Donepezil tablets for Alzheimer's dementia treatment

Donepezil hydrochloride is a medication used to treat dementia associated with Alzheimer's disease. It is available as oral tablets and is approved for patients with mild, moderate, and severe stages of Alzheimer's dementia. Donepezil works by enhancing brain function through increasing acetylcholine levels, a neurotransmitter important for memory and cognition.

Donepezil tablets are prescribed for the treatment of dementia of the Alzheimer's type in adults. The medication is effective for patients across the spectrum of disease severity:

• Mild to moderate Alzheimer's disease
• Moderate to severe Alzheimer's disease

Donepezil hydrochloride

Donepezil is an acetylcholinesterase inhibitor that works by blocking the enzyme acetylcholinesterase. This inhibition increases the concentration of acetylcholine, a chemical messenger involved in memory and learning, in the brain. By enhancing cholinergic function, donepezil may help improve cognitive symptoms of Alzheimer's disease, although it does not alter the underlying disease progression.

Mild to Moderate Alzheimer's Disease

The recommended starting dose is 5 mg once daily in the evening, just prior to bedtime. After 4 to 6 weeks, the dose may be increased to 10 mg once daily if tolerated. The maximum recommended dose in this group is 10 mg per day.

Moderate to Severe Alzheimer's Disease

Treatment also begins at 5 mg once daily in the evening. After 4 to 6 weeks, the dose can be increased to 10 mg once daily. After at least 3 months on 10 mg daily, the dose may be further increased to 23 mg once daily. The maximum dose in this population is 23 mg per day.

Donepezil tablets can be taken with or without food. Doses should not be escalated until the minimum duration at the prior dose has been completed. The medication should be taken in the evening before going to bed.

Donepezil hydrochloride tablets are contraindicated in patients with known hypersensitivity to donepezil hydrochloride or to piperidine derivatives.

• Anesthesia: Donepezil may exaggerate the effects of succinylcholine-type muscle relaxants during surgery.
• Cardiovascular: It can cause vagotonic effects leading to bradycardia or heart block, even in patients without prior heart conduction issues. Syncope has been reported.
• Nausea and vomiting: Common side effects, more frequent with higher doses (10 mg and 23 mg). These symptoms are often transient but require close monitoring after treatment initiation or dose increase.
• Gastrointestinal bleeding: Cholinesterase inhibitors can increase gastric acid secretion. Patients with a history of ulcers or those on NSAIDs should be monitored for signs of GI bleeding.
• Weight loss: More common with the 23 mg dose; significant weight decreases (≥7%) observed in some patients.
• Bladder obstruction: May worsen symptoms of bladder outflow obstruction.
• Seizures: Donepezil may have the potential to cause generalized convulsions; however, seizures can also be a symptom of Alzheimer's disease itself.
• Respiratory conditions: Caution is advised in patients with asthma or obstructive pulmonary disease due to potential cholinergic effects.

Common adverse reactions

• Nausea
• Diarrhea
• Insomnia
• Vomiting
• Muscle cramps
• Fatigue
• Anorexia

Other reported reactions

• Headache
• Dizziness
• Ecchymosis
• Abnormal dreams
• Depression
• Weight loss
• Urinary symptoms including incontinence and infections
• Syncope
• Hallucinations and confusion
• Seizures (rare)
• Chest pain
• Emotional lability

The incidence of gastrointestinal side effects and discontinuations is higher with increasing dose, especially with the 23 mg dosage.

• Anticholinergic medications: May reduce the effectiveness of donepezil.
• Succinylcholine and similar neuromuscular blockers: Donepezil may enhance muscle relaxation effects, increasing risk during anesthesia.
• Cholinergic agonists (e.g., bethanechol): May have additive effects with donepezil.
• CYP3A4 and CYP2D6 inhibitors (e.g., ketoconazole, quinidine): Can increase donepezil plasma concentrations; clinical relevance is uncertain.
• CYP3A4 inducers (e.g., phenytoin, carbamazepine, rifampin): May increase metabolism and reduce donepezil levels.
• No significant interactions: Formal studies show no considerable effects with theophylline, cimetidine, warfarin, digoxin, or ketoconazole on donepezil kinetics.

Pregnancy

There are no adequate human data on use during pregnancy. Animal studies did not show teratogenic effects during organogenesis but noted increased stillbirths and decreased offspring survival in late pregnancy and lactation at doses comparable to human exposure. The risk of birth defects or miscarriage in humans is unknown.

Lactation

It is unknown whether donepezil or its metabolites are present in human milk, or the effects on breastfed infants. The benefits of breastfeeding should be weighed against the maternal need for donepezil and potential risks to the infant.

Overdose can cause cholinergic crisis characterized by severe nausea, vomiting, salivation, sweating, slow heart rate, low blood pressure, respiratory depression, collapse, convulsions, and muscle weakness which may lead to death if untreated. Management includes general supportive measures and administration of intravenous atropine sulfate, starting with 1.0 to 2.0 mg titrated to clinical response. The effectiveness of dialysis in removal is unknown.

Store donepezil tablets between 20°C to 25°C (68°F to 77°F), with permitted excursions from 15°C to 30°C (59°F to 86°F). Protect from damage—do not use if blister packaging is torn or broken.