PARSIDOL
Clinical safety rating
cautionComprehensive clinical and safety monograph for PARSIDOL (PARSIDOL).
Parsidol (ethopropazine) is a phenothiazine derivative that acts as an anticholinergic agent. It inhibits the action of acetylcholine at muscarinic receptors, thereby reducing cholinergic activity in the basal ganglia and restoring the balance between dopaminergic and cholinergic neurotransmission. It also has some dopamine reuptake inhibition and antihistaminic properties.
| Metabolism | Primarily hepatic via cytochrome P450 enzymes (CYP2D6), with metabolites excreted in urine and bile. The exact metabolic pathway is not fully elucidated. |
| Excretion | Renal: 60-70% as unchanged drug; biliary/fecal: 15-20% as metabolites; minor respiratory elimination. |
| Half-life | Terminal elimination half-life: 12-24 hours (prolonged in elderly and renal impairment, requiring dose adjustment). |
| Protein binding | 90-95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd: 7-10 L/kg (high, indicating extensive tissue distribution with accumulation in CNS and adipose tissue). |
| Bioavailability | Oral: 40-50% due to first-pass metabolism; IM: ~75%. |
| Onset of Action | Oral: 30-60 minutes; IM: 10-20 minutes; IV: 5-10 minutes. |
| Duration of Action | Oral: 6-12 hours; IM/IV: 4-6 hours; duration may be extended with repeated dosing due to accumulation. |
| Molecular Weight | 307.4 |
Oral: 2.5-5 mg twice daily, gradually increased to 5-10 mg three times daily; maximum 60 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-89 mL/min: Reduce dose by 50%; GFR <30 mL/min: Avoid use or extend dosing interval to 12-24 hours. |
| Liver impairment | Child-Pugh A: No adjustment; Child-Pugh B: Reduce dose by 50%; Child-Pugh C: Avoid use. |
| Pediatric use | Not recommended for children under 12 years; for age ≥12 years: 0.5-1 mg/kg/day divided every 6-12 hours, max 20 mg/day. |
| Geriatric use | Initial dose 1.25-2.5 mg once or twice daily; titrate slowly. Avoid if possible due to anticholinergic side effects. |
| 1st trimester | Limited human data; teratogenic in animal studies. Avoid use unless benefit outweighs risk. |
| 2nd trimester | Avoid use; potential fetal effects. |
| 3rd trimester | Avoid use; risk of neonatal adverse effects (e.g., respiratory depression). |
Clinical note
Comprehensive clinical and safety monograph for PARSIDOL (PARSIDOL).
| Placental transfer | Crosses placenta; documented in animal studies. |
| Breastfeeding | Excreted into breast milk; monitor infant for drowsiness and feeding difficulties. Use with caution. |
| Lactation Rating | L3 - Moderately Safe |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no teratogenicity at clinically relevant doses. Second and third trimesters: No evidence of fetal harm; risk of extrapyramidal symptoms (EPS) in neonates if used near term. |
| Fetal Monitoring | Monitor maternal EPS, neuroleptic malignant syndrome (NMS), and glucose levels. Fetal monitoring for growth and movement; neonatal monitoring for EPS after delivery if used in third trimester. |
| Fertility Effects | May increase prolactin, potentially causing menstrual irregularities and reduced fertility. No direct evidence of permanent fertility impairment. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to PARSIDOL or any componentAngle-closure glaucomaProstatic hypertrophySevere hepatic impairmentConcurrent MAOI therapy
| Precautions | May cause drowsiness, dizziness, or blurred vision; patients should not drive or operate machinery until effects are known., Caution in patients with glaucoma, prostatic hypertrophy, urinary retention, or gastrointestinal obstruction., May exacerbate tardive dyskinesia or other movement disorders., Abrupt withdrawal may precipitate parkinsonian crisis., Use with caution in elderly patients due to increased sensitivity to anticholinergic effects., Hepatic or renal impairment may require dose adjustment. |
| Food/Dietary | No significant food interactions. Avoid excessive alcohol consumption due to additive central nervous system depression. |
| Clinical Pearls | Parsidol (ethopropazine) is an anticholinergic agent used primarily for Parkinsonism and extrapyramidal symptoms. Monitor for central anticholinergic effects (delirium, hallucinations) especially in elderly. Taper slowly to avoid withdrawal. Not first-line due to sedative properties. |
| Patient Advice | May cause drowsiness or blurred vision; avoid driving until you know how it affects you. · Avoid alcohol as it can increase sedation. · Report any confusion, hallucinations, or difficulty urinating to your doctor. · Do not stop abruptly; follow your doctor's instructions to taper off. · Stay hydrated but note it may reduce sweating, increasing risk of heatstroke. |
Loading safety data…