Abstract

The objectives of the present study were to formulate sustained release pyridoxine hydrochloride capsules and to study the effect of propylene glycol co-solvents on the in vitroproperties of the capsules. All batches of formulations were made with fixed concentrations of binder-disintegrants, diluents and equal load of active pharmaceutical ingredient. The granules were prepared by wet granulation using propylene glycol water co-solvent as the wetting agent, sodium carboxymethylcellulose (SCMC) and maize starch were used as binder-disintegrant and kaolin was used as the diluents. The micromeritic properties of the granules were analysed by direct and indirect methods. The granules were encapsulated in hard gelatin capsule No. 1. The capsule weight uniformity, disintegration time and drug content were determined. In vitro dissolution test was performed in 0.1 N HCl, simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.2). The results showed that the particles size of granules ranged from 245 to 259 µm and had good flowability. The capsules complied with British Pharmacopoeia (BP) requirement for capsule weight uniformity. The drug content was within 90 to 110% of the average values.  The results of in vitro drug release in SGF (pH, 1.2) showed that the release of pyridoxine hydrochloride was very slow and was significantly (P < 0.05) lower than the release in 0.1 N HCl and in SIF (pH, 7.2), respectively. Therefore, pyridoxine hydrochloride sustained release capsules could be formulated with kaolin as the diluent and propylene glycol co-solvent as the moistening agent in order to reduce the frequency of administration of this drug and improve patient compliance.

Key words: Pyridoxine hydrochloride, sustained release, capsules, particle size analysis.