The effect of polymorphism on powder compaction and dissolution propertiesof chemically equivalent oxytetracycline hydrochloride powders

In South Africa, oxytetracycline is identified as an essential drug; many g eneric products are on the market, and many more are being developed In thi s study, six oxytetracycline hydrochloride powders were obtained randomly f rom manufacturers, and suppliers were compared. It was found that complianc e to a pharmacopoeial monograph was insufficient to ensure the optimum diss olution performance of a simple tablet formulation. Comparative physicochem ical raw material analysis showed no major differences with regard to diffe rential scanning calorimetry (DSC), infrared (IR) spectroscopy, powder diss olution, and particle size. However, the samples could be divided into two distinct types with respect to X-ray powder diffraction (XRD) and thus poly morphism. The two polymorphic forms had different dissolution properties in water or 0.1 N hydrochloride acid. This difference became substantial when the dissolution from tablets was compared. The powders containing form A w ere less soluble than that containing form B.