Development and evaluation of microporous osmotic tablets of diltiazem hydrochloride

Development and pharmacokinetic evaluation of osmotically controlled drug delivery system of Valganciclovir HCl for potential application in the treatment of CMV retinitis

Valganciclovir HCl (VGH) is the widely used drug for the treatment of cytomegalovirus (CMV) retinitis infection with an induction dose of 900 mg per oral (p.o.) twice a day and a maintenance dose of 900 mg (p.o.). This required dose of the drug also leads to multiple side effects due to repeated administration. The research was highlighted to develop, formulate, optimize, and evaluate single-core osmotic pump (SCOP) tablet of VGH with the dose of 450 mg to reduce dosing frequency and associated side effects. The decrease in dose also minimizes the hepatic and nephrotic load. The optimized batch of the formulation was subjected to comparative in vitro and in vivo evaluation. The tablet core composition is the primary influencer of the drug delivery fraction in a zero order, whereas the membrane characteristics control the drug release rate. In vivo pharmacokinetic studies revealed that the newly developed osmotic formulation has controlled zero-order release for 24 h with a single dose of 450 mg while the marketed formulation requires twice administration within 24 h to maintain the plasma concentration in the therapeutic window. The pharmacokinetic study demonstrated that the developed formulation has the area under curve (AUC) of 58.415 µg h/ml with single dose while the marketed formulation shows the AUC of about 37.903 µg h/ml and 31.983 µg h/ml for first and second dose, respectively. The large AUC demonstrates the extended release of drug with a single dose and effective plasma concentration. Hence, the developed formulation can be a promising option for the treatment of CMV retinitis with the minimum dose and dosing frequency.

Design and development of controlled porosity osmotic tablet of diltiazem hydrochloride

The present work aims towards the design and development of extended release formulation of freely water-soluble drug diltiazem hydrochloride (DLTZ) based on osmotic technology by using controlled porosity approach. DLTZ is an ideal candidate for a zero-order drug delivery system because it is freely water-soluble and has a short half-life (2-3 h). Sodium chloride (Osmogen) was added to the core tablet to alter the solubility of DLTZ in an aqueous medium. Cellulose acetate (CA) and sorbitol were used as semipermeable membrane and pore former, respectively. The effect of different formulation variables namely concentration of osmogen in the core tablet, % pore former, % weight gain, pH of the dissolution medium and agitation intensity on the in vitro release was studied. DLTZ release was directly proportional to % pore former and inversely proportional to % weight gain. The optimized formulation (F8) delivered DLTZ independent of pH and agitation intensity for 12 h at the upper level concentration of % pore former (25% w/w) and middle level concentration of % weight gain (6% w/w). The comparative study of elementary osmotic pump (EOP) and controlled porosity osmotic pump revealed that it superior than conventional EOP and also easier and cost effective to formulate.