D2 Receptor

Haloperidol is a compound composed of a central piperidine structure with hydroxy and p-chlorophenyl substituents at position 4 and an N-linked p-fluorobutyrophenone moiety. It has a role as a serotonergic antagonist, a first generation antipsychotic, a dopaminergic antagonist, an antidyskinesia agent and an antiemetic. It is a hydroxypiperidine, an organofluorine compound, an aromatic ketone, a tertiary alcohol and a member of monochlorobenzenes.

Haloperidol has been used extensively for the treatment of psychotic disorders, and it has been suggested that the monitoring of plasma haloperidol concentration is clinically useful. Different assay methodologies have been used in research and clinical practice to examine the relationship between response and plasma concentration of the drug. Chemical assays such as high pressure liquid chromatography (HPLC) and gas-liquid chromatography (GLC) have good precision and sensitivity; radioimmunoassay (RIA) is generally more sensitive, but less precise and specific. Radioreceptor assay quantifies dopaminereceptor blocking activity but does not provide results comparable with those of HPLC, GLC and RIA. Large doses of haloperidol can safely be given intravenously and intramuscularly for rapid neuroleptisation; the bioavailability of this agent administered orally ranges from 60 to 65%. However, there is large interindividual, but not intraindividual, variability in plasma haloperidol concentrations and most pharmacokinetic parameters. This interindividual variability could be partially explained by the reversible oxidation/reduction metabolic pathway of haloperidol: it is metabolised via reduction to reduced haloperidol, which is biologically inactive. Different extents of enterohepatic recycling, and ethnic differences in metabolism, could also account for the observed variability in haloperidol disposition. Although not conclusive from different clinical studies, it appears that a plasma haloperidol concentration range of 4 micrograms/L to an upper limit of 20 to 25 micrograms/L produces therapeutic response. The role of reduced haloperidol in determining clinical response is not clear, although in some studies a high reduced haloperidol/haloperidol concentration ratio has been suggested to be associated with therapeutic failure. Measurements of red blood cell or cerebrospinal fluid haloperidol concentration have also been proposed as determinants of therapeutic response, but results from different studies are inconsistent, and do not seem to provide a significant advantage over plasma concentration monitoring. Physiological parameters such as prolactin and homovanillic acid levels have been evaluated, with the latter showing some promise that warrants further investigation. Haloperidol decanoate can be characterised by a flip-flop pharmacokinetic model because its absorption rate constant is slower than the elimination rate constant. Its plasma concentration peaks on day 7 after intramuscular injection. The elimination half-life is about 3 weeks, and the time to steady-state is about 3 months[1].

Absorption
Haloperidol is a highly lipophilic compound and is extensively metabolized in humans, which may cause a large interindividual variability in its pharmacokinetics. Studies have found a wide variance in pharmacokinetic values for orally administered haloperidol with 1.7-6.1 hours reported for time to peak plasma concentration (tmax), 14.5-36.7 hours reported for half-life (t1⁄2), and 43.73 μg/L•h [range 14.89-120.96 μg/L•h] reported for AUC. Haloperidol is well-absorbed from the gastrointestinal tract when ingested orally, however, the first-pass hepatic metabolism decreases its oral bioavailability to 40 - 75%. After intramuscular administration, the time to peak plasma concentration (tmax) is 20 minutes in healthy individuals or 33.8 minutes in patients with schizophrenia, with a mean half-life of 20.7 hours. Bioavailability following intramuscular administration is higher than that for oral administration. Administration of haloperidol decanoate (the depot form of haloperidol for long-term treatment) in sesame oil results in slow release of the drug for long-term effects. The plasma concentrations of haloperidol gradually rise, reaching its peak concentration at about 6 days after the injection, with an apparent half-life of about 21 days. Steady-state plasma concentrations are achieved after the third or fourth dose.

