RCK and Alcohol/Food Interactions

Ropivacaine serum concentrations may increase when given with drugs metabolized by the CYP450 isoenzyme 1A2. The theorized mechanism is via competitive inhibition. Information is only available from in-vitro studies. The clinical significance is unknown. Consider monitoring the patient more closely for prolonged or excessive ropivacaine effects if these agents are coadministered.

MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia. Patients should also avoid driving or operating hazardous machinery until they know how the medications affect them.

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

MONITOR: Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.

MANAGEMENT: Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.

NSAIDs - fluid retention

Fluid retention and edema have been reported in association with the use of nonsteroidal anti-inflammatory drugs (NSAIDs), including some topical formulations. NSAIDs (including topicals) can lead to new onset of hypertension or worsening of preexisting hypertension, either of which can contribute to the increased incidence of cardiovascular events. NSAIDs should be used with caution in patients with preexisting fluid retention, hypertension, or history of heart failure. NSAIDs should be avoided in patients with severe heart failure unless the benefits are expected to outweigh the risk of worsening heart failure; if an NSAID is used in such patients, they should be monitored for signs of worsening heart failure. Blood pressure and cardiovascular status should be monitored closely during the initiation of NSAID treatment and throughout the course of therapy.