Contents
Introduction
This page contains clinically useful information, as well as some research data on Haldol. Complete prescriber's information is available on the internet.
Basic Info
Haloperidol (HPDL), is a high-potency and the most commonly prescribed first-generation antisphycotic, has only one pharmacologically active metabolite (i.e., reduced HPDL). Haloperidol also exerts sedative and antiemetic activity (blocking D2-R in the chemoreceptor trigger zone, similar to Reglan).
Plasma level
Data on correlation between HPDL plasma levels and response are mixed, with some studies suggesting that target plasma level of 10-15 ng/mL should be reached before medication trial is considered a failure. (Janicek Principles Psychopharm p.89)
Metabolism
- t1/2 is 10-30hrs.
- Metabolized largely by CYP450-3A4 and, thus, affected by inducers, such as rifampin. HPDL is a weak inhibitor of 2D6.(1)
- HPDL is not definitively teratogenic, but is excreted in breast milk and can create EPS in the fetus/baby. Benefit to Mom must outweigh the risk to the baby or fetus.
- Brain tissues concentration of HPDL is higher than other tissues; this can create persistence of EPS and other side effects after HPDL is discontinued.
HALDOL Decanoate
- Long-acting preparation of haloperidol, usually administered every 4 weeks. The solution is very thick, must use 20-22 gauge needle, max 3mL per injection per site. Inject into the gluteal region; remember to aspirate before pushing the medication - must not inject into a blood vessel.
- Patient must tolerate and respond to oral haloperidol before trying the long-acting decanoate.
- Conversion: Starting dose is 10-15 times the oral dose of haloperidol, with a maximum of 100mg in the initial injection. Effective IM dose is 10-20x the effective oral dose.
Side effects
- EPS
- Dystonia, tardive dystonia
- Tardive dyskinesia
- QTc prolongation
How supplied
- Oral haloperidol comes in 5, 10, and 20 mg tablets.
- The oral solution contains 2 mg haloperidol per ml
- HALDOL decanoate is supplied in 50mg/mL and 100mg/mL vials.
Black Belt Facts
- Several patients receiving haloperidol plus lithium developed an encephalopathic syndrome (weakness, lethargy, fever, tremulousness and confusion, EPS, leukocytosis, elevated serum enzymes, BUN, and FBS) followed by irreversible brain damage.
- HPLD can cause neutropenia and agranulocytosis, with several reports of deaths. Pre-existing low WBCs is a risk factor: monitor frequently.
Reference
1. Kudo S, Ishizaki T. Pharmacokinetics of haloperidol: an update. Clin Pharmacokinet. 1999 Dec;37(6):435-56.