Route of Elimination
In radiolabeling studies, approximately 30% of the radioactivity is excreted in the urine following a single oral administration of 14C-labelled haloperidol, while 18% is excreted in the urine as haloperidol glucuronide, demonstrating that haloperidol glucuronide is a major metabolite in the urine as well as in plasma in humans.

Volume of Distribution
The apparent volume of distribution was found to range from 9.5-21.7 L/kg. This high volume of distribution is in accordance with its lipophilicity, which also suggests free movement through various tissues including the blood-brain barrier.

Clearance
Following intravenous administration, the plasma or serum clearance (CL) was found to be 0.39-0.708 L/h/kg (6.5 to 11.8 ml/min/kg). Following oral administration, clearance was found to be 141.65 L/h (range 41.34 to 335.80 L/h). Haloperidol clearance after extravascular administration ranges from 0.9-1.5 l/h/kg, however this rate is reduced in poor metabolizers of C_YP2D6_ enzyme. Reduced CYP2D6 enzyme activity may result in increased concentrations of haloperidol. The inter-subject variability (coefficient of variation, %) in haloperidol clearance was estimated to be 44% in a population pharmacokinetic analysis in patients with schizophrenia. Genetic polymorphism of CYP2D6 has been demonstrated to be an important source of inter-patient variability in the pharmacokinetics of haloperidol and may affect therapeutic response and incidence of adverse effects.

Haloperidol is well absorbed from the gastrointestinal tract but first-pass hepatic metabolism decreases oral bioavailability to 40 to 75%. Serum concentration peaks 0.5 to 4 hours after an oral dose.

The apparent volume of distribution is about 20 L/kg, consistent with the high lipophilicity of the drug. Haloperidol circulates in blood bound predominantly (90-94%) to plasma proteins.

Following administration of haloperidol in animals, the drug is distributed mainly into the liver, with lower concentrations being distributed into the brain, lung, kidneys, spleen, and heart. ... Haloperidol is about 92% bound to plasma proteins.

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Metabolism / Metabolites Haloperidol is extensively metabolised in the liver with only about 1% of the administered dose excreted unchanged in urine. In humans, haloperidol is biotransformed to various metabolites, including p-fluorobenzoylpropionic acid, 4-(4-chlorophenyl)-4-hydroxypiperidine, reduced haloperidol, pyridinium metabolites, and haloperidol glucuronide. In psychiatric patients treated regularly with haloperidol, the concentration of haloperidol glucuronide in plasma is the highest among the metabolites, followed, in rank order, by unchanged haloperidol, reduced haloperidol and reduced haloperidol glucuronide. The drug is thought to be metabolized primarily by oxidative N-dealkylation of the piperidine nitrogen to form fluorophenylcarbonic acids and piperidine metabolites (which appear to be inactive), and by reduction of the butyrophenone carbonyl to the carbinol, forming _hydroxyhaloperidol_. The enzymes involved in the biotransformation of haloperidol include cytochrome P450 (CYP) including CYP3A4 and CYP2D6, carbonyl reductase and uridine di-phosphoglucose glucuronosyltransferase enzymes. The greatest proportion of the intrinsic hepatic clearance of haloperidol is performed by glucuronidation and followed by the reduction of haloperidol to reduced haloperidol and by CYP-mediated oxidation. In studies of cytochrome-mediated disposition in vitro, CYP3A4 appears to be the major isoform of the enzyme responsible for the metabolism of haloperidol in humans. The intrinsic clearance of the back-oxidation of reduced haloperidol to the parent compound, oxidative N-dealkylation and pyridinium formation are of the same order of magnitude. This suggests that the same enzyme system is responsible for the above three metabolic reactions. In vivo human studies on haloperidol metabolism have shown that the glucuronidation of haloperidol accounts for 50 to 60% of haloperidol biotransformation and that approximately 23% of the biotransformation was accounted for by the reduction pathway. The remaining 20 to 30% ofthe biotransformation of haloperidol would be via N-dealkylation and pyridinium formation.

