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Haloperidol, 1.5 mg tablets

Drug formTablets

ATC categoryNeurology. Psychiatry

ATC subcategoryNeuroleptics

Brand nameHaloperidol

Generic nameHaloperidol

Composition

Each tablet of Haloperidol 1.5 mg contains:

active ingredient: haloperidol – 1.5 mg;

excipients: microcrystalline cellulose, talc purified, maize (corn) starch, lactose monohydrate, povidone, sodium starch glycolate, magnesium stearate.

Pharmacological group and ATC code
Antipsychotics; N05AD01.

Chemical name and CAS number
4-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]-1-(4-fluorophenyl)butan-1-one;
52-86-8.

Pharmacology

Haloperidol is a butyrophenone with general properties similar to those of the phenothiazine, chlorpromazine. It is an antipsychotic with actions most closely resembling those of phenothiazines with a piperazine side-chain.

Haloperidol acts as a central and peripheral dopamine receptor antagonist. It also has some anticholinergic activity and binds to opiate receptors.

Pharmacokinetics

Haloperidol is readily absorbed from the gastrointestinal tract. It is metabolised in the liver and is excreted in the urine and, via the bile, in the faeces; there is evidence of enterohepatic recycling. Owing to first-pass metabolism in the liver, plasma concentrations after oral doses are lower than those after intramuscular injection. Moreover, there is wide intersubject variation in plasma concentrations of haloperidol. In practice, however, no strong correlation has been found between plasma concentrations of haloperidol and its therapeutic effect. Paths of metabolism of haloperidol include oxidative N-dealkylation and reduction of the ketone group to form an alcohol known as reduced haloperidol. Haloperidol has been reported to have a plasma elimination half-life ranging from about 12 to 38 hours after oral doses. Haloperidol is about 92% bound to plasma proteins. It is widely distributed in the body and crosses the blood-brain barrier. Haloperidol is distributed into breast milk.

Uses and administration
Haloperidol is used in the treatment of various psychoses including schizophrenia and mania, and in behaviour disturbances, in Tourette’s syndrome and severe tics, in intractable hiccups, and in severe anxiety, including for the sedation of patients in intensive care or palliative care.

Adminsitration

Haloperidol is given by mouth.

Dosages should be reduced in elderly or debilitated patients; a usual starting dose is half the normal adult dose. Doses at the lower end of the scale are also advised for adolescents.

Schizophrenia and other psychoses, mania, short-term adjunctive management of psychomotor agitation, excitement, and violent or dangerously impulsive behaviour,by mouth, initially 1.5–3 mg 2–3 times daily or 3–5 mg 2–3 times daily in severely affected or resistant patients; in resistant schizophrenia up to 30 mg daily may be needed; adjusted according to response to lowest effective maintenance dose (as low as 5–10 mg daily); elderly (or debilitated) initially half adult dose; childinitially 25–50 micrograms/kg daily (in 2 divided doses) to max. 10 mg.

Intractable hiccup, by mouth, 1.5 mg 3 times daily adjusted according to response; child not recommended.

Adverse effects

Haloperidol is less likely to cause sedation, hypotension, or antimuscarinic effects, but is associated with a higher incidence of extrapyramidal effects. Haloperidol should be used with great care in children and adolescents as they may be at increased risk of severe dystonic reactions; patients with hyperthyroidism may also be at increased risk.

Haloperidol may cause adverse effects such as dry mouth, constipation, difficulty with micturition, blurred vision, and mydriasis. Tachycardia, ECG changes (particularly Q-and T-wave abnormalities), and, rarely, cardiac arrhythmias may occur; hypotension (usually orthostatic) is common. Other adverse effects include delirium, agitation and, rarely, catatonic-like states, insomnia or drowsiness, nightmares, depression, miosis, EEG changes and convulsions, nasal congestion, minor abnormalities in liver function tests, inhibition of ejaculation, impotence, and priapism.

Hypersensitivity reactions include urticaria, exfoliative dermatitis, erythema multiforme. A syndrome resembling systemic lupus erythematosus has been reported. Jaundice has occurred, and probably has an immunological origin. Prolonged therapy may lead to deposition of pigment in the skin, or more frequently the eyes; corneal and lens opacities have been observed.

Haematological disorders, including haemolytic anaemia, aplastic anaemia, thrombocytopenic purpura, eosinophilia, and a potentially fatal agranulocytosis have occasionally been reported. Mild leucopenia has been stated to occur in up to 30% of patients on prolonged high dosage.

Extrapyramidal dysfunction and resultant disorders include acute dystonia, a parkinsonism-like syndrome, and akathisia; late effects include tardive dyskinesia and perioral tremor. The neuroleptic malignant syndrome may also occur.

Haloperidol alters endocrine and metabolic functions. Patients have experienced amenorrhoea, galactorrhoea, and gynaecomastia due to hyperprolactinaemia, weight gain, and hyperglycaemia and altered glucose tolerance. Body temperature regulation is impaired and may result in hypo- or hyperthermia depending on environment. There have also been reports of hypercholesterolaemia.

Withdrawal symptoms have been seen on abrupt withdrawal in patients receiving prolonged and/or high-dose maintenance therapy.

Effects on ability to drive and use machines
– Some degree of sedation or impairment of alertness may occur, particularly with higher doses and at the start of treatment, and may be potentiated by alcohol or other CNS depressants. Patients should be advised not to undertake activities requiring alertness such as driving or operating machinery during treatment, until their susceptibility is known.

