From the FDA Drug Label
Based upon a pharmacokinetic study in healthy volunteers, a 5 mg dose of intramuscular olanzapine for injection produces, on average, a maximum plasma concentration approximately 5 times higher than the maximum plasma concentration produced by a 5 mg dose of oral olanzapine
- The conversion of olanzapine from oral to intramuscular (IM) administration is not directly equivalent due to differences in peak plasma concentrations.
- A 5 mg dose of IM olanzapine produces a maximum plasma concentration approximately 5 times higher than a 5 mg dose of oral olanzapine.
- However, the area under the curve (AUC) achieved after an IM dose is similar to that achieved after oral administration of the same dose 1.
- The half-life observed after IM administration is similar to that observed after oral dosing 1.
From the Research
Conversion of Olanzapine from Oral to Intramuscular Administration
- The conversion of olanzapine from oral to intramuscular (IM) administration is not directly stated in the provided studies, but we can gather information about the dosing and efficacy of IM olanzapine compared to oral olanzapine 2, 3.
- A study comparing the efficacy and safety of olanzapine versus haloperidol during transition from IM to oral therapy found that IM olanzapine 10 mg and IM haloperidol 7.5 mg effectively reduced agitation over 24 hours, and this alleviation of agitation was sustained following transition to 4 days of oral treatment (5-20 mg/d for both) 2.
- Another study assessed the effectiveness and safety of oral olanzapine treatment transitioned from rapid-acting intramuscular olanzapine (RAIM) in patients with acute agitation associated with schizophrenia, and found that the reduction in agitation seen with RAIM was sustained with oral dose of olanzapine 3.
- The pharmacokinetics of olanzapine long-acting injection (OLAI) were also studied, and it was found that olanzapine concentrations were observed immediately upon injection, with a half-life of approximately 30 days, and steady state reached after approximately 3 months 4.
- It is worth noting that the dosing of IM olanzapine can vary, with some studies using 10 mg 2, 3 and others using higher doses such as 150,210, and 300 mg/2-week doses 4.
Key Findings
- IM olanzapine is effective in reducing agitation in patients with schizophrenia 2, 3.
- The efficacy of IM olanzapine is sustained when transitioned to oral treatment 2, 3.
- The pharmacokinetics of OLAI are characterized by a slow rate of intramuscular absorption and a half-life of approximately 30 days 4.
- The dosing of IM olanzapine can vary, and the optimal dose for conversion from oral to IM administration is not clearly established 2, 4, 3.