Absorption Oral metronidazole is well absorbed; topical application is less complete and more prolonged. Following administration, T max is 1 to 2 h, and C max is 25 mg/mL. Oral bioavailability is not affected by food, but peak serum levels will be delayed to 2 h.
Distribution Metronidazole appears in cerebrospinal fluid, saliva, and breast milk in concentrations similar to those found in plasma. Less than 20% is protein bound.
Metabolism Metabolites are 2–hydroxymethyl and acidic metabolite.
Elimination Routes of elimination are via urine (60% to 80%) and feces (6% to 15%). Renal Cl is approximately 10mL/min per 1.73m2 . The t ½ is 8 h in healthy adults, and the hydroxy-metabolite t ½ is 15 h.
Special Populations Hepatic Function Impairment Patients with hepatic function impairment metabolized metronidazole slower; accumulation of drug may occur. Cautiously administer doses below the usual recommended dose.
Elderly Because the pharmacokinetics of metronidazole may be altered in the elderly, monitoring of serum levels may be necessary to adjust the dosage accordingly.
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