Formulation development and optimization of Lamivudine 300 mg and Tenofovir Disoproxil Fumarate (TDF) 300 mg FDC tablets by D-optimal mixture design

The usage of fixed dose combination (FDC) tablets of Lamivudine and Tenofovir Disoproxil Fumarate (TDF) is increasing due to increased incidences of HIV/Hepatitis B and HIV/TB co-infections. This is likely to increase the financial crisis due to limited resources for funding procurement of ready-made products from the pharmaceuticals manufacturing leading countries. Therefore, production of local oral tablets containing Lamivudine and TDF FDC is inevitable. Lamivudine 300 mg/TDF 300 mg tablets were developed and optimized by D-optimal mixture design and produced by direct compression technique. Twenty trial formulations with independent variables, including PVP-CL 1-12.00%, PVP-K30 1-10.00%, starch-1500 2.5-12.5% and Avicel-PH102 2-19.25% were prepared by direct compression technique. The formulations were assessed on assay, dissolution, friability, weight variation and disintegration time. It was found that assay ranged from 98.13-101.95% for Lamivudine, 98.25-102.84 for TDF, both were within the in-house assay specification of 95 to 105%. Dissolution at single point was above 80% for Lamivudine 93.96-100.55% and 95.85-103.15% for TDF, disintegration time was between 1.92-66.33 min and friability 0.06-12.56%. Out of twenty formulation trials, eight formulations had all parameters in proven acceptable range. On optimization, one formulation with independent variables, PVP-CL 5.67%, PVP-K30 1.00%, Starch-1500 5.76% was selected. The optimized formulation was comparable to the reference product on the market with similarity factor (f2) and difference factor (f1) within the acceptable range for both Lamivudine and TDF.