Coprocessing of nevirapine and stavudine by spray drying.

The objective of the present study was to coprocess 2 active pharmaceutical ingredients (APIs), nevirapine (NVP) and stavudine (STV), by spray drying technique to overcome the respective problems of poor solubility and poor content uniformity. The coprocessed product (NVP-STV CP) and untreated APIs were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), particle size, surface area analysis, compressibility, and solubility. Coprocessing enhanced NVP solubility by approximately 1.5 fold and provided uniform distribution of low-dose STV in the formulation composite. Phase solubility studies elucidated the mechanism of enhanced NVP solubility. The coprocessed product was stable under accelerated stability conditions of 40 degrees C/75% relative humidity (RH) for 3 months. The coprocessed product was formulated into 3 drug fixed dose combination (FDC) tablets with lamivudine (LMV), which gave an enhanced in vitro NVP drug release compared with the control formulation. Spray drying as a coprocessing technique optimally utilized the individual components of the antiretroviral FDC tablets and synergistically enhanced the performance attributes.