Drug Interaction Report

MONITOR: Delirium has been observed during the coadministration of benztropine and selective serotonin reuptake inhibitors (SSRIs). The mechanism of this potential interaction, if any, has not been determined. There have only been isolated case reports, and concomitant neuroleptic use was common.

MANAGEMENT: Until further data are available, it may be appropriate to monitor patients for evidence of delirium or other unusual psychiatric reactions when benztropine is given with SSRIs, especially if neuroleptic therapy is also administered.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of vilazodone. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of vilazodone. According to the product labeling, vilazodone blood concentrations in the fasted state can be decreased by approximately 50% compared to the fed state, which may result in diminished effectiveness in some patients. The absolute bioavailability of vilazodone is 72% with food. In study subjects, administration with food (high-fat or light meal) increased vilazodone peak plasma concentration (Cmax) by approximately 147% to 160% and systemic exposure (AUC) by approximately 64% to 85%.

MANAGEMENT: Patients receiving vilazodone should be advised to avoid consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how vilazodone affects them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities. Vilazodone should be taken with food. Administration without food may result in inadequate drug concentrations and diminished effectiveness.

GENERALLY AVOID: Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.

MANAGEMENT: Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.