Abstract

STUDIES ON THE PHYSICOCHEMICAL PROPERTIES AND RELEASE PROFILES OF TABLET/CAPSULE FORMULATIONS OF VERNONIA AMYGDALINA DRY LEAF EXTRACT FOR THE MANAGEMENT OF DIABETES.

*Obarisiagbon Aiwaguore Johnbull, Okor Rolly Sidney and Uhumwangho Michael

ABSTRACT

Many products of herbal origin in use in most countries today may be causing numerous untold hardships to their users. There is need therefore to standardize the dose of these products to ensure accurate, effective and safe use with Vernonia amygdalina leaf extract as case study. The fresh leaves of Vernonia amygdalina were sorted, washed, dried, pulverized and extracted with methanol as solvent. The powdered extract was characterized to determine some of the micromeritics properties. Allometric conversion of doses to obtain Human Equivalent Dose (HED) was employed to get 500 mg dose of VA tablet/capsule to be taken two times daily. Carnauba wax and Eudragit® L100 at concentration (0.25 – 2.0 %w/w) per tablet/capsule were used as binders by melt and polymeric granulations respectively. The granules were compressed into tablets at an arbitrary load scale of 4 units; while the granules were weighed and hand filled into empty gelatin shells to obtain 500 mg VA extract per capsule. The tablets/capsules were evaluated for physicochemical properties, in vitro dissolution test and the data obtained were subjected to drug release kinetics. Fourier transform infrared spectroscopy (FTIR) test was done to investigate for drug – excipients compatibility. All granules were free flowing with angle of repose ≤ 30.2 ± 0.10 and Carr’s index 15.5 ± 0.1%. The hardness of the tablets increased generally as the concentration of the binders increased. The friability of the formulated tablets were ≤ 0.01 % and hence non friable. The disintegration time of both tablets and capsules increased with increase in binder concentrations, but none disintegrated within the 15 min for conventional solid dosage forms. The drug release was dependent on the type and concentration of the binders. The release from the capsule and tablet formulations at 45 min falls short of the 75 % pharmacopoeia requirements for conventional drugs. Drug release kinetics of the VA extract tablets showed a zero order release rate, whilst those of the capsules showed a first order release rate. The FTIR test showed no noticeable interaction between the active ingredient (VA leaf extract) and the excipients used in the formulation. This study has been able to standardize the hypoglycemic dose of VA leaf extract for the management of diabetes mellitus to be 500 mg tablet/capsule to be taken 2 times daily. The VA leaf extract has been formulated into pharmaceutical tablet/capsule dosage forms which may be used in the management of diabetes mellitus.

Keywords: Vernonia amygdalina, Tablet, Capsule, Carnauba wax, Eudragit.