Perphenazine (12 brand names, 5 dosage forms, 2 routes)
Available dosage forms: TABLET, CONCENTRATE, INJECTABLE, TABLET, EXTENDED RELEASE, SYRUP.
Routes of administration: ORAL, INJECTION.
Brand Names
- ETRAFON 2-10
- ETRAFON 2-25
- ETRAFON-A
- ETRAFON-FORTE
- PERPHENAZINE
- PERPHENAZINE AND AMITRIPTYLINE HYDROCHLORIDE
- TRIAVIL 2-10
- TRIAVIL 2-25
- TRIAVIL 4-10
- TRIAVIL 4-25
- TRIAVIL 4-50
- TRILAFON
Indications and Usage
Perphenazine is indicated for use in the treatment of schizophrenia and for the control of severe nausea and vomiting in adults. Perphenazine has not been shown effective for the management of behavioral complications in patients with mental retardation.
Dosage and Administration
Dosage must be individualized and adjusted according to the severity of the condition and the response obtained. As with all potent drugs, the best dose is the lowest dose that will produce the desired clinical effect. Since extrapyramidal symptoms increase in frequency and severity with increased dosage, it is important to employ the lowest effective dose. These symptoms have disappeared upon reduction of dosage, withdrawal of the drug, or administration of an antiparkinsonian agent. Prolonged administration of doses exceeding 24 mg daily should be reserved for hospitalized patients or patients under continued observation for early detection and management of adverse reactions. An antiparkinsonian agent, such as trihexyphenidyl hydrochloride or benztropine mesylate, is valuable in controlling drug-induced extrapyramidal symptoms. Suggested dosages for various conditions follow:
Contraindications
Perphenazine products are contraindicated in comatose or greatly obtunded patients and in patients receiving large doses of central nervous system depressants (barbiturates, alcohol, narcotics, analgesics, or antihistamines); in the presence of existing blood dyscrasias, bone marrow depression, or liver damage; and in patients who have shown hypersensitivity to perphenazine products, their components, or related compounds. Perphenazine products are also contraindicated in patients with suspected or established subcortical brain damage, with or without hypothalamic damage, since a hyperthermic reaction with temperatures in excess of 104°F may occur in such patients, sometimes not until 14 to 16 hours after drug administration. Total body ice-packing is recommended for such a reaction; antipyretics may also be useful.
Adverse Reactions
Not all of the following adverse reactions have been reported with this specific drug; however, pharmacological similarities among various phenothiazine derivatives require that each be considered. With the piperazine group (of which perphenazine is an example), the extrapyramidal symptoms are more common, and others (e.g., sedative effects, jaundice, and blood dyscrasias) are less frequently seen.
Drug Interactions
Metabolism of a number of medications, including antipsychotics, antidepressants, ß-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 “poor” 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.
Overdosage
In the event of overdosage, emergency treatment should be started immediately. Consultation with a poison center should be considered. All patients suspected of having taken an overdose should be hospitalized as soon as possible.