Labeling Changes and Warnings
Didanosine (Videx):
Bristol-Meyers Squibb Co. (BMS), maker of didanosine, has sent a letter to health care providers noting a change in prescribing information for the drug, a nucleoside analogue reverse transcriptase inhibitor indicated for use in combination with other antiretroviral drugs for the treatment of HIV-1 infection. The change in labeling follows results of a recently completed clinical trial showing that 48-week virologic response in the study arm containing didanosine (once-daily) was significantly lower than that observed in the comparator arm.
Although once daily dosing is available, it should only be considered for adult patients whose management requires once-daily administration of didanosine. Therefore, the preferred dosing frequency of didanosine is twice-daily because there is more evidence to support the effectiveness of that dosing frequency.
Questions may be addressed to BMS at (800) 426-7644.
Divalproex sodium delayed-release tablets (Depakote):
Abbott Pharmaceuticals has mailed a letter to health care professionals advising of an update to the warnings section of labeling for divalproex sodium delayed-release tablets (Depakote Tablets), divalproex sodium coated particles in capsules (Depakote Sprinkle Capsules), and valproate sodium injection (Depacon). Similar changes have been made to the valproic acid capsules and syrup (Depakene). The labeling change consists of the addition of a warning of cases of life-threatening pancreatitis in both children and adults. Some cases have been described as hemorrhagic with rapid progression from initial symptoms to death. Additionally, cases have been reported shortly after initiation of use as well as following several years of use. Caregivers are warned that abdominal pain, nausea, vomiting, and/or anorexia can be symptoms of pancreatitis that require prompt medical evaluation.Questions may be addressed to Abbott at (800) 633-9110.
Thioridazine hydrochloride (Mellaril):
Novartis Pharmaceuticals, maker of Mellaril brand of thioridazine, has sent a letter to doctors and pharmacists advising of important labeling changes for all dosage forms of Mellaril.First, a boxed warning has been added to advise that Mellaril has been shown to prolong the QTc interval in a dose-related manner, and drugs with this potential, including Mellaril, have been associated with torsade de pointes-type arrhythmias and sudden death. Second, Mellaril is now indicated only for schizophrenic patients who fail to show an acceptable response to adequate courses of treatment with other antipsychotic drugs, either because of insufficient effectiveness or the inabil-ity to achieve an effective dose due to intolerable adverse effects.
Third, Mellaril is now contraindicated with certain drugs including fluvoxamine, propranolol, pindolol, any drug that inhibits the cytochrome P450 2D6 isozyme (e.g., fluoxetine and paroxetine), and agents known to prolong the QTc interval. Mellaril also is contraindicated in patients known to have reduced levels of cytochrome P450 2D6 isozyme and in patients with congenital long QT syndrome or a history of cardiac arrhythmias. Fourth, patients considered for therapy with Mellaril should have a baseline ECG performed and serum potassium levels measured. Serum potassium should be normalized prior to starting therapy, and patients with a QTc interval greater than 450 msec should not receive Mellaril.
Fifth, treatment of Mellaril overdosage should include immediate cardiovascular monitoring, including ECG, to detect arrhythmias. Drugs that may produce additive QT-prolonging effects (e.g., disopyramide, procainamide, and quinidine) should be avoided during treatment of Mellaril overdosage.
Questions may be addressed to Novartis at (888) 669-6682.
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