Etrafon-A - General Information
An antipsychotic phenothiazine derivative with actions and uses similar to those of chlorpromazine. [PubChem]
Pharmacology of Etrafon-A
Etrafon-A is a piperazinyl phenothiazine, acts on the central nervous system, and has a greater behavioral potency than other phenothiazine derivatives whose side chains do not contain a piperazine moiety. It is a member of a class of drugs called phenothiazines, which are dopamine D1/D2 receptor antagonists. Etrafon-A is 10 to 15 times as potent as chlorpromazine; that means perphenazine is a highly potent antipsychotic. In equivalent doses it has approximately the same frequency and severity of early and late extrapypramidal side-effects compared to Haloperidol.
Etrafon-A for patients
This information is intended to aid in the safe and effective use of this medication. It is not a disclosure of all possible adverse or intended effects.
Given the likelihood that a substantial proportion of patients exposed chronically to neuroleptics will develop tardive dyskinesia, it is advised that all patients in whom chronic use is contemplated be given, if possible, full information about this risk. The decision to inform patients and/or their guardians must obviously take into account the clinical circumstances and the competency of the patient to understand the information provided.
Metabolism of a number of medications, including antipsychotics, antidepressants, b- blockers, and antiarrhythmics, occurs through the cytochrome P450 2D6 isoenzyme (debrisoquine hydroxylase). Approximately 10% of the Caucasian population has reduced activity of this enzyme, so-called poorî metabolizers. Among other populations the prevalence is not known. Poor metabolizers demonstrate higher plasma concentrations of antipsychotic drugs at usual doses, which may correlate with emergence of side effects. In one study of 45 elderly patients suffering from dementia treated with perphenazine, the 5 patients who were prospectively identified as poor P450 2D6 metabolizers had reported significantly greater side effects during the first 10 days of treatment than the 40 extensive metabolizers, following which the groups tended to converge. Prospective phenotyping of elderly patients prior to antipsychotic treatment may identify those at risk for adverse events.
The concomitant administration of other drugs that inhibit the activity of P450 2D6 may acutely increase plasma concentrations of antipsychotics. Among these are tricyclic antidepressants and selective serotonin reuptake inhibitors, e.g.fluoxetine, sertraline and paroxetine. When prescribing these drugs to patients already receiving antipsychotic therapy, close monitoring is essential and dose reduction may become necessary to avoid toxicity. Lower doses than usually prescribed for either the antipsychotic or the other drug may be required.
An electrocardiogram should be taken and close monitoring of cardiac function instituted if there is any sign of abnormality. Cardiac arrhythmias may be treated with neostigmine, pyridostigmine, or propranolol. Digitalis should be considered for cardiac failure. Close monitoring of cardiac function is advisable for not less than five days. Vasopressors such as norepinephrine may be used to treat hypotension, but epinephrine should NOT be used.
Anticonvulsants (an inhalation anesthetic, diazepam, or paraldehyde) are recommended for control of convulsions, since perphenazine increases the central nervous system depressant action, but not the anticonvulsant action of barbiturates.
If acute parkinson-like symptoms result from perphenazine intoxication, benztropine mesylate or diphenhydramine may be administered.
Central nervous system depression may be treated with nonconvulsant doses of CNS stimulants. Avoid stimulants that may cause convulsions (e.g., picrotoxin and pentylenetetrazol).
Signs of arousal may not occur for 48 hours.
Dialysis is of no value because of low plasma concentrations of the drug.
Since overdosage is often deliberate, patients may attempt suicide by other means during the recovery phase. Deaths by deliberate or accidental overdosage have occurred with this class of drugs.
Additional information about Etrafon-A
Etrafon-A Indication: For use in the management of the manifestations of psychotic disorders and for the control of severe nausea and vomiting in adults.
Mechanism Of Action: Binds to the dopamine D1 and dopamine D2 receptors and inhibits their activity. The mechanism of the anti-emetic effect is due predominantly to blockage of the dopamine D2 neurotransmitter receptors in the chemoreceptor trigger zone and vomiting centre. Etrafon-A also binds the alpha andrenergic receptor. This receptor's action is mediated by association with G proteins that activate a phosphatidylinositol-calcium second messenger system.
Drug Interactions: Not Available
Food Interactions: Avoid alcohol.
Take with food.
Do not take calcium, aluminum, magnesium or Iron supplements within 2 hours of taking this medication.
Generic Name: Perphenazine
Synonyms: PZC; Perphenazin; Perfenazine; Perfenazina; Chlorperphenazine; Etaperazin; Etaperazine; Ethaperazine
Drug Category: Antipsychotics; Phenothiazines; Dopamine Antagonists
Drug Type: Small Molecule; Approved
Absorption: Absolute bioavailability is 40% following oral administration.
Toxicity (Overdose): Symptoms of overdose include stupor or coma, and children may have convulsive seizures. Signs of arousal may not occur for 48 hours. Oral LD50=318 mg/kg (rat); IPR LD50=64 mg/kg (mouse)
Protein Binding: Not Available
Half Life: 8-12 hours, but ranges up to 20 hours.
Dosage Forms of Etrafon-A: Liquid Oral
Chemical IUPAC Name: 2-[4-[3-(2-chlorophenothiazin-10-yl)propyl]piperazin-1-yl]ethanol
Chemical Formula: C21H26ClN3OS
Perphenazine on Wikipedia: https://en.wikipedia.org/wiki/Perphenazine
Organisms Affected: Humans and other mammals