Although the exact metabolic fate has not been clearly established, it appears that haloperidol is principally metabolized in the liver. The drug appears to be metabolized principally by oxidative N-dealkylation of the piperidine nitrogen to form fluorophenylcarbonic acids and piperidine metabolites (which appear to be inactive), and by reduction of the butyrophenone carbonyl to the carbinol, forming hydroxyhaloperidol. Limited data suggest that the reduced metabolite, hydroxyhaloperidol, has some pharmacologic activity, although its activity appears to be less than that of haloperidol. Urinary metabolites in rats include p-fluorophenaceturic acid, beta-p-fluorobenzoylpropionic acid, and several unidentified acids.

... it is metabolized via reduction to reduced haloperidol, which is biologically inactive. Different extents of enterohepatic recycling, and ethnic differences in metabolism, could also account for the observed variability in haloperidol disposition. PMID:2689040

The enzymes involved in the biotransformation of haloperidol include cytochrome P450 (CYP), carbonyl reductase and uridine diphosphoglucose glucuronosyltransferase. The greatest proportion of the intrinsic hepatic clearance of haloperidol is by glucuronidation, followed by the reduction of haloperidol to reduced haloperidol and by CYP-mediated oxidation. In studies of CYP-mediated disposition in vitro, CYP3A4 appears to be the major isoform responsible for the metabolism of haloperidol in humans. The intrinsic clearances of the back-oxidation of reduced haloperidol to the parent compound, oxidative N-dealkylation and pyridinium formation are of the same order of magnitude, suggesting that the same enzyme system is responsible for the 3 reactions. Large variation in the catalytic activity was observed in the CYP-mediated reactions, whereas there appeared to be only small variations in the glucuronidation and carbonyl reduction pathways. Haloperidol is a substrate of CYP3A4 and an inhibitor, as well as a stimulator, of CYP2D6. PMID:10628896

... In vivo pharmacogenetic studies have indicated that the metabolism and disposition of haloperidol may be regulated by genetically determined polymorphic CYP2D6 activity. However, these findings appear to contradict those from studies in vitro with human liver microsomes and from studies of drug interactions in vivo. Interethnic and pharmacogenetic differences in haloperidol metabolism may explain these observations. PMID:10628896

Haloperidol has known human metabolites that include Haloperidol pyridinium, (2S,3S,4S,5R)-6-[4-(4-Chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]piperidin-4-yl]oxy-3,4,5-trihydroxyoxane-2-carboxylic acid, and p-Fluorobenzoylpropionic acid and 4-(4-chlorophenyl)-4-hydroxypiperidine. Haloperidol is a known human metabolite of reduced_haloperidol.

Haloperidol is well absorbed from the gastrointestinal tract but first-pass hepatic metabolism decreases oral bioavailability to 40 to 75%. Serum concentration peaks 0.5 to 4 hours after an oral dose. Following administration of haloperidol, the drug is distributed mainly into the liver, with lower concentrations being distributed into the brain, lung, kidneys, spleen, and heart. Although the exact metabolic fate has not been clearly established, it appears that haloperidol is principally metabolized in the liver. The drug appears to be metabolized principally by oxidative N-dealkylation of the piperidine nitrogen to form fluorophenylcarbonic acids and piperidine metabolites (which appear to be inactive), and by reduction of the butyrophenone carbonyl to the carbinol, forming hydroxyhaloperidol. Limited data suggest that the reduced metabolite, hydroxyhaloperidol, has some pharmacologic activity, although its activity appears to be less than that of haloperidol. Urinary metabolites include p-fluorophenaceturic acid, beta-p-fluorobenzoylpropionic acid, and several unidentified acids (A637, A566, A637). Half Life: 3 weeks

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Biological Half-Life
Following oral administration, the half-life was found to be 14.5-36.7 hours. Following intramuscular injection, mean half-life was found to be 20.7 hours.

