Pharmacokinetics of i.m. glycopyrronium

A sensitive radioreceptor assay was used to determine the pharmacokinetics of glycopyrronium following a single i.m. injection of 8 micrograms kg-1 in nine surgical patients. Rapid absorption was found, with a mean peak plasma concentration after 16.1 min and mean elimination half-life of 75.4 min. Almost half (49.3%) of the drug was excreted in pharmacologically active form in the urine within 3 h. A significant increase in heart rate (P less than 0.05) occurred in 15 min, lasting up to 60 min, and an antisialagogue effect in 10 min, lasting up to 8 h (P less than 0.05). There was no measurable glycopyrronium in lumbar cerebrospinal fluid samples (n = 9) taken 40 min after administration of drug.