Contraindications
Antipsychotic drugs may be contra-indicated in comatose states, CNS depression, bone-marrow suppression, phaeochromocytoma, or prolactin-dependent tumours. Haloperidol is contraindicated during pregnancy, and it is advisable to discontinue breast-feeding during treatment.

Precautions

Antipsychotics should be used with caution or not at all in patients with impaired liver, kidney, cardiovascular, cerebrovascular, and respiratory function and in those with angle-closure glaucoma, a history of jaundice, parkinsonism, diabetes mellitus, hypothyroidism, myasthenia gravis, paralytic ileus, prostatic hyperplasia, or urinary retention. Care is required in patients with epilepsy or a history of seizures as antipsychotics may lower the seizure threshold. Debilitated patients may be more prone to the adverse effects of аntipsychotics as may the elderly, especially those with dementia.

The sedative effects of аntipsychotics are most marked in the first few days of treatment; affected patients should not drive or operate machinery.

The effects of аntipsychotics on the vomiting centre may mask the symptoms of overdosage of other drugs, or of disorders such as gastrointestinal obstruction. Use at extremes of temperature may be hazardous since body temperature regulation is impaired by аntipsychotics.

Regular eye examinations are advisable for patients receiving long-term haloperidol therapy and avoidance of undue exposure to direct sunlight is recommended. Antipsychotics should be used with caution in the presence of acute infection or leucopenia. Blood counts are advised if the patient develops an unexplained infection or fever.

Haloperidol should be used with caution subarachnoid haemorrhage and metabolic disturbances such as hypokalaemia, hypocalcaemia, or hypomagnesaemia.

Abrupt withdrawal of phenothiazine therapy is best avoided.

Overdosage

Symptoms

In general, the manifestations of haloperidol overdosage are an extension of its pharmacological actions, the most prominent of which would be severe extrapyramidal symptoms, hypotension and psychic indifference with a transition to sleep. The risk of ventricular arrhythmias possibly associated with QT-prolongation should be considered. The patient may appear comatose with respiratory depression and hypotension which could be severe enough to produce a shock-like state. Paradoxically hypertension rather than hypotension may occur. Convulsions may also occur.

Treatment

There is no specific antidote to haloperidol. A patent airway should be established and maintained with mechanically assisted ventilation if necessary. In view of isolated reports of arrhythmia ECG monitoring is strongly advised. Hypotension and circulatory collapse should be treated by plasma volume expansion and other appropriate measures. Adrenaline should not be used. The patient should be monitored carefully for 24 hours or longer, body temperature and adequate fluid intake should be maintained.

In cases of severe extrapyramidal symptoms, appropriate anti-Parkinsonian medication should be administered.

Drug interactions

Haloperidol must be used with extreme caution in patients receiving lithium; an encephalopathic syndrome has been reported after their use together.

In common with all neuroleptics, haloperidol can increase the central nervous system depression produced by other CNS-depressant drugs, including alcohol, hypnotics, sedatives or strong analgesics.

An enhanced CNS effect, when combined with methyldopa, has been reported.

Haloperidol may antagonise the action of adrenaline and other sympathomimetic agents and reverses the blood pressure lowering effects of adrenergic-blocking agents such as guanethidine.

The dosage of anticonvulsants may need to be increased to take account of the lowered seizure threshold.

Co-administration of enzyme-inducing drugs such as carbamazepine, phenobarbital and rifampicin with haloperidol may result in a significant reduction of haloperidol plasma levels. The haloperidol dose may therefore need to be increased, according to the patient’s response. After stopping such drugs, it may be necessary to readjust the dosage of haloperidol.

Haloperidol may impair the metabolism of tricyclic antidepressants (clinical significance unknown) and the anti-Parkinson effects of levodopa.

In pharmacokinetic studies, increased haloperidol levels have been reported when haloperidol was given concomitantly with the following drugs: quinidine, buspirone and fluoxetine. Haloperidol plasma levels should therefore be monitored and reduced if necessary. Metabolic inhibitors of cytochrome P450, and specifically CYP2D6 may increase haloperidol levels.

Use of haloperidol with concomitant QT prolonging drugs may result in additional QT prolongation and is not recommended (please refer to Section 4.3 – Contraindications). Use of drugs that cause electrolyte imbalance may increase the risk of ventricular arrhythmias during concomitant use of haloperidol.

Antagonism of the effect of phenindione has been reported.

In rare cases, an encephalopathy-like syndrome has been reported in combination with lithium and haloperidol. It remains controversial whether these cases represent a distinct clinical entity or whether they are in fact cases of NMS and/or lithium toxicity. Signs of encephalopathy-like syndrome include confusion, disorientation, headache, disturbances of balance and drowsiness. One report showing symptomless EEG abnormalities on the combination has suggested that EEG monitoring might be advisable. When lithium and haloperidol therapy are used concomitantly, haloperidol should be given in the lowest effective dosage and lithium levels should be monitored and kept below 1 mmol/l. If symptoms of encephalopathy-like syndrome occur, therapy should be stopped immediately.

Identification

White or off white scored cylindrical tablets with a few small darker spots.

Presentation

48 tablets (2 blister packets with 24 tablets in the cardboard box).

Expiry date

3 years. Do not use after the expiration date.

Prescription status

To be dispensed with prescription.

Storage conditions

Store at a room temperature (15-250C), in a dry place, out of the reach of children. Protect from light.