No Long-Acting Injectable Formulation of Quetiapine is Available
Currently, there is no long-acting injectable (LAI) formulation of quetiapine (Seroquel) available for clinical use. The only extended-release formulation of quetiapine is the oral extended-release tablet (quetiapine XR), which allows for once-daily dosing rather than multiple daily doses of the immediate-release formulation 1, 2.
Available Quetiapine Formulations
- Quetiapine is available only in oral formulations: immediate-release (IR) tablets and extended-release (XR) tablets 3
- Quetiapine XR allows for once-daily oral administration, compared to the twice-daily dosing often required with the IR formulation 1, 2
- The XR formulation has similar bioavailability but provides prolonged plasma levels compared to the IR formulation 2
Benefits of Quetiapine XR Over Immediate Release
- Once-daily dosing schedule, which may improve medication adherence 1, 2
- Simplified treatment initiation with more rapid dose escalation possible 1
- Patients can be switched from IR to XR formulation at equivalent daily doses without clinical deterioration or compromise in tolerability 1
- Maintains the same efficacy profile as the IR formulation in schizophrenia and bipolar disorder 2, 4, 5
Long-Acting Injectable Antipsychotics Currently Available
While quetiapine does not have an LAI formulation, several other antipsychotics are available as long-acting injectables:
Clinical Implications
- For patients requiring less frequent administration than daily oral dosing, clinicians must consider switching to an available LAI antipsychotic rather than using quetiapine 3
- When adherence is a concern with quetiapine treatment, the XR formulation may offer some advantage with its once-daily dosing, but will not provide the extended coverage of an LAI 2
- LAIs in general have been shown to improve medication adherence compared to oral formulations, which may reduce relapse rates in conditions like schizophrenia 3
- Guidelines suggest that LAI formulations should be considered when patients have a history of non-adherence or express a preference for less frequent administration 3
Considerations When Switching From Quetiapine
If a patient currently on quetiapine requires an LAI antipsychotic due to adherence concerns:
- A careful cross-titration to another antipsychotic with an available LAI formulation would be necessary 3
- Selection of an alternative antipsychotic should consider the pharmacodynamic profile and side effect burden 3
- Patients should be monitored closely during the transition period for efficacy and tolerability 3
In summary, patients requiring less frequent administration than daily oral dosing will need to consider switching to an alternative antipsychotic medication that is available in a long-acting injectable formulation, as quetiapine is only available in oral formulations.