10 MG Haloperidol IV and oral administration to healthy volunteers: serum T1/2 10-19 hr after IV and 12-38.3 hr after oral administration. Bioavailability in the order of 60%; distribution volume around 1300 L. PMID:822989

Haloperidol, Elimination: Oral: 24 hours (range 12 to 37 hours). Intramuscular: 21 hours (range, 17 to 25 hours). Intravenous: 14 hours (range, 10 to 19 hours). Haloperidol decanoate, Elimination: Approximately 3 weeks (single or multiple doses).

Toxicity Summary
IDENTIFICATION: Haloperidol is an antipsychotic agent. Haloperidol is a synthetic product. Haloperidol is the first of the butyrophenone series of major tranquillizers. Haloperidol is indicated for use in the management of manifestations of psychotic disorders such as schizophrenia and mania. It is indicated for the control of tics and vocal utterances of Tourette's Disorder in children and adults. It is effective for the treatment of severe behaviour problems in children of combative, explosive hyperexcitability. It is also used in the management of Gilles de La Tourette's syndrome, intractable hiccup and as an anti-emetic. HUMAN EXPOSURE: Main risks and target organs: The main features of severe overdosage are extrapyramidal reactions, hypotension, respiratory difficulty and impairment of consciousness. Haloperidol acts mainly as a dopamine antagonist. Summary of clinical effects: Consciousness may be depressed, progressing to coma; paradoxically, some patients manifest confusion, excitement and restlessness. Tremor or muscle twitching, muscle spasm, rigidity and convulsions are seen. Extrapyramidal signs can include dystonia, sometimes severe enough to impair swallowing or breathing; torticollis, oculogyric crises and opisthotonos. The pupils may be constricted or dilated. Hypotension and tachycardia are common. Sometimes there can be cardiac arrhythmias, including ventricular fibrillation, conduction defects and cardiac arrest. Contraindications: Severe dystonic reactions have followed the use of haloperidol, particularly in children and adolescents. It should therefore be used with extreme care in children. Haloperidol may also cause severe neurotoxic reactions in patients with hyperthyroidism and in patients receiving lithium. Haloperidol is contraindicated in severe toxic central nervous system depression or comatose states from any cause and individuals who are hypersensitive to this drug or have Parkinson's disease. Also contraindicated in late pregnancy because of dystonic reaction in the neonate. Infants should not be nursed during drug treatment. Routes of entry: Oral: It is the main route of administration. Parenteral: Through intravenous and intramuscular injection. Absorption by route of exposure: Haloperidol is readily absorbed from the gastrointestinal tract. Owing to the first-pass effect of metabolism in the liver, plasma concentrations following oral administration are lower than those following intramuscular administration. There is wide intersubject variation in plasma concentration of haloperidol and its therapeutic effects. The decanoate ester of haloperidol is very slowly absorbed from the site of injection and is therefore suitable for depot injection. It is gradually released into the bloodstream where it is rapidly hydrolysed to haloperidol. Distribution by route of exposure: Haloperidol is very extensively bound to plasma proteins (90%). It is widely distributed in body and crosses the bloodbrain barrier. Biological half-life by route of exposure: The plasma half-life in therapeutic doses is reported to range from about 13 to nearly 40 hours (Reynolds, 1989), with a mean of 20 hours. Metabolism: Haloperidol is metabolized in the liver and the paths of metabolism include oxidative N-dealkylation. Elimination by route of exposure: This rate of total systemic clearance increases in children and decreases in aged patients. After metabolism, haloperidol is excreted in the urine, via the bile and in the feces, there is evidence of enterohepatic recycling by 40%. About 26% was excreted in the urine by the healthy subjects and 20% by the patients in the first 5 days; by the third day about 15% had been excreted in the feces. It takes 28 days to fully eliminate a single oral dose. Mode of action: Pharmacodynamics: Dopamine receptors currently are classified as D-1(stimulate adenylate cyclase) and D-2(inhibit adenylate cyclase). Neuroleptic