Summary
Urinary pharmacokinetics of3H-Physostigmine (Phy) were studied in rat after an intramuscular administration of 650 μ/kg. Urine was collected at 0–1, 1–2, 2–4, 4–6, and 6–24 hr and every 24 hr for seven days. The rats were sacrificed by decapitation and the tissues were analyzed for radioactivity. Less than one percent (.87%) of the dose remained in tissues after the seventh day. Liver, followed by kindney, accounted for the highest activity compared to other tissues. The amounts of3H-Phy and metabolites were determined by HPLC and the rapid decline of Phy in urine was observed. Most of t h e radioactivity found in the urine was due to metabolites (47% of dose in 24 hr) indicating extensive metabolism. The cumulative percent of radioactivity excreted in the urine was 30.3±12.6% in 6 hr, 44.4± 13.1% in 24 hr which increased to 52.7 ± 12.0% after seven days.
Urinary elimination rate constant (Ku) of Phy was found to be .051±.009 hr−1 indicating that the urinary elimination of Phy accounted for a minor part (2.5–4.%) of the systemic elimination
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Presented to the Pharmacology Society in Boston, August 1985.
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Somani, S.M., Boyer, A. Urinary pharmacokinetics of physostigmine in the rat. European Journal of Drug Metabolism and Pharmacokinetics 10, 343–347 (1985). https://doi.org/10.1007/BF03189763
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DOI: https://doi.org/10.1007/BF03189763