Abstract

Tramadol hydrochloride is an opiate analgesic used to treat mild to moderate pain. The present study aimed to optimize and evaluate the formulation of tramadol hydrochloride as a sustained release tablet using a hydrophilic and a hydrophobic polymer, i.e., hydroxypropyl methylcellulose K100M and glyceryl behenate, respectively. A central composite experimental design with 2 factors at 3 levels each was used to evaluate the effects of the critical variables, i.e., concentration of hydroxypropyl methylcellulose K100M and glyceryl behenate, on the drug release properties of the formulated tablets. The responses (dependent variables) studied for this investigation were release after 12 h (T₁₂), time to 100 % release (T₁₀₀) and R² of Higuchi equation. Response surface analysis clearly showed the positive effect of the polymers on T₁₂, T₁₀₀ and R². The tablets were evaluated for thickness, weight variation test, drug content, hardness, friability and in vitro release. All tablet formulations exhibited acceptable pharmacotechnical properties and met in-house specifications for the tested parameters. The optimized formulation showed drug release of >12 h. The statistically optimized formulation showed acceptable stability performed according to the guidelines of international council for harmonisation. The result of the study suggests that the mixed matrix of hydroxypropyl methylcellulose and glyceryl behenate can be used as a release retarder for the formulation of Tramadol hydrochloride, a drug with good water solubility.