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Drug
information
Pharmacokinetics
| Indication
& Dosage | Interactions
Adverse
Effects & Precautions |
Brands available in Market
Pharmacokinetics
The
pharmacokinetics of thioridazine appear to be generally similar to those
of chlorpromazine The principal active metabolite of thioridazine
is mesoridazine the metabolite, sulforidazine, also has some
activity. Thioridazine and its active metabolites are reported to be
highly bound to plasma proteins. The plasma half-life of thioridazine
has been estimated to range from about 6 to over 40 hours.
Anxiety, mixed anxiety dpression, tension & agitation, psychosomatic disorders, emotional distrubances. Geriatric senile agitation & confusional states. Paediatrics: Additionally difficulty of concentration, behavioural disorders, hyperactivity, aggressiveness
Dosage: Adult: Schizophrenia & Other psychoses: 150-600mg (initially in divided doses): max. 800mg daily for upto 4 weeks. Severe anxiety and agitation: 30-100mg daily.
Children: 1-5 year: 1mg/kg daily, 5-12 years: 75-150mg daily (upto 300mg in severe cases).
Interactions
The most common
interactions encountered with phenothiazines are adverse effects
resulting from concomitant administration of drugs with similar
pharmacological actions. When given with other drugs that produce
orthostatic hypotension dosage adjustments may be necessary.
However, it should be noted that phenothiazines have been reported
to reduce the antihypertensive action of guanethidine and other
adrenergic neurone blockers. As many phenothiazines possess
antimuscarinic actions they may potentiate the adverse effects of
other drugs with antimuscarinic actions, including tricyclic
antidepressants and the antimuscarinic antiparkinsonian drugs that
may be given to treat phenothiazine-induced extrapyramidal
effects. In theory, antipsychotics with dopamine-blocking activity
and dopaminergic drugs such as those used to treat parkinsonism
may be mutually antagonistic. Concomitant administration of
metoclopramide may increase the risk of antipsychotic-induced
extrapyramidal effects.
There is an increased risk of arrhythmias when antipsychotics are used with drugs which prolong the QT interval including certain antiarrhythmics, antihistamines, antimalarials, and cisapride. There is also an increased risk of arrhythmia when tricyclic antidepressants are used with antipsychotics which prolong the QT interval. Because of an increased risk of seizures the US manufacturers recommend discontinuation of chlorpromazine before the use of metrizamide for radiographic procedures. Symptoms of CNS depression may be enhanced by other drugs with CNS-depressant properties including alcohol, general anaesthetics, hypnotics, anxiolytics, and opioids.
Adverse
Effect &Precautions
Sedation,
drowsiness, interference with male sexual function, dry mouth,
blood dyscrasias, eye damage and hypersensitivity.
Precaution: Liver damage. Cardiovascular disease.
Pregnancy: Use with caution.
Breast Feeding: Use with caution.
Man: May be given in reduced dose.
