Related Experiment Videos
Enhanced bioavailability of morphine after rectal administration in rats
Y Katagiri1, T Itakura, K Naora
1Department of Pharmacy, Shimane Medical University Hospital, Izumo, Japan.
The Journal of Pharmacy and Pharmacology
|December 1, 1988
Summary
Rectal administration of morphine hydrochloride in rats resulted in significantly higher bioavailability (approximately 90%) compared to oral administration (approximately 10%). This highlights the potential of rectal delivery for enhanced morphine absorption.
Area of Science:
- Pharmacology
- Drug Delivery Systems
- Pharmacokinetics
Background:
- Morphine is a potent opioid analgesic with variable oral bioavailability.
- Understanding alternative administration routes is crucial for optimizing therapeutic efficacy.
- Rectal drug administration offers potential for improved absorption and reduced first-pass metabolism.
Purpose of the Study:
- To compare the bioavailability of morphine hydrochloride administered via intravenous, oral, and rectal routes in Wistar rats.
- To evaluate the impact of rectal administration site (unrestricted vs. restricted) on morphine bioavailability.
- To determine the systemic availability of morphine following rectal versus oral administration.
Main Methods:
- Male Wistar rats (10-11 weeks old) received morphine hydrochloride intravenously (10 mg/kg), orally (100 mg/kg), or rectally (10 mg/kg, unrestricted or restricted).
- Plasma morphine concentrations were measured over time.
- Area under the plasma concentration-time curve (AUC) was calculated to determine pharmacokinetic parameters.
- Systemic availability was estimated by comparing AUC values normalized to dose.
Main Results:
- Oral administration of morphine resulted in low systemic availability (approximately 10% of intravenous).
- Rectal administration, both unrestricted and restricted, yielded high systemic availability (approximately 90% of intravenous).
- AUC values for rectal administration were comparable to intravenous administration, significantly higher than oral.
Conclusions:
- Rectal administration of morphine hydrochloride provides significantly enhanced systemic bioavailability in rats compared to oral administration.
- The rectal route, irrespective of the administration site within the tested range, offers a viable alternative for achieving high morphine absorption.
- These findings suggest that rectal delivery could be a more effective route for morphine administration, potentially improving pain management outcomes.