Drugs To Treat Alzheimer's Disease

Question 1

Donepezil

Answer 1

Indication
Alzheimer’s disease

Precaution
Risk of prolonged QTc interval & torsades de pointed

Dose: oral initially 5mg of for a min of 4 weeks , increase to 10mg od according to clinical response

Practice points

Dose of 10mg od has more benefit than 5mg but increases risk of ADR

Donepezil is usually given in the evening but consider giving it in the morning if it is more convenient or insomnia or vivid dreams occurs with night time dosing

Question 2

Galantamine

Answer 2

Indication: mild to moderate Alzheimer’s disease

Precaution
Reduce clearance in renal impairment. CI if clcr less than 10ml/min

Dosage: oral initially 8mg od in the morning for a min of 4 weeks then 16mg od in the morning for a min of 4 weeks max 24mg od

Moderate hepatic impairment
Initially 8mg every other morning for 1 week then 8mg once daily in the morning for min 4 weeks, max 16mg od

Counseling
Take with food

Question 3

Rivarastigmine

Answer 3

Indication: Alzheimer’s disease

Precaution: Hepatic -CI in severe impairment due to lack of data

Adr common: patch: skin reactions at injection site

Dosage
Oral: initially 1.5mg be then increase by 3mg od q 2 weeks to a max 6mg bd

Patch: initially 1 patch (4.6mg/24hrs) applied once daily if tolerated increase after 4 weeks to 1 patch (9.5mg/24hours) once daily. If necessary, after at least 4 weeks increase to 1 patch (13.3mg/24 hours) once daily
Conversion from capsules to patch: use patch of the closest strength to establish oral daily dose.

Counseling
Capsule: Take with morning and evening meals

Patch: apply to dry, clean and hairless skin on the back, upper arm or chest. When changing the patch , gently remove the old patch and apply a new one to a different place (avoid reusing the same area for 2 weeks. The patch maybe suitable for pts intolerant of oral therapy. Nausea and vomitting are less common in patch than with oral rivarastigmine

Question 4

Memantine

Answer 4

Moa: N-methyl-D-aspartate(NMDA) antagonist may reduce glutamate induced neuronal degradation. Alzheimer’s disease is thought to be associated with excess glutamate

Indication: moderate to severe Alzheimer’s disease

Precautions: history of seizures-contraindicated

Renal-clearance of memantine is reduced in renal impairment, reduce dose if clcr is less than 30ml/min

Adr
Common: confusion, dizziness, drowsiness, headache, insomnia, agitation, hallucinations, dyspnoea, hypersensitivity

Dosage: oral initially 5mg in the morning, increase by 5mg od each week if tolerated to a maintenance dose of 20ng od

Renal impairment:
Clcr:5-29ml/min maintenance dose 10mg od

Counseling: This medicine may make you feel drowsy or dizzy. Avoid operate machinery

Practice points

-memantine maybe associated with modest reduction in clinical deterioration associated with Alzheimer’s disease

-tx should be started by a specialist

• regular review if behavioural and functional status is important