Pharmacokinetic rationale for the rivastigmine patch
ABSTRACT 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.
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ABSTRACT: Alzheimer's disease and Parkinson's disease dementia are becoming a public health issue. Given the therapeutic pitfalls in the elderly, there is a need of effective therapies. Rivastigmine, a cholinesterase inhibitor, emerges as an important agent in the symptomatic treatment of dementia. The efficacy of this drug has been shown in several studies, being now included in the guidelines for dementia management. The new matrix rivastigmine patch represents a step forward in managing the elderly patient with dementia. The IDEAL (Investigation of Transdermal Exelon in Alzheimer's disease) study demonstrates the superiority of the transdermal rivastigmine patch over capsules, proving an increased tolerability and compliance for the 9.5 mg/24 h rivastigmine patch in patients with Alzheimer's disease. The transdermal patch with rivastigmine may offer additional therapeutic benefits and may prove to be the best delivery system for this drug to treat Alzheimer's disease. The benefits of rivastigmine in dementia associated with Parkinson's disease have been shown by a smaller study, using the oral formula, but a study using rivastigmine patch is still lacking. The new technological developments in drug delivery may change our view in managing patients, improving their adherence to therapy and better results.
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ABSTRACT: In this paper, a design procedure and successful experimental results obtained from it are reported for implementing internally compensated operational amplifiers powered from a single power supply and with high gain-bandwidth product, good slew-rate, low output impedance and good drive levels. The procedure was developed for an in-house training course on “analog integrated circuit design” as an example of using mathematical tools (MathCad) in the design of analog integrated circuit blocks. The resulting MathCad file became a design automation tool for CMOS opamp design. It is shown that all opamp specs targeted are met or exceeded by the sample opamp designed and fabricated using Fairchild Semiconductor's CS80C CMOS process with the W/L ratios predicted by this toolUniversity/Government/Industry Microelectronics Symposium, 2001. Proceedings of the Fourteenth Biennial; 02/2001