Real-world use patterns of olanzapine long-acting injection in the United States: comparison to the recommended dosing strategy.

OBJECTIVE

Recommended doses for olanzapine long-acting injection (olanzapine LAI) are 150 mg/2 weeks, 210 mg/2 weeks, 300 mg/2 or 4 weeks, and 405 mg/4 weeks. This analysis evaluated the dosing and interval patterns to compare the actual dosing patterns with the recommended dosing strategy.

RESEARCH DESIGN AND METHODS

These data, from March 2010 through September 2011, were collected as part of a Risk Evaluation and Mitigation Strategy mandatory patient registry that captures all post-approval olanzapine injections in the US. This registry includes both active and inactive (60 + days since last injection) patients.

RESULTS

All patients with at least one olanzapine injection were included (n = 1694). The mean number of injections received was 6.6 (range of 1-40). The most frequent numbers of injections were one (26.3%) and two (12.9%). For the 11,228 olanzapine injections, the most common doses were 300 mg and 405 mg, accounting for 92.9% of injections. Although the most common time intervals between injections was about 14 days for 150 mg, 210 mg, and 300 mg, and about 28 days for 405 mg, the intervals ranged from less than 10 to more than 60 days for all doses. Among active patients (48.2% of registry), 68.2% had >120 days of treatment with any dose, and the number of days since the last injection was around 2 weeks or less for 61.2% of patients, around 3 weeks for 16.5% of patients, and around 4 weeks for 7.1% of patients. Among inactive patients (51.8% of registry), 48.6% had <30 days of treatment. For the pattern of the first five injections, most patients (70.9%) received four subsequent injections of the same dose as their initial injection.

CONCLUSIONS

This registry will continue to change. There is a broad range in time between injections. Most patients continue to receive the same initial dose instead of switching to a maintenance dose. This may suggest that some clinicians are not reassessing the dose after the initial starting dose because the patient was stabilized on olanzapine oral before beginning olanzapine long-acting injection. The study is limited by a database that does not include reasons for dose and dosing interval decisions or reasons for delaying or discontinuing treatment.