What are the side effects of Stemetil (prochlorperazine)?

Side Effects of Stemetil (Prochlorperazine)

Prochlorperazine (Stemetil) can cause significant side effects including CNS depression, extrapyramidal symptoms, anticholinergic effects, and rarely serious complications like neuroleptic malignant syndrome and tardive dyskinesia. 1, 2

Common Side Effects

• Central Nervous System Effects:

  • Sedation and drowsiness 1
  • Dizziness 1, 2
  • Cognitive impairment 1

• Extrapyramidal Symptoms (occur in up to 16% of patients):

  • Akathisia (restlessness, inability to remain still) - most common, occurring in 14-16% of patients 3, 4
  • Dystonia (abnormal muscle contractions) - occurs in approximately 4% of patients 3
  • Pseudoparkinsonism 1
  • Tardive dyskinesia with long-term use 5

• Anticholinergic Effects:

  • Dry mouth (xerostomia) 1
  • Constipation 1
  • Urinary retention 1
  • Blurred vision 1

• Cardiovascular Effects:

  • Hypotension 1
  • Tachycardia 1
  • Arrhythmias 1

Serious Side Effects

• Neuroleptic Malignant Syndrome (NMS): A rare but potentially fatal complication characterized by:

  • Hyperpyrexia (high fever)
  • Muscle rigidity
  • Altered mental status
  • Autonomic instability (irregular pulse/blood pressure, tachycardia, diaphoresis) 2

• Blood Disorders:

  • Drug-induced leukopenia or neutropenia 1

• Hepatotoxicity: Liver function abnormalities 2

• Fall Risk: Causes somnolence, postural hypotension, and motor/sensory instability that may lead to falls and injuries 2

Special Population Considerations

• Pregnancy: Not recommended during pregnancy except in cases of severe, intractable nausea and vomiting where potential benefits outweigh risks 2

• Nursing Mothers: Phenothiazines are excreted in breast milk; caution advised 2

• Children: Side effects in children are predominantly neurological and include:

  • Impaired consciousness
  • Dyskinesia (most frequent)
  • Pyramidal signs
  • Hypertonus 6

• Elderly: Higher risk of sedation, falls, and extrapyramidal symptoms 1

Timing of Side Effects

• Akathisia typically occurs within a week of starting treatment 4
• Extrapyramidal symptoms may appear during the first few days of therapy 2
• Tardive dyskinesia is associated with long-term use 5

Risk Factors for Side Effects

• History of bone marrow depression 2
• Previous hypersensitivity reaction to phenothiazines 2
• Concomitant use of other CNS depressants (alcohol, anesthetics, narcotics) 2
• Hepatic or renal impairment 1
• Advanced age 1

Management of Side Effects

• For extrapyramidal symptoms: Orphenadrine (Disipal) can provide immediate relief 6
• For NMS: Immediate discontinuation of the drug, intensive symptomatic treatment, and medical monitoring 2
• Consider alternative antiemetics that don't pose risk of movement disorders (e.g., ondansetron, granisetron) 5

Monitoring Recommendations

• Monitor for early signs of neurologic toxicity, especially if combined with other medications 2
• Complete fall risk assessments when initiating treatment and periodically for long-term therapy 2
• Monitor liver function, especially in patients with underlying hepatic disease 2

Remember that prochlorperazine should be used with caution, particularly in elderly patients and those with a history of extrapyramidal reactions or other risk factors for side effects 1, 2.