Jasmine Carpenter, PharmD, BCPS, BCPP PACT/Mental Health Clinical Pharmacy Specialist Department of Pharmacy and Mental Health Veterans Affairs Medical Center Washington, DC
Kong Kit Wong, PharmD Transitional Care Clinical Pharmacist Department of Clinical Pharmacy Services Kaiser Permanente of the Mid-Atlantic States Arlington, VA
Disclosures The authors report no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.
Currently, there is no concrete guidance on how to address missed doses of olanzapine long-acting injection; however, the pharmacokinetics of this formulation allow flexibility in dosing intervals. Therapeutic levels are present after the first injection, and the medication reaches steady-state levels in 3 months.35-37 As a result of its specific formulation, olanzapine pamoate long-acting injection provides sustained olanzapine pamoate plasma concentrations between injections, and has a half-life of 30 days.35 Consequently, therapeutic levels of the medication are still present 2 to 4 weeks after an injection.37 Additionally, clinically relevant plasma concentrations may be present 2 to 3 months after the last injection.36
In light of this information, if a patient has not reached steady state and has missed an injection, he or she should receive the recommended loading dose schedule. If the patient has reached steady state and it has been ≤2 months since the last dose, he or she should receive the next dose as soon as possible. If steady state has been reached and it has been >2 months since the last injection, the patient should receive the recommended loading dosing for 2 months (Figure 9). Because of the risk of post-injection delirium/sedation syndrome, and because therapeutic levels are achieved after the first injection, oral olanzapine supplementation is not recommended.
Use a stepwise approach
In general, clinicians can use a stepwise approach to managing missed doses of LAIAs (Figure 10). First, establish the number of LAIA doses the patient had received prior to the last dose, and whether these injections were administered on schedule. This will help you determine if the patient is in the initiation or maintenance phase and/or has reached steady state. The second step is to establish the date of the last injection. Use objective tools, such as pharmacy records or the medical chart, to determine the date of the last injection, rather than relying on patient reporting. For the third step, calculate the time that has passed since the last LAIA dose. Once you have completed these steps, use the specific medication recommendations described in this article to address the missed dose.
