Pharmacokinetics, safety, and tolerability of intramuscular ziprasidone in healthy volunteers

Little has been published regarding the pharmacokinetics of the intramuscular ( IM) formulation of Ziprasidone. The authors report results from 2 early phase I studies in healthy volunteers: a trial of single 5-, 10-, or 20-mg IM doses of ziprasidone in 24 subjects and an open-label 3-way crossover trial of 5-mg intravenous ( IV), 5-mg IM, and 20-mg oral ziprasidone in 12 subjects. Absorption of IM ziprasidone was rapid ( T-max < 1 hour). The IM pharmacokinetic profile was consistent between studies and linear, with dose-related increases in exposure observed. The mean IM elimination t(1/ 2) was short and approximately 2.5 hours. The mean bioavailability for the 5-mg IM ziprasidone dose was approximately 100%. Adverse events were generally mild to moderate, and no subjects were discontinued from the study. No significant effects on renal function or other laboratory values were noted. These results support the use of IM ziprasidone in treating acutely agitated patients with schizophrenia.