Rivastigmine

Antidementia Drug

Drug class: Acetylcholinesterase Inhibitor

Rivastigmine (EXELON) (中文: 利凡斯的明) is a reversible acetylcholinesterase inhibitor. Rivastigmine is selective for the CNS and is used for the treatment of mild to moderate dementia associated with Parkinson’s disease.

Pronunciation

Rivastigmine 1.5mg (EXELON 1.5mg)

Rivastigmine 3mg (EXELON 3mg)

Rivastigmine 4.5mg (EXELON 4.5mg)

Common Strengths

• Oral Capsules: 1.5 mg, 3 mg, 4.5 mg, 6 mg
• Transdermal Patches: 4.6 mg/24 hours, 9.5 mg/24 hours, 13.3/24 hour

Drug Trade Names

• Exelon

Drug Usage

For managing symptoms of dementia, improving cognitive function and daily living activities in affected individuals. It is not a cure but may help slow the progression of symptoms.

Mechanism of Action

Rivastigmine works by inhibiting acetylcholinesterase, the enzyme responsible for breaking down acetylcholine in the brain. This inhibition leads to increased level of acetylcholine, which is crucial for memory and cognitive function.

Route of Administration

Rivastigmine can be administered:

• Orally (capsules)
• Transdermally (patch)

Dosage

• Initial: 1.5 mg orally twice daily; may increase every two weeks up to a maximum of 6 mg twice daily.
• Transdermal: Start with a patch delivering 4.6 mg/24 hours, with potential increases based on tolerance.

Conversion of oral rivastigmine to patches are as follows

• Those taking ≤6 mg daily of oral rivastigmine may be switched to 4.6 mg/24 hours patch.
• Those taking more than 6 mg daily may be switched to 9.5 mg/24 hours patch.
• The first patch should be applied on the day following the last oral dose.

How quickly dose Rivastigmine patch work?

Rivastigmine may take as long as 12 weeks to begin working and individual response to this medication will vary.

Side Effects

Frequency	Adverse reactions
Common Side Effects	Nausea
	Vomiting
	Loss of appetite
	Diarrhea
	Dizziness
Serious Side Effects	Sever allergic reactions (e.g. difficulty greathing)
	Seizures
	Involuntary movement or tremors

Pharmacokinetics

It is available in two primary formulations: capsules and transdermal patches. The pharmacokinetics of these two forms differ significantly

• The transdermal patch provides a continuous release of rivastigmine over 24 hours, leading to a smoother pharmacokinetic profile with lower peak plasma concentrations compared to oral capsules.
• The patches are designed to minimize fluctuations in drug levels, which can enhance tolerability and compliance among patients.

Summary of Key Differences

Feature	Capsules	Transdermal Patch
Absorptions Peak Time	~1 hour	Continuous over 24 hours
Elimination half-life	~1 hour	~1 hour
Dosing Flexibility	Requires titration	Steady release

In conclusion, both formulations of rivastigmine serve important roles in managing dementia symptoms but differ significantly in their pharmacokinetic profiles. The transdermal patch offers advantages in terms of steady drug delivery and reduced side effects compared to oral administration.

Drug Precautions

Pregnancy

The safety of rivastigmine during pregnancy has not been established.

Breastfeeding

Rivastigmine should generally not be used by nursing mothers unless the benefits outweigh potential risks.

Children and Elderly

• Children: Safety and efficacy in children have not been established
• Elderly: Generally well-tolerated; however, lower starting doses may be considered due to increased sensitivity to side effects.

Hepatic Impairment

Titrate according to individual tolerability in mild to moderate impairment; use with caution in severe impairment.

Renal Impairment

Titrate according to individual tolerability.

Drug Monitoring Items

Monitoring should include:

• Cognitive function assessments (e.g. MoCA)
• Monitoring for gastrointestinal side effects (nausea, vomiting)
• Regular evaluation of heart rate and blood pressure due to potential bradycardia
• Regular monitoring of weight is important, as patients may experience weight loss while on rivastigmine

Drug Interactions

Rivastigmine has low potential for drug-drug interactions but should be used cautiously with:

• Beta-blockers: can affect heart rate and rhythm
• Other cholinergic agents
• Medications affecting gastrointestinal motility (e.g. metoclopramide may increase extrapyramidal side effects.)

Caution

• Cardiovascular conduction disorders such as sick-sinus syndrome
• Susceptibility to peptic ulcers
• Asthma, chronic obstructive pulmonary disease
• People who have a predisposition to seizures
• Concomitant antipsychotic treatment – increased risk of neuroleptic malignant syndrome

Contraindications

Patients with known hypersensitivity to rivastigmine.

FAQ

How Should I Take the Tablet?

Take rivastigmine capsules twice daily with meals to reduce gastrointestinal side effects.

What Should I Avoid While Taking?

Avoid alcohol and medications that can cause sedation or affect alertness until you know how rivastigmine affects you.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember unless it is almost time for your next dose. Do not double up on doses.