

12 So, the reduced model equation is as follows: Y= 362 (35X 1 ) + (44.83X 2 ) + (13.75X 1 X 2 ) The results for testing the model in portions are shown in Table Since the calculated value (F = ) is less than critical value, it may be concluded that the quadratic terms β11 and β22 do not contribute significantly to the prediction of lag time and therefore can be omitted from the full model. Figure 6: Contour plot showing relationship between two independent variables on lag time Figure 7: Response surface plot showing the influence of independent variables on lag time. 12 P a g e

13 Figure 6 and 7 showed the countor plot and response surface plot of ratio of SSG to NaCl (X 1 ) and plug weight (X 2 ) versus lag time respectively. It was also observed that the X 1 and X 2 appear to favor the preparation of modified pulsincap of Tramadol HCl. It can say that the lag time and drug release profile may be changed by appropriate selection of the X 1 and X 2 levels. The area in contour plot (Figure 5.12) shows if we selected X1 and X2 in this range we get the desired release profile of Tramadol HCl modified pulsincap. CONCLUSION Tramadol HCl was successfully formulated as a modified pulsincap to deliver drug after predetermine lag time of 6 hrs. Formulation F1 and F5 both gave the lag time of about 6 hrs but the F1 ( Ratio SSG to NaCl 10:90 and plug weight 40 mg) was selected as optimized formulation hence less amount of SSG and HPMC K 4 M were used in that in comparison with F % drug was released in 1 hr after the lag time in optimized formulation which is necessary in pulsatile release. REFERENCES 1. Suresh S, Pathak S. Chronopharmaceutics: Emerging role of bio-rhythms in optimizing drug therapy. Indian J Pharm Sci 2005; 67: Kuotsu K, Behra M. Drug delivery system based on chronobiology-a review. Journal of controlled release 2010; 147: Garg T, Chanana A. Pulsatile drug delivery system - Pulsincap system. IOSR Journal of Pharmacy 2012; 2: Singh R, Sharma P. Circadian rhythm in arthritis: A review. Journal of Chronotherapy and Drug Delivery 2011; 1: Agarwal V, Sharma P. Chronobiological approach for treatment of rheumatoid arthritis. Journal of Chronotherapy and Drug Delivery 2011; 2: Gandhi B, Mundada A. Chronopharmaceutics: As a clinically relevant drug delivery system Drug delivery 2011; 18: Stephan A. The role of Tramadol in current treatment strategies for musculoskeletal pain Therapeutics and Clinical Risk Management 2007; 3: Sharma G, Srikanth M. Application of modified pulsincap technique for oral controlled drug delivery of Gliclazide. Int J Pharm Pharm Sci 2012; 4: Patel D, Jani R. Design and Evaluation of colon targeted modified pulsincap delivery of 5- Fluorouracil according to circadian rhythm. International Journal of Pharmaceutical Investigation 2011; 1: Gohel M, Manhapra S. Modulation of active pharmaceutical material release from a novel tablet in 13 P a g e

14 capsule system containing an effervescent blend. Journal of Controlled Release 2002; 79: Lachman L, Leiberman H and Kanig J, 3rd Edn, The Theory and practice of Industrial Pharmacy, Varghese publishing house, Bombay. pp T. Bussemer, N.A. Peppas, R. Bodmeier. Evaluation of the swelling, hydration and rupturing properties of the swelling layer of a rupturable pulsatile drug delivery system. European journal of pharmaceutics and biopharmaceutics 2003; 56: Abraham S, Srinath M. Development of modified pulsincap drug delivery system of Metronidazole for drug targeting. Indian J Pharm Sci 2007; 69: Patel B, Patel C. Formulation and evaluation of metoprolol succinate er and atorvastatin calcium ir using natural gum Research journal of pharmaceutical, biological and chemical sciences 2011; 4: Patel D, Patel M. Optimization of fast dissolving tablets of etoricoxib prepared by sublimation technique. Indian journal of pharmaceutical sciences 2008; P a g e