Development of dimenhydrinate liquid filled coated hard gelatin capsule for rectal application : an alternative for tropical zone

Abstract

Develops rectal capsule dosage form using dimenhydrinate as a model drug. The various types of capsule, liquid vehicles for filling into capsule were selected and formulated to give appropriate characteristics in particular drug release properties. The liquid preparation was filled into hard gelatin capsule and coated with the cellulose and the polyacrylate, using perforated pan coater and fluidized bed coater. The comparative studies of types of polymer, types and amount of plasticizers and coating equipments employed for capsule coating were also performed. The stability of rectal capsule was assessed by storage at 35 ํC, 45 ํC and room temperature, 75% RH for 4 months. Licaps was the best type of hard gelatin capsule for preventing liquid leakage. Mineral oil was the most appropriate liquid vehicle for filling into capsule due to non-moisture absorption, having no effect on capsule shell, having appropriate viscosity and surface tension. Aerosil 200 as thickener could reduce liquid leakage due to greater viscosity and thixotropy. The addition of Tween80 or Cremophor RH40 and dextrose into the preparations could produce drug release comparable to markets product (Gravol, dimenhydrinate suppository). The selected formula containing 5% Tween80, 2.5% Aerosil 200, 10% dextrose in mineral oil exhibited appropriate viscosity and flowability to obtain excellent weight variation in the range of +- 5% when filling into capsule. Cellulose film (HPMC) gave the better smooth and continuous film and produced excellent gliding effect when compared to polyacrylate film (Eudragit L 30D-55). Additionally, Eudragit L 30D-55 was not suitable for hard gelatin capsule coating because the capsule became brittle and prolonged disintegration as well as dissolution time. Fluidized bed coater was better than perforated pan coater for capsule coating since the distribution of the coated film was achieved quickly and homogeneously. The incoporation of diethylpthalate as plasticizer could improve the water vapor permeability of HPMC film. For the stability study, it was found that drug content was remained unchanged after four month storage at room temperature and at 35 ํC but the darker yellow preparation was observed especially at high temperature. It was observed that the amount of drug in preparation was slightly decreased at 45 ํC and the release of drug slightly decreased with increasing storage time.