12.5mg/ml (1ml amp)
Each ml contains Prochlorperazine
Colourless or almost colourless
ACTIONS & MODE OR MECHANISMS OF ACTIONS:
Prochloperazine is a phenothiazine with a piperazine moiety in the side
chain. It processes strong antiemetic and antipsychotic activity with less
sedative action than chlorpromazine. As with other phenothiazines,
prochloperazine has actions on several neurotransmitter systems:
1. Antidopamine action, which probably contributes to both the therapeutic
effect and unwanted effects including extrapyramidal disorders and endocrine
2. Alpha-adrenoceptors antagonism, which contributes to cardiovascular side
effects such as orthostatic hypotension and reflex tachycardia.
3. Potentiation of noradrenaline by blocking its reuptake into nerve terminals.
4. Weak antiacetylcholinre action.
5. Weak antihistanminic action.
6. Weak serotonin antagonism.
Prochlorperazine also has an effect on temperature control and blocks
conditioned avoidance responses.
There are few published data on prochlorperazine pharmacokinetics in humans.
Most studies have been done in rats and dose levels do not correspond to
those used clinically and metabolic pathway may differ. Similar overall
pharmacokinetic patterns however would occur in humans. Prochlorperazine is
well absorbed from the gastrointestinal tract in rats but absorption is
slowed in repeatedly treated animal. The drug is widely distributed to
tissues including the brain, fat, kidney, heart and skin and is stored in
reticuloendothelial tissues. Phenothiazines are metabolized primarily in the
liver and are subject to enterohepatic circulation. Excretion is mainly in
the faeces. Only a very small amount (approx. 0.1%) of prochlorperazine and
its metabolites are excreted in the first 24 hours in the urine and the drug
may continue to be excreted in the urine for up to 3 weeks after cessation
of long term therapy. The elimination half-life is approximately 24 hours,
presumably due to its enterohepatic circulation.
Nausea and vomiting due to various causes including migraine; vertigo due to
Meniere's syndrome, labyrinthitis and other causes; minor mental and
Circulatory collapse, central nervous system depression (coma or drug
intoxication), previous history of a hypersensitivity reaction (eg. jaundice
or blood dyscrasia) to phenothiazines especially to prochlorperazine, bone
SIDE EFFECTS/ADVERSE REACTIONS
The following reactions have been reported for prochloperazine or
phenothiazines in general.
More common reactions
Gastrointestinal: constipation, dry mouth.
Nervous System: Drowsiness, akathisia, parkinsonism (with
dyskinesia, tremor and rigidity).
Ocular: Blurred vision.
Less common reaction
Biochemical abnormalities: elevated serum level of bilirubin
and hepatic enzymes may occur if the patient develops cholestatic jaundice.
Cardiovascular: hypotension, propheral oedema, cardiac
arrhytmias, ECG changes.
Dermatological: dermatitis, maculopopular eruption, erythema,
multiform, urticaria, photosensitivity, abnormal pigmentation.
Gastrointestinal: paralytic ileus.
Genito-urinary: urinary retention, inhibition of ejaculation.
Haematological: agranulocytosis, atypical lymphocytes,
thrombocytopenia, leucopenia, aplastic anaemia.
Hepatic: cholestatic jaundice, liver damage.
Nervous System: acute dystonic reactions, seizures, EEG
changes, headache, insomnia, catatonia.
Psychiatric: Activation of psychotic symptoms.
Serious or life threatening reactions:
Prochloperazine can cause very serious acute dystonic reactions in children
leading cyanosis from laryngospasm, apnoea requiring artificial ventilation,
life threatening tetanus like syndromes, coma and even death. These reaction
can occur with a single therapeutic dose. For treatment, see Overdosage.
Also, long term phenothiazine therapy has been associated with ECG changes
and life threatening cardiac arrhythmias.
This preparation contains sulphite that may cause allergic type
reactions including anaphylactic symptoms and life threatening or less
severe asthmatic episodes in certain susceptible individuals. Sulphite
sensitivity is seen more frequently in asthmatic patients.
Prochlorperazine should be
avoided in patients with renal dysfunction, Parkinson's disease,
hypothyroidism, phaeochromocytoma, myasthenia gravis, prostate hypertrophy
The autonomic side effects of the piperazine derivatives are less
troublesome than those of other phenothiazines, however care should be taken
if prochloperazine injection is used in the elderly or in patients
undergoing surgery with spinal anaesthesia.
Piperazine derivatives are also less epileptogenic than other phenothiazines,
but care should still be exercised in epileptic patients.
Prochlorperazine can cause problems due to anticholinergic effects,
especially in the elderly (urinary difficulties, constipation and
precipitation of acute narrow angle glaucoma), but to a lesser extent than
with other phenothiazines.
It appears from a study of 5 hypocalcaemic patients with hypoparathyroidism
that such patients are particularly prone to acute severe dystonic reactions
Prochlorperazine may impair
mental and physical activity especially during the first few days of
therapy. Patients should be warned about activities requiring alertness.
The antiemetic effects of
prochloperazine may mask signs of overdosage of toxic drugs or obscure the
diagnosis of conditions such as intestinal obstruction and brain tumour.
Severe hypothermia may occur
during swimming in cold water or in patients receiving antipyretic therapy.
Caution should be used in
patients with existing liver disease due to the extensive hepatic metabolism
of prochlorperazine. A past history of jaundice resulting from phenothiazine
therapy indicates a hypersensitivity reaction and there is a likelihood of
cross sensitivity to other phenothiazines.
Tardive dyskinesia may develop in
patients on antipsychotic drugs. The disorder consist repetitive involuntary
movements of the tongue, face, mouth or jaw (eg. protrusion of tongue,
puffing of cheeks, puckering of mouth, chewing movements). The trunk and
limbs are less frequently involved. It has been reported that form
vermicular movement of the tongue may be an early sign of the syndrome. Both
the risk of developing the syndrome and the likelihood that it will become
irreversible are believed to increase as the duration of treatment and the
total cumulative dose of the drug increases. Less commonly, the syndrome can
develop after relatively brief treatment periods at low doses. The risk
seems to greater in elderly patients, especially females. The syndrome may
become clinically recognizable either drug treatment, or upon dosage
reduction, or upon withdrawal of treatment. The dosage of antipsychotic drug
should be reduced periodically (if clinically possible) and the patient
observed for the sign of the disorder, since the syndrome may be masked by a
In patients requiring long-term treatment, the smallest dose and the
shortest duration of treatment producing a satisfactory clinical response
should be sought. There is no known effective treatment for tardive
dyskinesia. Antiparkinson agents usually do not alleviate the symptoms of
this syndrome, if theses symptoms appear, it is suggested that the
antipsychotic be discontinued if symptoms of tardive dyskinesia appear.