PHARMACOLOGY

Pharmacotherapeutic Group: Antiemetic and antipsychotics

Pharmacodynamic properties: 

Prochlorperazine blocks both postsynaptic dopamine receptors as well as the medullary chemoreceptor trigger zone. It depresses hypothalamic and hypophyseal hormone release and posssesses α-adrenergic and anticholinergic inhibitory activity.

Pharmacokinetic properties:

Absorption: Well absorbed from the GI tract but is subject to considerable first pass metabolism from the gut wall. Bioavailability: 12.5%, onset: 30-40 min

Distribution: Extensively bound to plasma proteins, widely distributed in the body (it crosses the blood brain barrier) and its metabolites cross the placental barrier and are excreted in milk.

Metabolism: Extensively metabolised in the liver and forms N-desmethylprochlorperazine (active), excreted in the urine and bile.

Excretion: Plasma half-life is reported to be only a few hours but elimination of the metabolites may be very prolonged.

 INDICATIONS

Nausea and vomiting associated with radiotherapy and chemotherapy, pre and post operation, vertigo, schizophrenia, mania 

DOSE

Adult: 5-10 mg twice or three times a day.

Pediatric:

Less than 2 years old: not recommended

Greater than 2 years old: 2.5-5 mg every 8-12 hr

CONTRAINDICATIONS

Children less than 2 years, lactation, hypersensitivity to phenothiazines, coma, severe CNS depression

SPECIAL PRECAUTIONS

Extrapyramidal syndrome, hypotension, epilepsy, impaired hepatic, renal, cardiovascular, cerebrovascular or respiratory function, glaucoma. May impair ability to drive or perform tasks requiring mental alertness or physical coordination. History of jaundice, parkinsonism, diabetes mellitus, hypothyroidism, myasthenia gravis, paralytic ileus, prostatic hyperplasia or urinary retention. Regular eye examinations are recommended in patients on long-term treatment

 ADVERSE DRUG REACTIONS

Severe AEs: Bone-marrow suppression, cardiac arrhythmias or aspiration.

Common AEs: Jaundice, cardiac arrhythmias, orthostatic hypotension, leucopenia, thrombocytopenia, dry mouth, blurring of vision, glaucoma, urinary retention, constipation, galactorrhoea, gynaecomastia, amenorrhoea

 DRUG INTERACTIONS

Potentiation of other CNS depressants including alcohol, sedatives, hypnotics, barbiturates, opioids, antihistamines and general anaesthetics.

PRESENTATION

Each box is supplied with 20 strips of 10 tabs packed in blisters