Drug Interaction Report

MONITOR: Additive or synergistic effects on blood pressure and heart rate may occur when serotonin-norepinephrine reuptake inhibitors (SNRIs) are combined with sympathomimetic agents such as nasal decongestants, adrenergic bronchodilators, ophthalmic vasoconstrictors, and systemic vasopressors. The use of SNRIs alone has been associated with sustained increases in blood pressure and heart rate, and cases of elevated blood pressure requiring immediate treatment have been reported in postmarketing experience.

MANAGEMENT: Caution is advised if SNRIs are used with other drugs that can increase blood pressure and/or heart rate. Blood pressure and pulse should be measured prior to initiating SNRI therapy and monitored at regular intervals thereafter. Dose reduction or discontinuation of the SNRI should be considered in patients who experience a sustained increase in blood pressure or pulse rate.

GENERALLY AVOID: Use of milnacipran in conjunction with chronic alcohol consumption may potentiate the risk of liver injury. Milnacipran alone can increase serum transaminase levels. In placebo-controlled fibromyalgia trials, increases in ALT were more frequently observed in patients treated with milnacipran 100 mg/day (6%) and 200 mg/day (7%) compared to patients treated with placebo (3%). One patient receiving milnacipran 100 mg/day (0.2%) had an increase in ALT greater than 5 times the upper limit of normal (ULN) but did not exceed 10 times the ULN. Increases in AST were also more frequently observed in patients treated with milnacipran 100 mg/day (3%) and 200 mg/day (5%) than in patients treated with placebo (2%). There have been reported cases of increased liver enzymes and severe liver injury, including fulminant hepatitis, from foreign postmarketing experience with milnacipran. Significant underlying clinical conditions and/or use of multiple concomitant medications were present in the cases of severe liver injury.

MANAGEMENT: Due to the risk of liver injury, patients prescribed milnacipran should be counseled to avoid excessive use of alcohol. Milnacipran should generally not be prescribed to patients with substantial alcohol use.