Metronidazole kinetics in dialysis patients

Area of Science:

• Pharmacokinetics
• Clinical Pharmacology
• Drug Metabolism

Background:

• Metronidazole (MET) is an antibiotic commonly used to treat anaerobic bacterial and protozoal infections.
• Understanding MET pharmacokinetics in patients with renal insufficiency is crucial for appropriate dosing and minimizing adverse effects.

Purpose of the Study:

• To investigate the impact of renal insufficiency on metronidazole (MET) disposition and its metabolites.
• To evaluate the efficacy of hemodialysis in clearing MET and its metabolites.

Main Methods:

• A single 500 mg intravenous dose of metronidazole (MET) was administered to healthy volunteers (NOR) and patients with renal insufficiency (REN).
• Plasma concentrations of MET, acetic acid metabolite (MTAC), and hydroxymethyl metabolite (MTOH) were measured using high-pressure liquid chromatography.
• Pharmacokinetic analysis was performed using a two-compartment open model; hemodialysis clearance was also assessed.

Main Results:

• Plasma MET concentrations and pharmacokinetic parameters (volume of distribution, half-life, clearance) were similar between NOR and REN groups.
• Renal insufficiency was associated with significantly higher peak concentrations of MTAC (fivefold) and MTOH (twofold).
• Hemodialysis demonstrated moderate clearance of MET (2.9–4.2 L/hr), MTAC (5.8–7.8 L/hr), and MTOH (2.7–5.6 L/hr), removing approximately 50% of the dose over 8 hours.

Conclusions:

• Renal failure does not significantly alter metronidazole (MET) pharmacokinetics but leads to accumulation of its metabolites.
• Dose reduction of MET may be necessary in patients with renal insufficiency due to metabolite accumulation.
• Hemodialysis can effectively remove metronidazole and its metabolites, suggesting its utility in managing overdose or toxicity.