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Human Pharmacokinetics and Comparative Bioavailability of Loperamide Hydrochloride
Author(s) -
KILLINGER JOANNE M.,
WEINTRAUB HOWARD S.,
FULLER BARBARA L.
Publication year - 1979
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1979.tb01654.x
Subject(s) - bioavailability , pharmacokinetics , loperamide , pharmacology , medicine , diarrhea
A pharmacokinetic study of the antidiarrheal agent loperamide hydrochloride (Imodium) was conducted in six male subjects. The study utilized a random crossover design and employed a 2-mg capsule and a 0.2-mg/ml syrup formulation. Each treatment consisted of a single oral dose of 8 mg loperamide HCl followed by a two-week interval before the next treatment. Serum and urine samples obtained at various times after drug administration were assayed for loperamide using a radioimmunoassay specific for the drug. The mean biologic half-life, calculated from the elimination phase of the log serum concentration-versus-time data, was 10.8 +/- 0.6 hours for the overall study, 10.2 +/- 0.6 hours for the syrup formulation, and 11.2 +/- 0.8 hours for the capsules. The loperamide from the syrup was absorbed more rapidly than from the capsule formulation, with the peak serum levels observed at a mean time of 2.4 +/- 0.7 hours for the syrup and 5.2 +/- 0.3 hours for the capsule formulation. The relative areas under the serum loperamide concentration-versus-time curves suggested that the two formulations have comparable physiologic availability. The maximum observed serum concentrations were also similar, indicating the safety of the syrup formulation. Excretion of approximately 1 per cent of the dose in the urine as unchanged loperamide after seven days was observed independent of the particular dosage form that was administered.