Combined eutexia and amorphization for simultaneous enhancement of dissolution rate of triamterene and hydrochlorothiazide: preparation of orodispersible tablets.

Background: Triamterene is an oral antihypertensive drug with dissolution-limited poor bioavailability. It can be used as monotherapy or in fixed dose combination with hydrochlorothiazide which also suffers from poor dissolution. Moreover, co-processing of drugs in fixed dose combination can alter their properties. Accordingly, pre-formulation studies should investigate the effect of co-processing and optimize the dissolution of drugs before and after fixed dose combination. This is expected to avoid deleterious interaction (if any) and to hasten the biopharmaceutical properties.

Objective: Accordingly, the aim of this work was to optimize the dissolution rate of triamterene alone and after fixed dose combination with hydrochlorothiazide.

Methodology: Triamterene was subjected to dry co-grinding with xylitol, HPMC-E5 or their combination. The effect of co-grinding with hydrochlorothiazide was also tested in absence and presence of xylitol and HPMC-E5. The products were assessed using Fourier-transform infrared (FTIR), differential scanning calorimetry, X-ray powder diffraction (XRPD), in addition to dissolution studies. Optimum formulations were fabricated as oral disintegrating tablets (ODT).Results: Co-processing of triamterene with xylitol formed eutectic system which hastened dissolution rate. HPMC-E5 resulted in partial amorphization and improved triamterene dissolution. Co-grinding with both materials combined their effects. Co-processing of triamterene with hydrochlorothiazide resulted in eutexia but the product was slowly dissolving due to aggregation. This problem was vanished in presence of HPMC-E5 and xylitol. Compression of the optimum formulation into ODT underwent fast disintegration and liberated acceptable amounts of both drugs.

Conclusion: The study introduced simple co-processing with traditional excipients for development of ODT of triamterene and hydrochlorothiazide.