Pharmacokinetic parameters of morphine after ocular instillation versus intravenous administration

ABSTRACT

The route of administration of morphine, other than parenteral administration may be promising in increasing the compliance in patients that continuously need morphine for its analgesic effect. Morphine systemic penetration was investigated after ocular instillation. Its pharmacokinetic parameters and its bioavailability after ocular instillation compared to its intravenous administration were determined in healthy New Zealand albino rabbits. A cross over design was performed with an eight days wash-out period between the ocular and intravenous administrations. After ocular instillation, morphine was rapidly absorbed and attained serum levels compatible with effective concentration for its analgesic effect. Ocular bioavailability of morphine was high [66%]. Ocular administration of morphine could provide prolonged high serum levels and prolonged systemic pharmacologic effect. Ocular administration of morphine should be considered for its systemic pharmacologic effect