Pharmacokinetic rationale for the rivastigmine patch.

The dual cholinesterase inhibitor rivastigmine is approved in capsule form in many countries for the symptomatic treatment of dementia associated with Alzheimer disease (AD) and Parkinson disease (PD). All orally administered cholinesterase inhibitors are associated with central cholinergic gastrointestinal side effects, particularly during the titration phase, which are believed to be caused by a rapid increase in brain acetylcholine levels after effective inhibition of the target enzymes. A recently developed rivastigmine transdermal patch may have the potential to reduce such side effects. Pharmacokinetic studies have shown that transdermal administration of rivastigmine prolongs t(max), lowers C(max), and reduces fluctuations in plasma concentration. The 10-cm(2) rivastigmine patch provides comparable exposure (area under the curve, AUC) to the highest capsule dose (6-mg BID) and may be the target maintenance dose for most patients, delivering optimal rivastigmine exposure to produce a therapeutic effect. The potential of a patch to improve the tolerability of rivastigmine (e.g., nausea and vomiting) while permitting similar exposure to the highest doses of capsules may, in turn, lead to improved efficacy and compliance.