drugs block both D-1 and D-2 receptors but the significance of the ratio remains unclear. The therapeutic dose of neuroleptic drug appears to correlate with its affinity for brain dopamine D-2 receptors. Neuroleptic drugs also block a number of other receptors including H1 and H2 histamine, alfa 1 and alfa 2 adrenergic, muscarinic and serotoninergic receptors. Toxicity: Human data: Three cases of sudden death after taking 20 to 140 mg daily for one to four days. Children: A 29-month-old girl and an 11 month old boy who divided 265 mg of haloperidol between them developed lethargy, hypothermia, hyperreflexia, neuromuscular rigidity, unsteady gait and intention tremors. Although disturbances such as galactorrhea, amenorrhea, gynaecomastia, and impotence have been reported, the clinical significance of elevated serum prolactin levels is unknown for most patients. There are no well controlled studies with haloperidol in pregnant women. There are reports, however, of cases of limb malformations observed following maternal use of haloperidol along with other drugs which have suspected teratogenic potential during the first trimester of pregnancy. Causal relationships were not established in these cases. Since such experience does not exclude the possibility of fetal damage due to haloperidol; this drug should be used during pregnancy or in women likely to become pregnant only if the benefit clearly justifies a potential risk to the fetus. Interactions: The use of alcohol with this drug should be avoided due to possible additive effects and hypotension. An encephalopathic syndrome (characterised by weakness, lethargy, fever, tremulousness and confusion, extrapyramidal symptoms, leucocytosis, elevated serum enzymes, BUN, and FBS) followed by irreversible brain damage has occurred in a few patients treated with lithium plus haloperidol. A casual relationship between these events and the concomitant administration of lithium and haloperidol has not been established; however, patients receiving such combination therapy should be monitored closely for early evidence of neurological toxicity and treatment discontinued promptly if such signs appear (Physician's Desk Reference, 1987). Other reported interactions involve the following drugs and adverse effects: Beta-blockers: Severe hypotension or pulmonary arrest. Methyldopa: Dementia, psychomotor retardation, memory impairment and inability to concentrate. Indomethacin: Severe drowsiness and confusion. Main adverse effects: In general, the symptoms of overdose would be an exaggeration of known pharmacological effects and adverse reactions. Anticholinergic side effects and sedation occur less often than with aliphatic phenothiazines, but extrapyramidal reactions are more common. Administration of antidopaminergic and anticholinergics may worsen or bring forward the onset of extrapyramidal effects. Idiosyncratic reaction producing severe drowsiness when used with indomethacin. ANIMAL/PLANT STUDIES: Carcinogenicity: Carcinogenicity studies using oral haloperidol were conducted in Wistar rats and in Albino Swiss mice. In the rat study, survival was less than optimal in all dose groups, reducing the number of rats at risk for developing tumors. However, although a relatively greater number of rats survived to the end of the study in high dose male and female groups, these animals did not have a greater incidence of tumors than control animals. Therefore, although not optimal, this study does suggest the absence of haloperidol related increase in the incidence of neoplasia in rats. In female mice there was a statistically significant increase in mammary gland neoplasia and total tumor incidence; there was a statistically significant increase in pituitary gland neoplasia. In male mice, no statistically significant differences in incidence of total tumors or specific tumor types were noted. Neuroleptic drugs elevate prolactin levels; the elevation persists during chronic administration. Teratogenicity: Rodents haloperidol by oral or parenteral routes showed an increase in incidence of resorption, reduced fertility, delayed delivery and pup mortality. No teratogenic effect has been reported in rats, rabbits or dogs at dosages within this range, but cleft palate has been observed in mice. Mutagenicity: No mutagenic potential of haloperidol was found in the Ames Salmonella microsomal activation assay.

