Recent years, many scientists attempt to use polymers as materials for instead of gelatin to prepare capsules. The non-gelatin capsules showed more stable were than gelatin capsules and accept for vegetarians. In this study, hard capsule shells were made by a heat-melting method, which involved heating Polyethylene oxide (PEO) or Hydroxypropyl cellulose (HPC) powder into a mold, followed by inserting a suitable size of pestle in a mold to coat the melted shell materials (HPC or PEO) onto the pestle, and formed the capsule shells. The water uptake and dissolution test of various non-gelatin capsule shells were evaluated in either simulated gastric fluid or intestinal fluid buffer media that added one of inorganic salts including lithium chloride, sodium chloride, potassium chloride, calcium chloride or aluminum chloride. Propranolol hydrochloride and theophylline were selected as the model drugs for drug release studies. It was found Propranolol hydrochloride released from various capsules was faster than that of theophylline due to the higher solubility of the former. There were no significantly different in the release rate from the formulation containing either microcrystalline cellulose or lactose as diluents. Moreover, release rate was decreased with increasing molecular weight grades of HPC used as shell materials. Inorganic salt showed having marked influence on the dissolution rate, and that decreased with increasing concentration of salt in dissolution medium. The drug release from HPC capsules was greater affected by electrolytes than that from gelatin and PEO capsules. In vivo studies were conducted in rabbits with novel capsules and compared with gelatin capsules. It was found that the pharmacokinetic parameters included AUC0-∞ and T1/2 has showed no significantly difference among various capsules, all containing theophylline formulation. The correlation between TD50 in vitro and several parameters in vivo were established. HPMC capsule were also prepared, and its in vivo-in vitro test shows no significantly difference from the gelatin capsule.
