Preparation for Child Psych PRITE and Boards
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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).

Use in Children

  • Haloperidol was approved for use in children prior to the Pediatric Research Equity Act of 2003. (which allowed FDA to mandate the pharmacological companies to research pediatric safety and efficacy of medications)
    • haloperidol carries extrapolated "FDA approval" for psychosis for children as young as 3 y.o., while actual research amounts to only moderate and low quality of evidence for this drug.
  • While commonly used as a PRN for agitation on adult psychiatric units, pediatric inpatient units often use chlorpromazine due to higher risk of dystonia associated with haloperidol in anti-psychotic naive patients.


  • 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.

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)

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 0.5, 1, 2, 5, 10, and 20 mg tablets.
  • The oral solution of haloperidol lactate 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.


1. Kudo S, Ishizaki T. Pharmacokinetics of haloperidol: an update. Clin Pharmacokinet. 1999 Dec;37(6):435-56.