European Journal of Biomedical and Pharmaceutical Sciences

A NEW TREND IN THE FORMULATION OF THE SOLID DOSAGE FORM TO INCREASE CANDESARTAN CILEXETIL SOLUBILITY IN A SIMULATION MEDIA TO GASTROINTESTINAL TRACT

Omar Y. Mady, El-Zeiny M. Ebeid, Ahmed A. Donia, Waseem Qasim*

ABSTRACT

The pharmaceutical active substance solubility is the rate-limiting step for classes II and IV drugs. In pharmaceutical industry, the additives used to improve the manufacture process and passing the pharmacopeial standards. In this study, dual aims for the additives were tested, to comply the product with the pharmacopeial standards of the prepared pharmaceutical dosage form and to enhance the drug solubility. Solubility of candesartan cilexetil (CC) in a physical mixture with either polyvinyl pyrrolidone (PVP) or polyethylene glycol (PEG) in simulation conditions to GIT was tested. Then, tablet formulations based on the solubility data pressed and then characterizations of the prepared tablets in comparing with the drug brand name were carried out. Both polymers enhanced the drug solubility. PVP is protonated in acid medium forming complex with the acid form of the drug and non-protonated in phosphate buffer interacting with the drug basic form. The free energy changes associated with increasing solubility indicating that the process is spontaneous by addition of the polymer. Increasing the polarity of PVP in acid medium led to decreasing its randomization because of the nature of the interaction with drug. In phosphate buffer the nature of interaction changed which led to more randomization process. The values of enthalpy changes are positive indicating that the solubilizing effect of the polymers on the drug is endothermic. The enthalpy changes on using PEG is due to its weak polar center, which is influenced by the polymer molecular weight, solution pH and temperature. Candesartan tablets prepared according to the solubility findings and drug release showed improvement comparing with the brand name. Accelerated stability study showed the shelf life of the formula is two years which could be also increase by using increasing the additives percent. This work is a preformulation step carried out in each R&D departments of research centers or pharmaceutical industries. The results showed that it could be decreasing the dose of the drug by using additives in a physical mixture form. This leads to decreasing the drug dose and consequently the cost and its side effects without any additive technological aspect.

Keywords: Candesartan cilexetil, PVP, PEG, physical mixture, solubility, solubility thermodynamics, tableting.