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The precise mechanism whereby the therapeutic effects of haloperidol are produced is not known, but the drug appears to depress the CNS at the subcortical level of the brain, midbrain, and brain stem reticular formation. Haloperidol seems to inhibit the ascending reticular activating system of the brain stem (possibly through the caudate nucleus), thereby interrupting the impulse between the diencephalon and the cortex. The drug may antagonize the actions of glutamic acid within the extrapyramidal system, and inhibitions of catecholamine receptors may also contribute to haloperidol's mechanism of action. Haloperidol may also inhibit the reuptake of various neurotransmitters in the midbrain, and appears to have a strong central antidopaminergic and weak central anticholinergic activity. The drug produces catalepsy and inhibits spontaneous motor activity and conditioned avoidance behaviours in animals. The exact mechanism of antiemetic action of haloperidol has also not been fully determined, but the drug has been shown to directly affect the chemoreceptor trigger zone (CTZ) through the blocking of dopamine receptors in the CTZ.

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Hepatotoxicity
Liver test abnormalities have been reported to occur in 20% of patients on long term therapy with haloperidol, but elevations are uncommonly above 3 times the upper limit of normal. The aminotransferase abnormalities are usually mild, asymptomatic and transient, reversing even with continuation of medication. Instances of clinically apparent acute liver injury have been reported due to haloperidol, but they are uncommon. The onset of jaundice is within 2 to 6 weeks, and the pattern of serum enzyme elevations is typically cholestatic or mixed. Signs of hypersensitivity (fever, rash and eosinophilia) have been reported in some cases, but they are usually mild and self-limited; autoantibodies are rare.
Likelihood score: B (likely cause of clinically apparent liver injury).

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Health Effects
Tachycardia, hypotension, and hypertension; Extrapyramidal Symptoms (EPS) such as akathisia, or dystonia; impaired liver function and/or jaundice have been reported. Maculopapular and acneiform skin reactions and isolated cases of photosensitivity and loss of hair.Laryngospasm, bronchospasm, cataracts, retinopathy and visual disturbances; lactation, breast engorgement, mastalgia, menstrual irregularities, gynecomastia, impotence, increased libido, hyperglycemia, hypoglycemia and hyponatremia (RxList, A308).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Limited information indicates that maternal doses of haloperidol up to 10 mg daily produce low levels in milk and usually do not affect the breastfed infant. Very limited long-term follow-up data indicate no adverse developmental effects when haloperidol is used alone. However, use with other antipsychotic drugs occasionally might negatively affect the infant. One expert guideline recommends against using haloperidol during breastfeeding, but a safety scoring system finds haloperidol possible to use cautiously during breastfeeding. Monitor the infant for drowsiness and developmental milestones, especially if other antipsychotics are used concurrently.

◉ Effects in Breastfed Infants
In one breast-fed infant, there were no sedative effects and the baby fed well during maternal intake of 5 mg orally twice daily. The mother took haloperidol during six weeks of breast feeding and at 6 and 12 months of age, the baby had achieved all milestones of growth and development.
One infant was breastfed for 5 weeks beginning at 2 weeks of age during maternal haloperidol (dose not stated) and imipramine (150 mg daily) therapy. The infant showed normal development when tested once between 1 and 4 months and once between 12 and 18 months of age.
In a small prospective study on the long-term effects of antipsychotics in breastfed infants, a decline in developmental scores was found at 12 to 18 months of age in 2 of the 4 the infants of mothers taking both chlorpromazine and haloperidol. The other 2 infants and all infants exposed to either drug alone developed normally.
One woman with schizophrenia took haloperidol and trihexyphenidyl during 3 pregnancies and postpartum. Haloperidol doses were 7.5 to 10 mg daily in the first 2 pregnancies and 15 mg daily in the third. She breastfed (extent not stated) all 3 children for 6 to 8 months using the same doses. Development was age-appropriate in all children aged 16 months at 8 years of age at the time of assessment.
Two women, one with bipolar disorder and the other with long-standing schizophrenia, were treated with haloperidol 5 mg daily during pregnancy and breastfeeding (extent not stated). One mother also received olanzapine 10 mg daily and the other received amisulpride 400 mg daily. Follow-up of the breastfed infants for 11 to 13 months found no adverse effects and normal development of the infants.
A woman diagnosed with schizophrenia was taking risperidone 1.5 mg daily during late pregnancy and postpartum while nursing (extent not stated) her full-term infant. At 2 weeks postpartum, haloperidol 0.8 mg daily was added because of a recurrence of symptoms. At these dosages, no adverse effects were seen in the infant. However, because of recurring symptoms, the dosage of haloperidol was increased to 1.5 mg daily. Three days later, the infant had excessive sedation, poor feeding, and slowing in motor movements. Pediatric assessment found no medical reason for these effects. Breastfeeding was discontinued and the infant's symptoms resolved completely in 5 days. The infant's symptoms were probably caused by the drug combination.

