Psychiatr News August 17, 2007
Volume 42, Number 16, page 15
© 2007 American Psychiatric Association
FDA Approves Transdermal Patch for Alzheimer's, Parkinson's Dementia
Jun Yan
A new skin patch could make it easier for Alzheimer patients and
caregivers to take rivastigmine treatment.
A topical patch that delivers rivastigmine through the skin has been
approved by the U.S. Food and Drug Administration (FDA) for the treatment of
mild to moderate Alzheimer's disease and for treatment of mild to moderate
dementia associated with Parkinson's disease. Rivastigmine, a reversible
cholinesterase inhibitor, slows the breakdown of the neurotransmitter
acetylcholine in the brain to prolong the cholinergic function. The patches
will be available in the U.S. soon, according to Novartis, maker of the
patch.
The FDA approval of rivastigmine transdermal system (Exelon Patch) is based
on results from a randomized, double-blind, controlled clinical trial that
compared the rivastigmine transdermal system with rivastigmine oral capsules
and placebo. Nearly 1,200 patients with diagnosed Alzheimer's disease were
given two doses of rivastigmine patches (9.5 mg/day or 17.4 mg/day),
rivastigmine 6 mg oral capsule twice daily, or placebo for 24 weeks. The 9.5
mg/day patch resulted in similar efficacy as the 6 mg twice daily oral
dose.
The oral formulations (capsules and solution) of rivastigmine tartrate have
been marketed since 2000 and carry the same FDA-approved indications. The new
transdermal formulation has the advantage of less fluctuation in absorption
and plasma concentration, visual assurance of treatment compliance, and
convenience for patients with difficulty swallowing—a symptom not
unusual in Alzheimer's disease and Parkinson's disease.
Rivastigmine patches are supplied at two strengths, 4.6 mg and 9.5 mg, for
once-daily dosing. For patients who are not on oral rivastigmine capsules or
on a total daily dose of less than 6 mg, the recommended initial dose for the
patch is one 4.6 mg patch a day, which may be increased to one 9.5 mg patch a
day if the patient tolerates the lower dose for at least four weeks. Dose
increase should be done with caution in patients with very low body weight
because of elevated drug levels in the bloodstream. Patients who have been on
oral doses 6 mg or more a day can be directly switched to the 9.5 mg patch.
Rivastigmine patches should be applied once every 24 hours to a clean, dry,
hairless, intact skin area, preferably on the upper or lower back to avoid
being rubbed off or removed by the patient. The application sites should be
rotated to minimize irritation.
Rivastigmine in the patch is absorbed through the skin. The plasma
concentration peaks about eight hours after a patch is applied and then slowly
declines.
Adverse reactions to rivastigmine patches are similar to those of the oral
formulations. The most frequent reactions involve the gastrointestinal,
cardiovascular, and neurological systems. In the clinical study, the most
common adverse events included nausea, vomiting, diarrhea, depression,
headache, anxiety, decreased appetite, and weight loss. Mild to moderate skin
reaction to the patch application may occur. The drug is contraindicated in
patients with hypersensitivity to rivastigmine, other carbamate derivatives,
or any ingredient in the formulation.
Novartis announced on July 19 that the Committee for Medicinal Products for
Human Use has recommended the approval of the rivastigmine transdermal system
in the European Union for mild to moderate Alzheimer's disease.
FDA-approved rivastigmine transdermal system label information is
posted at
<www.fda.gov/cder/foi/label/2007/022083lbl.pdf>.
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