Following accepted general principles, haloperidol should be given during pregnancy only if the benefit to the mother clearly outweighs the potential fetal risk.Haloperidol is excreted in breast milk. A few studies have examined the impact of haloperidol exposure on breastfed infants and in most cases, there were no adverse effects on infant growth and development. Other considerations
During long-term treatment of chronic psychiatric disorders, the daily dose should be reduced to the lowest level needed for maintenance of remission. Sometimes, it may be indicated to terminate haloperidol treatment gradually. In addition, during long-term use, routine monitoring including measurement of BMI, blood pressure, fasting blood sugar, and lipids, is recommended due to the risk of side effects.Other forms of therapy (psychotherapy, occupational therapy/ergotherapy, or social rehabilitation) should be instituted properly. PET imaging studies have suggested low doses are preferable. Clinical response was associated with at least 65% occupancy of D2 receptors, while greater than 72% was likely to cause hyperprolactinaemia and over 78% associated with extrapyramidal side effects. Doses of haloperidol greater than 5 mg increased the risk of side effects without improving efficacy. Patients responded with doses under even 2 mg in first-episode psychosis. For maintenance treatment of schizophrenia, an international consensus conference recommended a reduction dosage by about 20% every 6 months until a minimal maintenance dose is established. Depot forms are also available; these are injected deeply intramuscularly at regular intervals.
The mean T1/2 is 20.7 hours. The decanoate injectable formulation is for intramuscular administration only and is not intended to be used intravenously. The plasma concentrations of haloperidol decanoate reach a peak at about six days after the injection, falling thereafter, with an approximate half-life of three weeks. Intravenous injections
The bioavailability is 100% in intravenous (IV) injection, and the very rapid onset of action is seen within seconds. The T1/2 is 14.1 to 26.2 hours. The apparent volume of distribution is between 9.5 and 21.7 L/kg. The duration of action is four to six hours. Therapeutic concentrations
Plasma levels of five to 15 micrograms per liter are typically seen for therapeutic response (Ulrich S, et al. Clin Pharmacokinet. 1998). The determination of plasma levels is rarely used to calculate dose adjustments but can be useful to check compliance. The concentration of haloperidol in brain tissue is about 20-fold higher compared to blood levels. It is slowly eliminated from brain tissue,  which may explain the slow disappearance of side effects when the medication is stopped. Distribution and metabolism
Haloperidol is heavily protein bound in human plasma, with a free fraction of only 7.5 to 11.6%. It is also extensively metabolized in the liver with only about 1% of the administered dose excreted unchanged in the urine. The greatest proportion of the hepatic clearance is by glucuronidation, followed by reduction and CYP-mediated oxidation, primarily by CYP3A4. History
Haloperidol was discovered by Paul Janssen.