Serum Aripiprazole Concentrations After Inadvertent Intradeltoid Administration of Aripiprazole Lauroxil 1064 mg: A...

The FDA-approved package insert for aripiprazole lauroxil (AL) indicates that the 1064-mg dose should be administered as an intramuscular injection in the gluteal muscle every 8 weeks. Administration at different sites may change how the drug is absorbed and eliminated, thereby altering the peak medication level, half-life, and time to next injection. Currently, there is a dearth of published reports that describe the pharmacokinetics of this dose when administered at an injection site other than the gluteal muscle.

A patient inadvertently received the first injection of AL 1064 mg in the deltoid muscle. Given the absence of pharmacokinetic data for this administration site, serial serum aripiprazole concentrations were obtained to assist in determining the best course of treatment.

Intradeltoid administration was associated with a higher observed maximum concentration (C max ), a similar time to reach C max (t max ), and prolonged exposure. Confounding variables may have affected the data. Based on the medication levels, the next injection was delayed until 13 weeks after the initial injection.

This case report is the first to describe how the pharmacokinetics of AL 1064 mg are altered when inadvertently administered in the deltoid muscle.