Objective—To determine the plasma pharmacokinetics
of imipenem (5 mg/kg) after single-dose IV, IM,
and SC administrations in dogs and assess the ability
of plasma samples to inhibit the growth of Escherichia
coli in vitro.
Animals—6 adult dogs.
Procedure—A 3-way crossover design was used.
Plasma concentrations of imipenem were measured
after IV, IM, and SC administration by use of high-performance
liquid chromatography. An agar well antimicrobial
assay was performed with 3 E coli isolates
that included a reference strain and 2 multidrug-resistant
Results—Plasma concentrations of imipenem
remained above the reported minimum inhibitory concentration
for E coli (0.06 to 0.25 µg/mL) for a minimum
of 4 hours after IV, IM, and SC injections.
Harmonic mean and pseudo-standard deviation halflife
of imipenem was 0.80 ± 0.23, 0.92 ± 0.33, and
1.54 ± 1.02 hours after IV, IM, and SC administration,
respectively. Maximum plasma concentrations (Cmax)
of imipenem after IM and SC administration were
13.2 ± 4.06 and 8.8 ± 1.7 mg/L, respectively. Time
elapsed from drug administration until Cmax was 0.50
± 0.16 hours after IM and 0.83 ± 0.13 hours after SC
injection. Growth of all 3 E coli isolates was inhibited
in the agar well antimicrobial assay for 2 hours after
imipenem administration by all routes.
Conclusions and Clinical Relevance—Imipenem is
rapidly and completely absorbed from intramuscular
and subcutaneous tissues and effectively inhibits in
vitro growth of certain multidrug-resistant clinical isolates
of E coli. (Am J Vet Res 2003;64:694–699)