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Pol J Cosmetol 2012, 15(4): 272-278pl  The influence of one year storage on rheological parameters and pharmaceutical availability of morphine hydrochloride from anhydrous absorptive ointmentsGrażyna Samczewska Zakład Farmacji Aptecznej, Katedra Farmacji Stosowanej, Uniwersytet Medyczny w Łodzi Summary Introduction. Morphine hydrochloride and morphine sulphate are pharmacopoeial morphine salts used in polish medical treatment. They are stable in solid state in the absence of water. They degrade easily under the effect of water and oxygen dissolved in it. Propane-1,2-diol (propylene glycol) is an alternative solvent for morphine salts in topical formulations. Aim. The purpose of a research was to examine not only the pH, rheological properties from produced vehicles and ointments, but also the rate of released morphine hydrochloride from none-water ointments through semipermeable membrane to water, after one year storage. Material and methods. After a one year period there were tested vehicles and ointments of different content of white soft paraffin, anhydrous lanolin but constant content of propylene glycol (vehicle) or glycol solution of morphine hydrochloride (ointment). Extensibility of the formulations was determined by extensometric method; pH by potentiometric method. Viscosity parameters were determined using a digital cone-plate rheometer. Pharmaceutical availability of morphine was tested by spectrophotometric method. Results. Small rise of pH, increase of viscosity and tixotropy, decrease of perspiration number, extensibility and yield stress change were noticed after a one year storage. Pharmaceutical availability of morphine still was the highest from ointment of 16% content of lanolin. Key words: anhydrous absorptive ointments, morphine hydrochloride, propylene glycol, rheology, pharmaceutical availability |