Stemetil (Prochlorperazine) Effects on Prolactin Levels
Yes, Stemetil (prochlorperazine) significantly increases prolactin levels due to its dopamine receptor antagonism properties. Prochlorperazine belongs to the phenothiazine class of antipsychotics, which are known to cause hyperprolactinemia through their blockade of D2 receptors in the pituitary gland.
Mechanism of Action
- Antipsychotic medications like prochlorperazine block dopamine D2 receptors in the tuberoinfundibular pathway, reducing the inhibitory effect of dopamine on prolactin secretion 1, 2
- Dopamine normally maintains a tonic inhibition of prolactin secretion from anterior pituitary lactotrophs; when this inhibition is blocked, prolactin levels rise 2
- The effect is dose-dependent, with higher doses causing greater increases in prolactin levels 3
Evidence for Phenothiazine Effects on Prolactin
- Studies with perphenazine (another phenothiazine antipsychotic similar to prochlorperazine) demonstrate significant dose-dependent increases in plasma prolactin levels in both men and women 3
- Typical antipsychotics like prochlorperazine have high affinity for D2 receptors and slow dissociation rates, leading to sustained hyperprolactinemia 2
- The Endocrine Society recognizes antipsychotic medications as one of the most common causes of medication-induced hyperprolactinemia 1
Clinical Implications of Elevated Prolactin
- Hyperprolactinemia can cause:
- Prolonged hyperprolactinemia may contribute to decreased bone mineral density due to hypogonadism 5
Monitoring and Management
For patients on prochlorperazine who develop symptoms of hyperprolactinemia, consider:
- Measuring serum prolactin levels (a single measurement at any time of day is usually sufficient) 4
- Excluding other causes of hyperprolactinemia such as hypothyroidism, renal or hepatic impairment 4, 1
- If prolactin levels are only modestly elevated, repeat measurements to rule out stress-induced elevations 4
Management options for symptomatic hyperprolactinemia include:
- Switching to an antipsychotic with lower propensity to elevate prolactin (if clinically appropriate) 5
- Hormone replacement therapy for symptomatic hypogonadism 5
- In some cases, cautious addition of a dopamine agonist may be considered, though this may interfere with the therapeutic effect of the antipsychotic 5
Important Distinctions
- Unlike newer atypical antipsychotics (such as cariprazine) which have minimal effects on prolactin 6, phenothiazines like prochlorperazine consistently cause significant prolactin elevation
- The degree of prolactin elevation with prochlorperazine is typically proportional to the dose and duration of treatment 3
Recognizing this side effect is important for proper monitoring and management of patients on Stemetil (prochlorperazine), especially for long-term use.