DISIPAL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DISIPAL (DISIPAL).
Disipal (orphenadrine) is a centrally acting anticholinergic agent that blocks muscarinic acetylcholine receptors in the central nervous system, reducing cholinergic overactivity. It also exhibits local anesthetic and antihistaminic properties.
| Metabolism | Hepatic metabolism via N-demethylation and N-oxide formation, primarily by CYP450 enzymes (CYP3A4, CYP2D6). |
| Excretion | Primarily renal (approximately 70-80% as unchanged drug and metabolites), with the remainder via biliary/fecal elimination. |
| Half-life | Terminal elimination half-life: 12-15 hours; steady-state achieved after 3-5 days. |
| Protein binding | Approximately 90-95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd: 5-10 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability: 70-80% (first-pass metabolism limited); IM: 90-95%; IV: 100%. |
| Onset of Action | Oral: within 30-60 minutes; intramuscular: 10-15 minutes; intravenous: 2-5 minutes. |
| Duration of Action | 6-12 hours for motor symptoms; shorter for mental effects (2-4 hours). Clinical note: Dosing frequency may need adjustment based on response. |
5 mg oral twice daily, titrated to a maximum of 15 mg/day in divided doses.
| Dosage form | TABLET |
| Renal impairment | GFR <30 mL/min: reduce dose by 50% or increase dosing interval to 12-24 hours. |
| Liver impairment | Child-Pugh class B: reduce dose by 50%; class C: avoid use. |
| Pediatric use | 0.02-0.05 mg/kg/dose twice daily, max 5 mg/day. |
| Geriatric use | Initiate at 2.5 mg daily, titrate slowly; monitor for anticholinergic effects and falls. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DISIPAL (DISIPAL).
| Breastfeeding | Excretion into breast milk unknown; M/P ratio not available. Infants are highly sensitive to anticholinergic effects; avoid use unless benefit clearly outweighs risk. |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no consistent teratogenicity. Second and third trimesters: Risk of neonatal anticholinergic effects (e.g., decreased GI motility, urinary retention). No known major malformation risk. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to orphenadrine or any component","Narrow-angle glaucoma","Myasthenia gravis","Obstructive uropathy (e.g., prostatic hypertrophy)","Severe hepatic or renal impairment","Concurrent use with other anticholinergic agents"]
| Precautions | ["Anticholinergic effects: confusion, hallucinations, urinary retention, constipation, blurred vision","May exacerbate glaucoma, myasthenia gravis, prostatic hypertrophy, or gastrointestinal obstruction","Central nervous system effects: drowsiness, dizziness (avoid driving or operating heavy machinery)","Risk of toxicity in elderly patients or those with hepatic/renal impairment","Potential for abuse and dependence"] |
Loading safety data…
| Monitor maternal heart rate, blood pressure, gastrointestinal motility, and urinary output. Assess neonatal heart rate, feeding behavior, and bowel function postnatally. |
| Fertility Effects | Anticholinergic properties may reduce fertility in females via cervical mucus thickening; no known effect on male fertility. |