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Bioavailability of the antiemetic metopimazine given as a microenema
J Herrstedt1, M Jørgensen, H R Angelo
1Department of Oncology, Herlev Hospital, University of Copenhagen, Denmark.
Abstract:
The absorption of the antiemetic metopimazine (MPZ) given as a single dose of (a) 40 mg microenema, (b) 40 mg orally and (c) 10 mg as a 60 min i.v. continuous infusion was investigated in six healthy volunteers. Blood samples were drawn and the serum concentrations of MPZ and its acid metabolite were measured. The bioavailability of MPZ given orally and as enemas was 22.3 and 19.5% respectively. Partial avoidance of hepatic first pass metabolism was seen with the enemas, which in contrast to suppositories, seems to represent a reliable form of rectal administration.
Insights
This study compared metopimazine (MPZ) absorption via microenema, oral, and IV routes in healthy volunteers. Rectal administration via microenema offered partial avoidance of first-pass metabolism, suggesting reliable drug delivery.
Area of Science:
- Pharmacology
- Gastroenterology
- Drug Metabolism
Background:
- Metopimazine (MPZ) is an antiemetic drug.
- Understanding its absorption is crucial for effective therapeutic use.
- Rectal drug administration can bypass hepatic first-pass metabolism.
Purpose of the Study:
- To investigate the absorption and bioavailability of metopimazine (MPZ).
- To compare MPZ absorption following oral, microenema, and intravenous administration.
- To assess the impact of rectal administration on hepatic first-pass metabolism.
Main Methods:
- Six healthy volunteers received single doses of MPZ.
- Administration routes included 40 mg microenema, 40 mg orally, and 10 mg IV infusion.
- Serum concentrations of MPZ and its acid metabolite were measured.
Main Results:
- Oral MPZ bioavailability was 22.3%; microenema bioavailability was 19.5%.
- Microenema administration showed partial avoidance of hepatic first-pass metabolism.
- Rectal administration via microenema appears reliable.
Conclusions:
- Metopimazine exhibits moderate oral bioavailability.
- Microenema administration provides a reliable rectal route for MPZ, bypassing some hepatic metabolism.
- This suggests potential advantages for rectal delivery in specific clinical scenarios.