Drug Interactions between citalopram and Mepergan Fortis

Using meperidine together with citalopram can increase the risk of a rare but serious condition called the serotonin syndrome, which may include symptoms such as confusion, hallucination, seizure, extreme changes in blood pressure, increased heart rate, fever, excessive sweating, shivering or shaking, blurred vision, muscle spasm or stiffness, tremor, incoordination, stomach cramp, nausea, vomiting, and diarrhea. Severe cases may result in coma and even death. You should seek immediate medical attention if you experience these symptoms while taking the medications. Talk to your doctor if you have any questions or concerns. Your doctor may already be aware of the risks, but has determined that this is the best course of treatment for you and has taken appropriate precautions and is monitoring you closely for any potential complications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

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. The maximum mean difference from placebo in the individually corrected QTc (QTcNi) interval for healthy subjects (n=119) evaluated in a randomized, double-blind, crossover, escalating multiple-dose study for citalopram (20 mg/day for 9 days, 40 mg/day for 4 days, and then 60 mg/day for 9 days) was 8.5 msec for 20 mg and 18.5 msec for 60 mg. Based on the established exposure-response relationship, prolongation of the QTcNi interval was estimated to be 12.6 msec for citalopram 40 mg. Cases of QT prolongation and ventricular arrhythmia including torsade de pointes have been reported during postmarketing use, predominantly in patients of female gender, with hypokalemia, or with preexisting QT-prolongation or other cardiac disease. 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 those noted in postmarketing use with citalopram. The extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s). In addition, when two or more medications with similar adverse effect profiles are given concurrently, the likelihood of experiencing these adverse reactions may be increased. For example, the risk of experiencing central nervous system (CNS) and/or respiratory depressant effects may be increased when citalopram is combined with another agent that could also cause these adverse reactions, particularly in those who are already at an increased risk, such as the elderly or debilitated patients.

MANAGEMENT: The use of citalopram is not recommended in patients receiving other drugs that prolong the QT interval and is considered contraindicated by some authorities. Likewise, citalopram should be avoided in patients with congenital long QT syndrome, bradycardia, hypokalemia, hypomagnesemia, recent acute myocardial infarction, or uncompensated heart failure unless the benefits outweigh the risks for a particular patient. If treatment with citalopram is considered clinically necessary or beneficial in these patients, the labeling recommends that the dosage not exceed 40 mg/day, unless the patient has hepatic impairment, is greater than 60 years of age, and/or is a poor metabolizer of CYP450 2C19 in which case the dosage should not exceed 20 mg/day. 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 and periodically monitored. Regular ECG monitoring is also advised, and persistent QTc measurements greater than 500 msec should prompt discontinuation of the medication(s). 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. Additionally, 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. The product labeling of the concomitant medication should be consulted for further guidance, such as specific dosage adjustment and/or management recommendations should serious adverse reactions occur.

Using meperidine together with promethazine may increase side effects such as drowsiness, dizziness, lightheadedness, confusion, depression, low blood pressure, slow or shallow breathing, and impairment in thinking, judgment, and motor coordination. Occasionally, severe reactions may result in coma and even death. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. You should avoid the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you, and use caution when getting up from a sitting or lying position. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.