Rivastigmine

Pronunciation

Rivastigmine 1.5mg (EXELON 1.5mg)

Rivastigmine 3mg (EXELON 3mg)

Rivastigmine 4.5mg (EXELON 4.5mg)

Introduction

Rivastigmine, 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.

Mechanism of Action

Acetylcholinesterase inhibiting drug

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Rivastigmine Cap 1.5 mg	RIVA01	P1S1S3
Rivastigmine Cap 3 mg	RIVA02	P1S1S3
Rivastigmine Cap 6 mg	RIVA04	P1S1S3

Dosage

The drug can be administered orally or via a transdermal patch; the latter form reduces the prevalence of side effects, which typically include nausea and vomiting.

By Oral: initially 1.5 mg twice daily, increased in steps of 1.5 mg twice daily at intervals of at least 2 weeks according to response and tolerance. Usual range 3-6 mg twice daily. Maximum 6 mg twice daily. If treatment interrupted for more than several days, treatment should be retitrated from 1.5 mg twice daily.

Transdermal patches delivering 4.6, 9.5, or 13.3 mg of rivastigmine over 24 hours are also available for once-daily application.

Transdermal application: initially apply 4.6 mg/24 hours patch to clean, dry, non-hairy, non-irritated skin on back, upper arm, or chest, removing after 24 hours. It should not be applied to the abdomen or thigh due to decreased bioavailability. Re-application to the same site should be avoided for 14 days. Only one patch should be applied at a time.

If well tolerated, increase to 9.5 mg/24 hours patch daily.

After a further 6 months if well tolerated and cognitive deterioration or functional decline are shown, the dose can be increased to 13.3 mg/24 hours patch daily.

However, for patients with a body weight below 50 kg, a maintenance dose of 4.6 mg/24 hours daily may be sufficient.

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.

Clinical benefit should be assessed on a regular basis.

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=

Significant gastrointestinal side effects include

• Nausea and vomiting
• Loss of appetite
• Weight loss
• Diarrhea

Serious side effects may include:

• Abnormal heart rhythms
• Difficulty emptying urine from the bladder
• seizures

Pharmacokinetics

Oral bioavailability	Donepezil hydrochloride is rapidly and well absorbed from the gastrointestinal tract. Plasma protein binding is about 40%.
Onset of action	Peak plasma levels in about one hour after ingestion. Absorption from transdermal patches is slow and peak plasma concentrations are reached in 10 to 16 hours after applying the first patch; with subsequent patches, peak concentrations are reached in about 8 hours.
Metabolism	Primarily metabolized through hydrolysis. Minimal metabolism occurs via the cytochrome P450.
Elimination half-life	1.5 hours after oral doses and about 3 hours after patch removal.