Effect of oil extract of marigold on rheological parameters and pharmaceutical availability of morphine hydrochloride from model ointments
Zakład Farmacji Aptecznej, Katedra Farmacji Stosowanej, Uniwersytet Medyczny w Łodzi
Introduction. The presence of opioid receptors in peripheral tissues enabled topical application of morphine or other opioid analgesics on pathologically changed skin or mucous membranes. In the process of local treatment of painful pathologic conditions not only removing of pain is of importance but facilitating wound healing as well. Extracts of marigold demonstrate such activity.
Aim. To develop analgesic ointments with morphine hydrochloride (MH) and oil (paraffin) extract of marigold inflorescence, to test their physicochemical properties and pharmaceutical availability of morphine salt from model ointments of different percentage of the extract.
Material and methods. Vehicles and ointments produced in eucerine base differing in the contents of liquid paraffin or oil extract of marigold (ME) were tested. Extensometric method was used to test spreadness of the preparations. Potentiometric method was applied to measure pH of the produced ointments. Viscisity parameters were determined with cone-plate digital rheometer. The test for morphine pharmaceutical availability was performed with spectrophotometric method.
Results. Morphine hydrochloride (MH) and oil extract of marigold (ME) decrease pH of the ointment but it remains within the range tolerated by skin. Extensibility increases and viscosity decreases together with the increase of ME content. The model ointments are strongly thixotropic. MH releases less effectively from ointments of higher ME concentration.
Conclusions. With the increase of liquid paraffin concentration in ointments without ME, constants of MH rate of diffusion increase. The relation between ME concentration and the constant of MH rate of diffusion is reverse.
Key words: ointments, morphine hydrochloride, oil extract of marigold, pharmaceutical availability, rheological parameters