Stemetil (prochlorperazine) is a "high-risk" antipsychotic-antiemetic drug to be used with caution, according to manufacturer's directives. Indications of prochlorperazine are primarily in the management of "psychotic disorders".

Stemetil enters the enterohepatic circulation and is excreted chiefly in the feces. The drug undergoes metabolism in the gastric mucosa and on first pass through the liver. Anti-emetic effect of prochlorperazine is diminished by its low bioavailability owing to a significant gastric and hepatic first pass effect.

 Further, "unexplained, sudden deaths" have occurred in hospitalized patients treated with this type of drug. The adverse effects of phenothiazines can affect all organ systems and may be attributed either to the drug's effects on the central and autonomic nervous system, or to hypersensitivity reactions to the drug-reaction.

Symptoms of overdosage include CNS depression which may vary from simple lethargy to coma. Other possible manifestations include convulsions, autonomic reactions such as hypotension, and ileus.

Stemetil is contraindicated in the presence of circulatory collapse, altered states of consciousness or comatose states, particularly when these are due to intoxication with central depressant drugs. It is contraindicated in severely depressed patients, in the presence of blood dyscrasias, liver disease, renal insufficiency, pheochromocytoma, or in patients with severe cardiovascular disorders or a history of hypersensitivity to phenothiazine derivatives. Blood DYSCRASIA = any abnormal condition of the blood .

Stemetil must not be given to anyone who is unconscious or in a coma. Compare;  Anticholinergic Syndrome - in which the clinical diagnosis is based on the appearance of the anticholinergic toxidrome, ie. altered mental status, disorientation, incoherent speech, somnolence, coma, central respiratory failure, and, rarely, seizures.

The use of Stemetil is CONTRAINDICATED to emesis in coma, trauma, toxic syndromes, and in anyone with impaired airway or laryngeal cough reflexes and can result in POISONING. The possible roles of airway compromise during and prior to intubation and or aspiration of vomitus are difficult to assess.

Loss of airway is the most lethal toxicological complication.

Prochlorperazine is widely distributed into body tissues and fluids (in this case tissues and fluids containing a resistant bacteria - disseminated bacteria can cross blood/brain barrier) and crosses the blood-brain barrier (BBB) due to increased penetration of the blood-brain barrier. Infection is rapid once organism crosses the BBB. Further, findings suggest that from the lungs, S. pneumoniae often invades the blood, crosses the blood-brain barrier, and enters the meninges.

Stemetil is a phenothiazine piperazine derivative in addition to being an antipsychotic with a piperazine side chain, similar to trifluoperazine and fluphenazine. Because of the similarity in antiemetic action of the trifluoperazine component, Stemetil should NOT be used where nausea and vomiting are believed to be evidence of intestinal obstruction or brain tumor, for the same reasons as Stelabid, for example.

Symptoms of central nervous system depression to the point of somnolence or coma are usually associated with overdosage, and multiple drug-therapy associated with toxic and metabolic causes is common in overdosage situations.

Symptoms of phenothiazine overdosage include drowsiness or loss of consciousness, hypotension, tachycardia, ECG changes, ventricular arrhythmias and hypothermia. Cardiac arrhythmias explained. 

The antiemetic action of prochlorperazine may mask the signs and symptoms of overdosage of other and may obscure the diagnosis and treatment of other conditions such as intestinal obstruction. Deep sleep, from which patients can be aroused, and coma have been reported, usually with overdosage.

The drug is also contraindicated in the presence of liver disease, renal insufficiency, or in patients with cardiovascular disorders.