Introduction to Stemetil: A Closer Look at an Older Drug
Stemetil, the brand name for the drug prochlorperazine, is a medication in the phenothiazine class used to treat severe nausea, vomiting, dizziness (vertigo), and migraines. It works by blocking dopamine receptors in the brain, which affects the parts of the brain that control nausea and vomiting. While it is highly effective, its mechanism of action, characteristic of older, or first-generation, antipsychotics, is the root cause of its most significant drawbacks. The potential problems with Stemetil are numerous and can be severe, warranting careful consideration before use, especially for long-term treatment.
Serious Neurological Problems
As a dopamine antagonist, Stemetil poses a risk of serious, and in some cases, irreversible neurological disorders. Patients and healthcare providers must be vigilant for these symptoms.
Extrapyramidal Symptoms (EPS)
Extrapyramidal symptoms are movement-related side effects that can appear shortly after starting the medication. The risk is higher with higher doses or in vulnerable populations like children and the elderly.
- Dystonia: This involves involuntary, sustained muscle contractions that can lead to twisting and repetitive movements or abnormal postures. These can affect the neck, tongue, jaw, or eyes, and can sometimes be severe enough to cause difficulty swallowing or breathing.
- Akathisia: Characterized by a feeling of inner restlessness that can lead to the inability to sit or stand still. Patients may fidget, pace, or constantly shift their weight.
- Pseudoparkinsonism: This resembles the symptoms of Parkinson's disease, including tremors, a mask-like facial expression, a shuffling gait, and muscle rigidity.
Tardive Dyskinesia (TD)
One of the most serious and feared problems with Stemetil is the risk of tardive dyskinesia, a potentially irreversible neurological disorder. The risk increases with the duration of treatment and the cumulative dose.
- Involuntary Movements: TD is characterized by involuntary, rhythmic movements, most commonly affecting the face, lips, tongue, and jaw (e.g., smacking, puckering, grimacing, tongue protrusion).
- Masking of Symptoms: The medication itself can suppress the signs of TD, potentially masking the underlying neurological damage.
- High-Risk Groups: Elderly patients, especially women, have a higher prevalence of developing TD.
Neuroleptic Malignant Syndrome (NMS)
Though rare, NMS is a life-threatening reaction to antipsychotic drugs, including Stemetil. It is a medical emergency that requires immediate discontinuation of the drug and intensive medical care.
- Symptoms: Key symptoms include hyperpyrexia (high fever), severe muscle rigidity, altered mental status, and autonomic instability (irregular pulse or blood pressure).
Significant Drug Interactions and Contraindications
Stemetil has numerous significant drug interactions and should be used with caution, if at all, in patients with certain conditions.
- CNS Depressants: The combination of Stemetil with other CNS depressants, such as alcohol, opioids, or sleeping pills, can increase sedation and cause dangerous side effects.
- Dementia-Related Psychosis: The FDA has issued a boxed warning indicating an increased risk of death when older patients with dementia-related psychosis are treated with antipsychotic drugs, including prochlorperazine.
- Contraindicated Conditions: Patients with severe CNS depression, known hypersensitivity to phenothiazines, severe cardiac issues, narrow-angle glaucoma, or a history of tardive dyskinesia should not take Stemetil.
- Interference with Other Drugs: Stemetil can interfere with the effects of oral anticoagulants and can have a large number of other drug interactions.
Risk of Withdrawal Symptoms
Abrupt discontinuation of Stemetil, especially after prolonged use, can lead to withdrawal symptoms. It is crucial to gradually taper the dose under a doctor's supervision.
- Symptoms of Withdrawal: These can include nausea, vomiting, diarrhea, dizziness, tremors, and a return of or worsening of pre-existing anxiety.
Comparison: Stemetil vs. Newer Antiemetics
To put the problems with Stemetil into perspective, comparing it to a newer antiemetic like ondansetron is helpful.
| Feature | Stemetil (Prochlorperazine) | Ondansetron (e.g., Zofran) |
|---|---|---|
| Drug Class | First-generation antipsychotic, phenothiazine | Serotonin (5-HT3) receptor antagonist |
| Mechanism | Blocks dopamine (D2) receptors, among others | Blocks serotonin receptors |
| Serious Neurological Risk | High risk for EPS, TD, and NMS | Very low risk for EPS, TD, and NMS |
| Cardiovascular Risk | Can cause low blood pressure and is cautioned in heart disease; Boxed Warning for elderly dementia patients | May cause QT prolongation, but generally safer in this regard |
| Common Side Effects | Drowsiness, dry mouth, blurred vision, dizziness | Headache, constipation, malaise |
| Pregnancy/Pediatric Use | Generally not recommended for pregnancy; pediatric use requires caution due to higher risk of side effects | Safer profile, sometimes used off-label for pediatric nausea |
Other Notable Problems
In addition to the serious risks, Stemetil can cause several other bothersome or significant side effects that impact a patient's quality of life.
- Sedation and Dizziness: This can severely impair the ability to drive or operate machinery, especially when treatment begins.
- Low Blood Pressure: Particularly when standing up quickly (orthostatic hypotension), leading to falls.
- Temperature Regulation Issues: Stemetil can impair the body's ability to regulate temperature, making patients more susceptible to both heat and cold.
- Hormonal Changes: Can cause elevated prolactin levels, leading to breast enlargement, milk production, and menstrual cycle irregularities.
- Anticholinergic Effects: Including dry mouth, constipation, and blurred vision.
- Changes in Blood Cell Counts: Rarely, Stemetil can lower white blood cell counts, increasing the risk of infection.
Conclusion
What is the problem with Stemetil is multifaceted, stemming from its classification as a first-generation antipsychotic. While effective for its indicated uses, its potential for serious and sometimes irreversible side effects, such as tardive dyskinesia and neuroleptic malignant syndrome, must be carefully weighed against the benefits. The existence of newer, safer alternatives for many of its uses, particularly for nausea and vomiting, means Stemetil is often not the first choice of treatment. For patients and healthcare providers, a full understanding of these risks, contraindications, and drug interactions is essential for safe prescribing and patient management. Informed discussions are crucial, especially for long-term therapy or for patients in high-risk groups, to determine if the potential benefits outweigh the significant hazards. For more detailed medical information, see the MedlinePlus drug information on prochlorperazine.