◉ Effects on Lactation and Breastmilk
Galactorrhea caused by hyperprolactinemia has been reported with haloperidol The hyperprolactinemia is caused by the drug's dopamine-blocking action in the tuberoinfundibular pathway. The maternal prolactin level in a mother with established lactation may not affect her ability to breastfeed.

Drugs and Lactation Database (LactMed) ◈ What is haloperidol?
Haloperidol is a medication that has been used to treat schizophrenia and other mental health conditions. It has also been used to treat a severe type of nausea and vomiting during pregnancy (hyperemesis gravidarum). More information on nausea and vomiting in pregnancy can be found here: https://mothertobaby.org/fact-sheets/nausea-vomiting-pregnancy-nvp/. A brand name for haloperidol is Haldol®.Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take this medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.

◈ I take haloperidol. Can it make it harder for me to get pregnant?
Based on the studies reviewed, haloperidol may cause a higher level of prolactin (a hormone that helps the body make milk) in the blood than is usual. This is called hyperprolactinemia. Hyperprolactinemia may make it harder to get pregnant.

◈ Does taking haloperidol increase the chance for miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not been done in humans to see if haloperidol increases the chance for miscarriage. Based on animal studies, haloperidol is not expected to increase the chance for miscarriage.

◈ Does taking haloperidol increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Based on the studies reviewed, haloperidol is not expected to increase the chance for birth defects above the background risk. Most studies looking at the use of haloperidol during pregnancy did not find an increased chance for birth defects. There are two case reports of limb defects in infants after exposure to haloperidol and other medications during pregnancy. One study looking at 188 pregnancies exposed to haloperidol found no increased chance for birth defects. In this study, limb defects were reported in one infant. It is not known if haloperidol, other medications, or other factors caused the limb defects.

◈ Does taking haloperidol in pregnancy increase the chance of other pregnancy-related problems?
Based on the studies reviewed, haloperidol is not expected to increase the chance of other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). One study reported an increase in preterm delivery and lower birth weights when haloperidol was taken during pregnancy. However, the authors of the study reported they did not have information on some important factors that could be linked to low birth weight and/or preterm delivery. It is not known if haloperidol, other medications, or other factors increased the chance for these problems.

◈ I need to take haloperidol throughout my entire pregnancy. Will it cause withdrawal symptoms in my baby after birth?
There have been reports of withdrawal symptoms in newborns exposed to haloperidol during pregnancy. Symptoms might include low muscle tone (floppy), restlessness, unusual sleep patterns, trouble eating, involuntary shaking movements (tremors), and dehydration. Not all babies exposed to haloperidol will have these symptoms. It is important that your healthcare providers know you are taking haloperidol so that if symptoms occur your baby can get the care that is best for them.

◈ Does taking haloperidol in pregnancy affect future behavior or learning for the child?
Based on the studies reviewed, it is not known if haloperidol increases the chance for behavior or learning issues.

