From the Research
The half-life of haloperidol is approximately 3.9 days after chronic administration, with a range of 1.2-2.3 days in 58% of patients and longer than 3 days in 42% of patients, as reported in the most recent and highest quality study 1.
Factors Affecting Half-Life
The half-life of haloperidol can be affected by several factors, including:
- Age
- Liver function
- Genetic variations in metabolizing enzymes, such as CYP2D6 and CYP3A5
- Concurrent medications
- Race, with African-Americans having a longer half-life 1
Comparison with Other Studies
Other studies have reported varying half-lives for haloperidol, ranging from 14.5-36.7 hours after a single oral dose 1, 17.5 +/- 8.7 hours for oral administration and 15.1 +/- 2.5 hours for intravenous administration 2, and 30 hours in terminally ill patients 3.
Clinical Implications
Understanding the half-life of haloperidol is important for appropriate dosing schedules and anticipating how long side effects might persist after discontinuation. The extended half-life of haloperidol decanoate, ranging from 3 to 4 weeks, means that steady-state plasma concentrations are typically achieved after 2-4 months of regular dosing with the injectable form 4.
Key Points
- The half-life of haloperidol can vary significantly between individuals
- Chronic administration of haloperidol can result in a longer half-life compared to single-dose administration
- Factors such as age, liver function, and genetic variations can affect the half-life of haloperidol
- Understanding the half-life of haloperidol is crucial for optimal dosing and management of side effects.