Nasal administration of morphine-6-glucuronide in sheep--a pharmacokinetic study

The pharmacokinetics of morphine-6-glucuronide (M6G) after both intravenous dosing and nasal administration were studied in sheep. The nasal formulation consisted of M6G in combination with an absorption promoting delivery system in the form of chitosan. The mean half-life of M6G after intravenous administration was 51.0 +/- 8.2 min and that after intranasal dosing was 45.0 +/- 5.5 min. M6G clearance and volume of distribution were 5.4 +/- 1.5 mL min-1 kg-1 and 0.4 +/- 0.1 L kg-1 respectively. The plasma profile after nasal administration demonstrated rapid absorption of M6G. The bioavailability of M6G in the chitosan formulation was found to be 31.4%. These results suggest that M6G administered in combination with the chitosan delivery system may be considered as a suitable non-parenteral means of administering this analgesic.