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Characterization of Hydrochlorothiazide-Trometamol Mixtures

Formulation of fast release and soluble tablets

Khairy E. Gabr and Thanaa M. E. Borg

Department of Pharmaceutics, Faculty of Pharmacy, Mansoura University, Mansoura (Egypt)

Co-precipitated and physical mixtures of hydrochlorothiazide (HCT) and trometamol (tromethamine, Tris) were examined using Fourier-transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction. The solubility of HCT in distilled water was increased in the presence of Tris. Results of the examinations indicated that HCT, co-precipitated with Tris in the solid state, forms complexes. Tablets made from co-precipitates showed improved drug dissolution rates (at constant surface) with a maximum at 30 % HCT (w/w) content. Maximum relative enhancements (10.5 and 5.25) were obtained in distilled water and 0.1 N HCl, respectively. Tablets containing HCT-Tris (3 : 7) co-precipitates exhibited a faster dissolution rate compared to those without Tris. Co-precipitate tablets containing microcrystalline cellulose (Avicel PH101) as diluent gave higher release rates than tablets containing lactose or mannitol. Therefore, Avicel PH101-containing tablets can be used for fast drug release. Co-precipitate tablets containing mannitol or lactose showed high solubility of HCT in distilled water (320 mg/100 ml); one tablet could be dissolved in 10 ml distilled water. These tablets can be used as soluble dosage form for patients unable to swallow tablets.

Key words Fast release tablets · Hydrochlorothiazide · Soluble tablets · Tablet formulations · Trometamol, co-precipitates