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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Administration, Oral, Animals, Biological Availability, Chemistry, Pharmaceutical, Gastrointestinal Tract, Male, Naltrexone, Narcotic Antagonists, Phosphatidylcholines, Quaternary Ammonium Compounds, Random Allocation, Rats, Rats, Sprague-Dawley, X-Ray Diffraction.
user
Does bioavailability of oral methylnaltrexone increase with a phosphatidylcholine-based formulation? Context: Methylnaltrexone (MNTX), a peripherally restricted opioid antagonist with mu-opioid receptor selectivity, can reduce opioid activity in the gastrointestinal tract while sparing the pain relief afforded by opioids. Since the bioavailability of oral MNTX is low, it is necessary to explore the oral formulations of MNTX that increase its bioavailability. An MNTX-phosphatidylcholine complex (MNTX-PC) formulation was prepared. The physicochemical properties of MNTX-PC were analyzed, and its bioavailability was evaluated in rats. After 250 mg/kg of oral MNTX-PC, plasma samples were collected up to 9 h. The concentrations of the compound in rat plasma were quantified using LC/MS/MS. Two MNTX plasma concentration peaks were observed at 120 and 180 min for the MNTX-PC group and control (MNTX in a water solution). Tmax was 180 min, C(max) was 1083.7 ± 293.9 ng/mL, and T(½) was 496 min for the MNTX-PC group. For control, T(max) was 180 min, C(max) was 448.4 ± 126.0 ng/mL, and T(½) was 259 min. The AUC₀₋₅₄₀ min for the MNTX-PC group was 5758.2 ± 1474.2 ngh/mL; for control, 1405.9 ± 447.8 ngh/mL. Thus, the relative bioavailability after the oral administration of MNTX-PC was 410% compared to that of control.
assistant
MNTX-PC formulation significantly enhanced the oral bioavailability of MNTX. Final Decision: yes