Drug Interaction Report

GENERALLY AVOID: Coadministration of omacetaxine and drugs that interfere with platelet function or coagulation may potentiate the risk of bleeding complications. Treatment with omacetaxine is associated with a high frequency of thrombocytopenia. In one study, the overall incidence of grade 3 and 4 thrombocytopenia was 85% and 88%. Fatal cerebral hemorrhages occurred in 2% of patients receiving omacetaxine and nonfatal gastrointestinal hemorrhages occurred in 2%.

MANAGEMENT: Concomitant use of other medications that interfere with platelet function or coagulation should be avoided if the patient's platelet count is less than 50,000 per microliter. Close clinical and laboratory observation for bleeding complications is recommended during therapy. The CBC and platelet count should be monitored according to the manufacturer's recommendations. Patients should be advised to immediately report signs of hemorrhage including unusual bleeding, bruising, blood in the urine or feces, confusion, blurry vision, or slurred speech.

H2 antagonists may alter the pharmacokinetic disposition of some nonsteroidal anti-inflammatory drugs (NSAIDs), resulting in increased or decreased plasma concentrations. Data have been varied, even for the same NSAID. The mechanism may involve inhibition of metabolism, changes in gastric pH resulting in altered absorption, and/or reduced urinary elimination of the affected NSAIDs. Statistically significant changes have been small and of limited clinical significance when interactions have been observed.

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.