Butyrophenones (antipsychotics).

Benperidol

White tablets, containing 0.25mg benperidol.

Tablets

For the control of deviant anti-social sexual behaviour.

Route of administration - Oral.

Adults

0.25mg/day to 1.5mg/day in divided doses. Dosage is best initiated and adjusted under close clinical supervision as individual response to neuroleptic drugs is variable.

In determining dosage, consideration should be given to the patient's age, severity of symptoms and previous response to other neuroleptic drugs.

Patients who are debilitated, or those with previously reported adverse reactions to neuroleptic drugs, may require less Anquil, and half the normal starting dose may be sufficient for therapeutic response.

In adolescents, a lower dose may be advisable.

Not recommended.

Half the normal starting dose may be sufficient for therapeutic response.

Comatose states, patients with extrapyramidal symptoms, CNS depression, hypersensitivity to any of the ingredients of Anquil or other butyrophenones, depressive disorders or Parkinson's disease.

Rare cases of sudden and unexplained death have been reported in psychiatric patients receiving antipsychotic drugs. However, Anquil has not been clearly implicated in any case.

Acute withdrawal symptoms, including nausea, vomiting and insomnia, have very rarely been described after abrupt cessation of high doses of antipsychotic drugs. Relapse may also occur and gradual withdrawal is advisable.

Where prolonged treatment with Anquil is envisaged, it would be a reasonable precaution to carry out regular blood counts and tests of liver function.

Caution is advised in patients with liver disease, renal failure, cardiovascular disease, epilepsy, and conditions predisposing to epilepsy and convulsions.

As with other neuroleptics, cases of QT interval prolongation may occur. Consequently, and if the clinical situation permits, absence of the following risk factors for onset of this type of arrhythmia should be verified prior to administration:

• Cardiac disease.

• A family history of sudden death and/or QT prolongation.

• Uncorrected electrolyte disturbances.

• A history of QT interval prolongation, ventricular arrhythmias or Torsades de Pointes.

Prior to initiation of treatment with Anquil, it may be appropriate to consider an ECG with measurement of serum calcium, magnesium and potassium levels. This is especially important in the elderly and patients with a positive personal or family history of cardiac disease or abnormal findings on cardiac clinical examination. During therapy, periodic serum electrolyte levels may be monitored and corrected if necessary, especially during long-term usage; if concomitant diuretics are taken; or during inter-current illness. Concomitant neuroleptics should be avoided.

An ECG may be appropriate to assess the QT interval whenever dose escalation is proposed and when the maximum therapeutic dose is reached. The dose of Anquil should be reduced if the QT interval is prolonged and discontinued if the QTc interval is greater than 500ms.

An approximately 3-fold increased risk of cerebrovascular adverse events has been seen in randomised placebo controlled clinical trials in the dementia population with some atypical antipsychotics. The mechanism for this increased risk is not known. An increased risk cannot be excluded for other antipsychotics or other patient populations. Benperidol should be used with caution in patients with risk factors for stroke.

Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine as it contains lactose.

In common with all neuroleptics, Anquil can increase the CNS depression produced by other CNS-depressant drugs, including alcohol, hypnotics, sedatives, strong analgesics or sedating antihistamines and may antagonise the action of adrenaline (epinephrine) and other sympathomimetic agents.

Certain agents (e.g. phenobarbital, carbamazepine, phenytoin, rifampicin, primidone), as well as smoking and alcohol consumption, which stimulate metabolising enzymes in the liver, may theoretically enhance the metabolic breakdown of neuroleptics, necessitating an increased dose. Fluoxetine, buspirone and ritonavir may cause an increase in the plasma concentration of Anquil necessitating a dose modification.

The effect of Anquil may be reduced by concomitant antimuscarinic medications.

Anquil may impair the anti-Parkinson effects of levodopa and other dopamine agonists. The dosage of anti-convulsants may need to be increased to take account of the lowered seizure threshold.

The use of Anquil with anticonvulsants such as barbiturates, carbamazepine, ethosuximide, oxcarbazepine, phenytoin, primidone and valproate may lower the seizure threshold, thereby necessitating a review of the anticonvulsant dose requirement.

The risk of hypotension with antihypertensive drugs, anaesthetics and opioid analgesics may be increased when Anquil is given concomitantly.

Enhanced CNS effects when combined with methyldopa have been reported for some butyrophenones.

