Drug Interactions between Meprozine and propofol

ADJUST DOSE: The central nervous system and respiratory depressant effects of meperidine may be potentiated by concomitant use of other agents with CNS depressant effects. An increased risk of serious adverse reactions such as respiratory depression, hypotension, profound sedation, syncope, coma, and even death should be considered, particularly in elderly or debilitated patients.

MANAGEMENT: Caution and dosage adjustments are advisable when meperidine is used in combination with other narcotic analgesics, general anesthetics, phenothiazines, sedative-hypnotics, tranquilizers, tricyclic antidepressants, or other CNS depressants such as alcohol. A lower dosage of meperidine should be considered initially, then titrated carefully according to pain level and clinical response. Meperidine dosage reductions of 25% to 50% have been recommended for patients receiving phenothiazines and other tranquilizers. Patients should be advised to avoid rising abruptly from a sitting or recumbent position, and to notify their physician if they experience dizziness, lightheadedness, orthostasis, syncope, tachycardia, or excessive CNS effects that interfere with their normal activities. Patients should also avoid driving or operating hazardous machinery until they know how these medications affect them.

MONITOR: Additive central nervous system and cardiorespiratory depressant effects may occur when fospropofol or propofol is administered with other depressants such as sedative-hypnotic agents and narcotic analgesics.

MANAGEMENT: Patients should be monitored closely for excessive sedation and cardiorespiratory depression, and the medication dosage(s) adjusted accordingly. Supportive therapy should be provided if needed.

MONITOR: Treatment with propofol may lead to prolongation of the QT interval; however, the extent of prolongation and its clinical impact is difficult to determine. A retrospective single-center cohort study in patients treated at the Mayo clinic over 17 years (n=628,784) concluded that torsade de pointes (TdP) after propofol administration occurred at an annual incidence of 1.93 per million; however, it was often associated with other risk factors, including concomitant QT-prolonging medications, low serum potassium levels (<3.5 mmol/L), and low serum magnesium levels (<1.8 mg/dL). Other studies have reported that propofol has no effect or that it decreases the QTc interval and may offset QTc prolongation due to other coadministered anesthetic medications. Theoretically, concurrent use of two or more drugs that can cause QT interval prolongation may result in additive effects and increased risk of ventricular arrhythmias including TdP and sudden death. The risk of an individual agent or a combination of these 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). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drugs. Data from formal QT/QTc studies on propofol are lacking.

MANAGEMENT: Caution and clinical monitoring is recommended if propofol is used concomitantly with other agents associated with QT interval prolongation. 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.