◈ Breastfeeding while taking haloperidol:
Information on the use of haloperidol while breastfeeding is limited. Haloperidol passes into breastmilk. Most breastfed babies exposed to haloperidol have no reported symptoms.One breastfeeding infant reportedly had trouble with feeding, being too sleepy, and slow movements after exposure to haloperidol and risperidone through breastmilk. The baby’s symptoms went away after breastfeeding was stopped. The reported symptoms may be related to the combination of medications. If you suspect the baby has any symptoms (such as drowsiness), contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all of your breastfeeding questions.

◈ If a male takes haloperidol, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
Males who take haloperidol may develop hyperprolactinemia, which can cause problems with sexual desire or the ability to have an orgasm. Studies have not been done to see if haloperidol use by males could increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.A pregnancy registry for psychiatric medications, including this one, has been organized at the Massachusetts General Hospital. Contact the registry at https://womensmentalhealth.org/clinical-and-research-programs/pregnancyregistry/.

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Exposure Routes Inhalation, Oral (60%)

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Symptoms LD₅₀=165 mg/kg (rats, oral) Toxicity Data LD50: 128 mg/kg (Oral, Rat) LD50: 71 mg/kg (Oral, Mouse) LD50: 90 mg/kg (Oral, Dog) LD50: 165 mg/kg (Oral, Rat)

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Treatment
Since there is no specific antidote, treatment is primarily supportive. A patent airway must be established by use of an oropharyngeal airway or endotracheal tube or, in prolonged cases of coma, by tracheostomy. Respiratory depression may be counteracted by artificial respiration and mechanical respirators. Hypotension and circulatory collapse may be counteracted by use of intravenous fluids, plasma, or concentrated albumin, and vasopressor agents such as metaraminol, phenylephrine and norepinephrine. Epinephrine should not be used. In case of severe extrapyramidal reactions, anti-Parkinson medication should be administered. ECG and vital signs should be monitored especially for signs of Q-T prolongation or dysrhythmias and monitoring should continue until the ECG is normal. Severe arrhythmias should be treated with appropriate anti-arrhythmic measures. (L1712)

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Non-Human Toxicity Values
LD50 Rat oral 165 mg/kg

LD50 Mouse ip 60 mg/kg

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Protein Binding
Studies have found that free fraction of haloperidol in human plasma is 7.5-11.6%. This was found to be comparable among healthy adults, young adults, elderly patients with schizophrenia, and even in patients with liver cirrhosis.

[1].Froemming JS, et al. Pharmacokinetics of haloperidol. Clin Pharmacokinet. 1989 Dec;17(6):396-423.

[2].Shapiro AK, et al. Treatment of Gilles de la Tourette's Syndrome with haloperidol. Br J Psychiatry. 1968 Mar;114(508):345-50.

See also: Haloperidol (broader).

C24H29CLFNO5

465.942169904709

465.172

53515-91-6

Haloperidol;52-86-8;Haloperidol-d4;1189986-59-1;Haloperidol-d4-1;136765-35-0;Haloperidol hydrochloride;1511-16-6

16051968

Typically exists as solid at room temperature

3.815

3

7

7

32

510

0

ClC1C=CC(=CC=1)C1(CCN(CCCC(C2C=CC(=CC=2)F)=O)CC1)O.OC(C(=O)O)C

BVUSNQJCSYDJJG-UHFFFAOYSA-N

InChI=1S/C21H23ClFNO2.C3H6O3/c22-18-7-5-17(6-8-18)21(26)11-14-24(15-12-21)13-1-2-20(25)16-3-9-19(23)10-4-16;1-2(4)3(5)6/h3-10,26H,1-2,11-15H2;2,4H,1H3,(H,5,6)

4-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]-1-(4-fluorophenyl)butan-1-one;2-hydroxypropanoic acid

Haloperidol lactate; Haloperidol Intensol; 53515-91-6; Haloperidol lactate (salt); UNII-6387S86PK3; Haloperidol lactate [Orange Book]; 6387S86PK3; Haloperidol (lactate);

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)