Novartis Advises Caution in Restarting Rivastigmine Therapy
Clinicians should use the lowest dosage of rivastigmine when restarting therapy in patients, advised Novartis Pharmaceuticals Corp. in a "Dear Health Care Provider" letter dated Jan. 26.
The company noted that one patient, whose rivastigmine therapy had been interrupted for eight weeks, suffered severe vomiting with esophageal rupture after receiving a single 4.5-mg dose. During controlled trials of the drug, severe vomiting occurred in 2 percent of the patients. The drug, known by the brand name Exelon and marketed in the United States since April 2000, is used in the treatment of mild to moderate dementia of the Alzheimer's type.
According to the package insert (PDF), the starting dosage is 1.5 mg twice daily. This twice-daily dose can be increased gradually, in 1.5-mg increments, no more often than every two weeks, up to a maximum dosage of 6 mg twice daily. Guidelines for restarting rivastigmine therapy have been added to the package insert, along with new warnings and precautions.
The company said that it has little information on the consequences of restarting rivastigmine at dosages higher than the recommended starting dose.