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Bioavailability of oral methylnaltrexone increases with a phosphatidylcholine-based formulation

Dong-Hai Lin1, Chong-Zhi Wang, Li-Fang Qin

  • 1Department of Pharmaceutics, School of Pharmaceutical Science, Yantai University , Yantai , China.

Drug Development and Industrial Pharmacy
|January 19, 2013
PubMed
Abstract

Insights

A novel methylnaltrexone-phosphatidylcholine (MNTX-PC) complex formulation significantly improved oral bioavailability in rats. This MNTX-PC formulation offers a promising approach for enhanced oral delivery of methylnaltrexone.

Area of Science:

  • Pharmacology
  • Drug Delivery Systems
  • Gastroenterology

Background:

  • Methylnaltrexone (MNTX) is a peripherally restricted opioid antagonist that targets mu-opioid receptors.
  • MNTX reduces gastrointestinal opioid side effects while preserving central analgesia.
  • Low oral bioavailability of MNTX necessitates improved oral formulation strategies.

Purpose of the Study:

  • To develop and evaluate an oral formulation of MNTX with enhanced bioavailability.
  • To assess the pharmacokinetic profile of a methylnaltrexone-phosphatidylcholine (MNTX-PC) complex in rats.

Main Methods:

  • A methylnaltrexone-phosphatidylcholine (MNTX-PC) complex was synthesized and characterized.
  • Oral bioavailability of MNTX-PC was determined in rats following a single oral dose (250 mg/kg).
  • Plasma MNTX concentrations were quantified using LC/MS/MS over a 9-hour period.

Main Results:

  • The MNTX-PC formulation exhibited two plasma concentration peaks at 120 and 180 minutes.
  • Compared to MNTX in solution, MNTX-PC showed a 410% relative bioavailability.
  • Key pharmacokinetic parameters for MNTX-PC included Tmax of 180 min, Cmax of 1083.7 ± 293.9 ng/mL, and T½ of 496 min.

Conclusions:

  • The MNTX-PC formulation significantly enhances the oral bioavailability of methylnaltrexone.
  • This complex represents a promising strategy for improving oral MNTX delivery.
  • Further research may explore clinical applications of this enhanced formulation.

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