DONEPEZIL HYDROCHLORIDE
Clinical safety rating: caution
Animal studies have proved adverse effects but may be safe for humans
Reversible inhibitor of acetylcholinesterase, increasing acetylcholine concentration in the synaptic cleft of the central nervous system.
| Metabolism | Extensively metabolized by CYP2D6 and CYP3A4; undergoes glucuronidation and N-oxidation. |
| Excretion | Renal (26% unchanged), fecal (57%, primarily as metabolites via biliary excretion) |
| Half-life | Terminal elimination half-life approximately 70 hours (range 50-100 hours), allowing once-daily dosing; steady-state reached in 14-21 days |
| Protein binding | 96% bound primarily to albumin (approx. 75%) and alpha1-acid glycoprotein |
| Volume of Distribution | 11-12 L/kg, indicating extensive extravascular distribution, including CNS penetration |
| Bioavailability | 100% oral bioavailability (no significant first-pass metabolism) |
| Onset of Action | Oral: 2-4 weeks for clinical improvement in cognitive function; peak plasma levels at 3-4 hours but no immediate clinical effect |
| Duration of Action | 24 hours due to long half-life; clinical effects persist for weeks after discontinuation due to sustained acetylcholinesterase inhibition |
Alzheimer's disease: Initial 5 mg orally once daily at bedtime for 4-6 weeks, increase to 10 mg once daily. Maximum dose 10 mg/day.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (CrCl < 10 mL/min), use with caution; no specific guidelines available. |
| Liver impairment | No dose adjustment for mild to moderate hepatic impairment (Child-Pugh A or B). Data lacking for severe impairment (Child-Pugh C); use with caution. |
| Pediatric use | Not FDA-approved for pediatric use. Safety and efficacy not established. |
| Geriatric use | No specific dose adjustment beyond standard adult dosing. Monitor for cholinergic adverse effects (e.g., bradycardia, syncope). Start at 5 mg daily; may increase to 10 mg after 4-6 weeks if tolerated. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other cholinergic agents can have additive effects Can cause nausea vomiting diarrhea and bradycardia.
| Breastfeeding | Excretion into human milk unknown; due to low molecular weight and long half-life (~70 hours), transfer is possible. M/P ratio not established. Caution advised; consider alternative agents or discontinue breastfeeding due to potential for adverse effects in nursing infant (e.g., cholinergic toxicity). |
| Teratogenic Risk | Pregnancy Category C. First trimester: No definitive human data; animal studies show increased fetal resorption and delayed ossification at doses 4-8 times the human AUC. Second and third trimesters: Risk of sustained uterine hypertonicity and fetal bradycardia due to cholinergic stimulation; use only if maternal benefit outweighs potential fetal risk. |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | Common cold Urinary incontinence Rash Nausea Diarrhea Insomnia difficulty in sleeping Weight loss Accidental injury |
| Serious Effects |
["Hypersensitivity to donepezil or piperidine derivatives","History of severe bradycardia or heart block without pacemaker","Active gastrointestinal bleeding"]
| Precautions | ["Risk of bradycardia and syncope due to vagotonic effects","Exacerbation of gastric acid secretion and risk of gastrointestinal bleeding","Risk of urinary obstruction","May cause seizures","May exacerbate asthma or COPD","Risk of neuroleptic malignant syndrome if withdrawn abruptly"] |
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| Fetal Monitoring | Maternal: Monitor for cholinergic adverse effects (bradycardia, hypotension, increased secretions, gastrointestinal disturbances). Fetal: Ultrasound for growth and development; fetal heart rate monitoring if administered near term due to risk of bradycardia. Consider non-stress test or biophysical profile in third trimester. |
| Fertility Effects | In animal studies, no impairment of fertility at doses up to 10 mg/kg/day (approximately 4 times the maximum recommended human dose). Human data lacking; theoretical risk of cholinergic-mediated effects on reproductive function, but no definitive evidence of significant impact. |