Drug Interaction Report

GENERALLY AVOID: Citalopram can cause dose-dependent prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In a randomized, double-blind, crossover, escalating multiple-dose study consisting of 119 healthy subjects, the maximum mean increase in corrected QT interval from placebo was 8.5 msec for citalopram 20 mg and 18.5 msec for citalopram 60 mg. Based on the established exposure-response relationship, prolongation of the corrected QT interval was estimated to be 12.6 ms for citalopram 40 mg. Cases of QT interval prolongation and torsade de pointes have been reported during postmarketing use. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). The extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s). In addition, central nervous system- and/or respiratory-depressant effects may be additively or synergistically increased in patients taking citalopram with certain other drugs that cause these effects, especially in elderly or debilitated patients.

MANAGEMENT: The use of citalopram is not recommended in patients receiving other drugs that prolong the QT interval. Citalopram is also not recommended in patients with congenital long QT syndrome, bradycardia, hypokalemia, hypomagnesemia, recent acute myocardial infarction, or uncompensated heart failure. However, if treatment with citalopram is required in these patients, the labeling recommends that the dosage not exceed 40 mg/day, as higher dosages may have an excessive effect on the QT interval and confer no additional benefit in the treatment of depression. A maximum dosage of 20 mg/day is recommended for patients with hepatic impairment, those greater than 60 years of age, and poor metabolizers of CYP450 2C19. Patients at risk for significant electrolyte disturbances should have serum potassium and magnesium assessed at baseline and periodically during treatment. If hypokalemia or hypomagnesemia is found, it should be corrected prior to initiation of treatment. Regular ECG monitoring is also recommended, and persistent QTc measurements greater than 500 msec should prompt discontinuation of the medication. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. When citalopram is used in combination with other drugs that cause CNS and/or respiratory depression, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression. Ambulatory patients should be counseled to avoid hazardous activities requiring mental alertness and motor coordination until they know how these agents affect them, and to notify their doctor if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Switch to consumer interaction data

MONITOR: Coadministration with methylphenidate may increase the plasma concentrations and effects of selective serotonin reuptake inhibitors (SSRIs). Human pharmacologic studies have shown that methylphenidate may inhibit the metabolism of some antidepressants including SSRIs. There have been isolated reports of adverse reactions such as hallucinations, confusion, seizures, and serotonin syndrome during concomitant use of methylphenidate with an SSRI, which resolved following discontinuation of one or both drugs. Nevertheless, the combination has been used therapeutically to improve clinical response in the treatment of attention-deficit hyperactivity disorder and to augment the effects of SSRIs in the treatment of depression.

MANAGEMENT: Pharmacologic response to SSRIs should be monitored more closely whenever methylphenidate (racemic) or dexmethylphenidate (the more pharmacologically active d-enantiomer) is added to or withdrawn from therapy, and the dosage of one or both drugs adjusted as necessary.

Switch to consumer interaction data

GENERALLY AVOID: Alcohol may exacerbate the adverse central nervous system effects of psychoactive drugs, including methylphenidate.

GENERALLY AVOID: Consumption of alcohol while taking certain sustained-release formulations of methylphenidate may cause rapid release of the drug, resulting in increased systemic levels of methylphenidate. In vitro studies have been conducted using Metadate CD 60 mg and Ritalin LA 40 mg capsules, as well as Concerta 18 mg tablet. At an alcohol concentration of 40%, an increase in the release rate of methylphenidate was observed in the first hour for Metadate CD and Ritalin LA, resulting in 84% and 98% of the methylphenidate being released, respectively. In contrast, there was no increased release of methylphenidate in the first hour for Concerta. These results are considered to be representative of the other available strengths of the corresponding product.

MANAGEMENT: Patients treated with methylphenidate should be advised to avoid alcohol or medications that contain alcohol.

Switch to consumer interaction data

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

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Switch to consumer interaction data