From the Guidelines
To switch from fluphenazine long-acting injectable (LAI) to haloperidol LAI, start haloperidol decanoate at 10-15 times the oral haloperidol equivalent dose of the patient's current fluphenazine dose. When making this switch, it's crucial to consider the patient's previous medication experience, personal preference, history of treatment response, and pharmacokinetic properties, as suggested by 1. The key steps in this transition include:
- Calculating the equivalent oral haloperidol dose based on the current fluphenazine dose
- Initiating haloperidol decanoate at the calculated dose, for example, if a patient is on fluphenazine decanoate 25mg every 2 weeks, initiate haloperidol decanoate at 100-150mg every 4 weeks
- Administering the first haloperidol LAI dose at the time the next fluphenazine LAI would have been due
- Monitoring the patient closely for 2-3 months as haloperidol reaches steady state, with consideration for oral haloperidol supplementation if breakthrough symptoms occur
- Adjusting the haloperidol LAI dose based on clinical response and side effects after 2-3 months, taking into account the potential for extrapyramidal symptoms and the need to avoid unnecessary use of anticholinergic agents like benztropine or trihexyphenidyl, as noted in 2. This approach is based on the understanding that both medications are first-generation antipsychotics with similar mechanisms of action, though they have different potencies and pharmacokinetic profiles, with haloperidol decanoate having a longer half-life than fluphenazine decanoate, allowing for less frequent administration.
From the Research
Switching from Fluphenazine LAI to Haloperidol LAI
To switch from fluphenazine LAI to haloperidol LAI, several factors need to be considered, including the current extent of antipsychotic exposure, the kinetics of the LAI preparation, and the expected plasma levels achieved by the LAI formulation 3.
- Understanding the kinetics of LAI preparations: The kinetics of haloperidol decanoate and fluphenazine decanoate have been studied, with a dosage equivalency of 3:1 between the two drugs 4.
- Expected plasma levels: Plasma concentrations of haloperidol and fluphenazine can be monitored using ultra high pressure liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) 5.
- Clinical considerations: When switching from one LAI antipsychotic to another, it is essential to consider the potential risks and benefits, including the risk of treatment discontinuation, weight gain, and increases in prolactin levels 6.
- Dosage and administration: The dosage and administration of haloperidol decanoate and fluphenazine decanoate have been compared in clinical trials, with no significant differences in therapeutic effect found between the two drugs 4.
Key Considerations
- The decision to switch from fluphenazine LAI to haloperidol LAI should be based on individual patient needs and circumstances.
- Close monitoring of plasma antipsychotic levels and clinical response is recommended when switching between LAI antipsychotics 3.
- The potential risks and benefits of switching, including the risk of treatment discontinuation and changes in plasma levels, should be carefully considered 6.