Evaluation, Formulation and Optimization Study of Myrrh (Commiphora myrrha) Resin as Rate Controlling Excipient in Sustained Release Matrix Tablets of Theophylline

Aims: To investigate myrrh (Commiphora myrrha) resin as a rate controlling excipient in sustained release matrix tablets of theophylline, and to optimize formulation and process variables of the tablet preparation using central composite design.

Methodology: Wet granulation was employed for preparation of theophylline sustained release matrix tablets. Central composite design was used as an optimization tool having a total of 13 experimental runs with 5 central points. The myrrh resin amount (A) and compression force (B) were selected as independent variables. Cumulative % release of drug at 1 h, and 12 h and time to 50% drug release were taken as dependent variables.

Results: The moisture content and total ash values of myrrh resin were found to be 4.67±0.58% and 0.24±0.05%, respectively. The angle of repose for all formulated granules were less than 30°. The hardness of different formulations were found to be between 89.8±2.86 and 133.7±3.53 N while all tablets have passed the friability test (<1%). Analysis of dissolution data of the formulations indicated that the best fitting model was the first order kinetics whereas the mechanism of drug release pattern followed anomalous or non-fickian diffusion. An optimum region of 24.98%, 91.22% and 2.86 h was obtained for cumulative % release of drug at 1 h, 12 h, and time to 50% drug release, respectively when 17.5% myrrh resin amount and 13.9 KN compression force was used. For the optimized formulation, the experimental values were found to be in close agreement with the predicted values (relative errors ranged between -4.496 and 4.814%) confirming the predictability and validity of the model.

Conclusion: The results of this study showed that the myrrh resin from Commiphora myrrha can be used as a potential alternative rate controlling excipient for sustained release matrix tablet formulation.