Medicines that can prolong the QT interval should be avoided, as should any medicines that can cause electrolyte imbalance. In particular amiodarone and moxifloxacin should be avoided.

It is advised that Anquil should be avoided if artemether/lumefantrine is administered. Concomitant use of pramipexole or ropinirole with Anquil should be avoided as there may be antagonism of their effect.

The risk of extrapyramidal side effects is increased if amantadine, metoclopramide or tetrabenazine are used concomitantly with Anquil.

Concomitant treatment with lithium increases the risk of extrapyramidal side effects, and may cause neurotoxicity.

The effects of antipsychotics may be reduced by concomitant treatment with memantine.

The effect of sodium benzoate or sodium phenylbutyrate may be reduced by concomitant butyrophenones.

Central nervous system

In common with all neuroleptics, extrapyramidal symptoms may occur, e.g. tremor, rigidity, hypersalivation, bradykinesia, akathisia, acute dystonia, oculogyric crisis and laryngeal dystonia.

Anti-Parkinson agents should only be given as required; they should not be prescribed routinely as a preventive measure.

As with all antipsychotic agents, tardive dyskinesia may appear in some patients on long-term therapy or after drug discontinuation. The syndrome is mainly characterised by rhythmical involuntary movements of the tongue, face, mouth or jaw. The manifestations may be permanent in some patients. Anquil should be given in the minimal effective dose for the minimum possible time.

The syndrome may be masked when the treatment is reinstituted, when the dosage is increased or when a switch is made to a different antipsychotic drug. Treatment should be discontinued as soon as possible.

The potential seriousness and unpredictability of tardive dyskinesia and the fact that it has occasionally been reported to occur when neuroleptic antipsychotic drugs have been prescribed for relatively short periods in low dosage means that the prescribing of such agents requires especially careful assessment of risks versus benefit. Tardive dyskinesia can be precipitated or aggravated by anti-Parkinson drugs. Tardive dyskinesia may occur after abrupt drug withdrawal.

It has been reported that fine vermicular movements of the tongue may be an early sign of tardive dyskinesia and that the full syndrome may not develop if the medication is stopped at that time. If signs and symptoms of tardive dyskinesia appear, the discontinuation of all neuroleptic drugs should be considered.

As with other neuroleptics, rare cases of neuroleptic malignant syndrome, an idiosyncratic response characterised by hyperthermia, generalised muscle rigidity, autonomic instability, altered consciousness, coma and elevated CPK levels, have been reported. Signs of autonomic dysfunction such as tachycardia, labile arterial pressure and sweating may precede the onset of hyperthermia, acting as early warning signs. Antipsychotic treatment should be withdrawn immediately and appropriate supportive therapy and careful monitoring instituted.

Anquil, even in low dosage in susceptible (especially non-psychotic) individuals, may cause unpleasant subjective feelings of being mentally dulled or slowed down, dizziness, headache, or paradoxical effects of excitement, agitation or insomnia.

Depression and seizures have been reported rarely. A causal relationship with Anquil has not been unequivocally established.

Confusional or agitated states have been reported rarely.

Gastro-intestinal system

Nausea, vomiting, loss of appetite, constipation and dyspepsia have been reported.

Endocrinological system

Hormonal effects of antipsychotic neuroleptic drugs include hyper-prolactinaemia, which may cause galactorrhoea, gynaecomastia and oligo- or amenorrhoea.

Cardiovascular system

Dose-related hypotension is uncommon but can occur, particularly in the elderly who are more susceptible to the sedative and hypotensive effects. Benign tachycardia has occasionally been reported.

As with other neuroleptics QT prolongation, ventricular arrhythmias (including ventricular fibrillation and rarely ventricular tachycardia), Torsades de Pointes and cardiac arrest may occur. In rare cases this may lead to sudden “unexplained” death. Treatment of undesirable cardiac effects includes withdrawal of the causal agent, and correction of hypoxia, electrolyte abnormalities and acid base disturbances.

Other adverse reactions

Jaundice or transient abnormalities of liver function in the absence of jaundice have been reported. The following effects have been reported rarely: oedema, skin rashes or hypersensitivity reactions such as exanthema and pruritus. Blood dyscrasias, including granulocytopenia, have been reported occasionally. Weight changes may occur. Isolated cases of salivation and body temperature dysregulation have been reported.

Concord

(POM)

04 June 2009