Diclofenacinteractions

See Table 1 for clinically significant drug interactions with diclofenac and misoprostol.

Table 1: Clinically Significant Drug Interactions with Diclofenac and Misoprostol Drugs That Interfere with Hemostasis Clinical Impact: Diclofenac and anticoagulants such as warfarin have a synergistic effect on bleeding. The concomitant use of diclofenac and anticoagulants have an increased risk of serious bleeding compared to the use of either drug alone. Serotonin release by platelets plays an important role in hemostasis. Case-control and cohort epidemiological studies showed that concomitant use of drugs that interfere with serotonin reuptake and an NSAID may potentiate the risk of bleeding more than an NSAID alone.

Intervention: Monitor patients with concomitant use of diclofenac sodium and misoprostol delayed-release tablets with anticoagulants (e.g., warfarin), antiplatelet drugs (e.g., aspirin), SSRIs, and SNRIs for signs of bleeding.

Aspirin Clinical Impact: Controlled clinical studies showed that the concomitant use of NSAIDs and analgesic doses of aspirin does not produce any greater therapeutic effect than the use of NSAIDs alone. In a clinical study, the concomitant use of an NSAID and aspirin was associated with a significantly increased incidence of GI adverse reactions as compared to use of the NSAID alone.

Intervention: Concomitant use of diclofenac sodium and misoprostol delayed-release tablets and analgesic doses of aspirin is not generally recommended because of the increased risk of bleeding. Diclofenac sodium and misoprostol delayed-release tablets are not a substitute for low dose aspirin for cardiovascular protection. ACE Inhibitors, Angiotensin Receptor Blockers, and Beta-Blockers Clinical Impact: NSAIDs may diminish the antihypertensive effect of ACE inhibitors, ARBs, or beta-blockers (including propranolol). In patients who are elderly, volume-depleted (including those on diuretic therapy), or have renal impairment, co-administration of an NSAID with ACE inhibitors or ARBs may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible.

Intervention: The concomitant administration of these drugs should be done with caution. Patients should be adequately hydrated and the clinical need to monitor the renal function should be assessed at the beginning of the concomitant treatment and periodically thereafter. During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and ACE inhibitors, ARBs, or beta-blockers, monitor blood pressure to ensure that the desired blood pressure is obtained. During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and ACE inhibitors or ARBs in patients who are elderly, volume-depleted, or have impaired renal function, monitor for signs of worsening renal function.

Diuretics Clinical Impact: Clinical studies, as well as post-marketing observations, showed that NSAIDs reduced the natriuretic effect of loop diuretics (e.g., furosemide) and thiazide diuretics in some patients. This effect has been attributed to the NSAID inhibition of renal prostaglandin synthesis.

Intervention: During concomitant use of diclofenac sodium and misoprostol delayed-release tablets with diuretics, observe patients for signs of worsening renal function, in addition to assuring diuretic efficacy including antihypertensive effects.

Digoxin Clinical Impact: The concomitant use of diclofenac with digoxin has been reported to increase the serum concentration and prolong the half-life of digoxin.

Intervention: During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and digoxin, monitor serum digoxin levels.

Lithium Clinical Impact: NSAIDs have produced elevations in plasma lithium levels and reductions in renal lithium clearance. The mean minimum lithium concentration increased 15%, and the renal clearance decreased by approximately 20%. This effect has been attributed to NSAID inhibition of renal prostaglandin synthesis.

Intervention: During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and lithium, monitor patients for signs of lithium toxicity.

Methotrexate Clinical Impact: Concomitant use of NSAIDs and methotrexate may increase the risk for methotrexate toxicity (e.g., neutropenia, thrombocytopenia, renal dysfunction).

Intervention: During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and methotrexate, monitor patients for methotrexate toxicity.

Cyclosporine Clinical Impact: Concomitant use of diclofenac and cyclosporine may increase cyclosporine’s nephrotoxicity.

Intervention: During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and cyclosporine, monitor patients for signs of worsening renal function. NSAIDs and Salicylates Clinical Impact: Concomitant use of diclofenac with other NSAIDs or salicylates (e.g., diflunisal, salsalate) increases the risk of GI toxicity, with little or no increase in efficacy.

Intervention: The concomitant use of diclofenac sodium and misoprostol delayed-release tablets with other NSAIDs or salicylates is not recommended.

Pemetrexed Clinical Impact: Concomitant use of diclofenac and pemetrexed may increase the risk of pemetrexed-associated myelosuppression, renal, and GI toxicity (see the pemetrexed prescribing information).

Intervention: During concomitant use of diclofenac sodium and misoprostol delayed-release tablets and pemetrexed, in patients with renal impairment whose creatinine clearance ranges from 45 to 79 mL/min, monitor for myelosuppression, renal and GI toxicity. Avoid diclofenac sodium and misoprostol delayed-release tablets for a period of two days before, the day of, and two days following administration of pemetrexed.

Antacids Clinical Impact: Antacids reduce the bioavailability of misoprostol acid. Antacids may also delay absorption of diclofenac. Magnesium-containing antacids exacerbate misoprostol-associated diarrhea.

Intervention: Concomitant use of diclofenac sodium and misoprostol delayed-release tablets and magnesium-containing antacids is not recommended.

Corticosteroids Clinical Impact: Concomitant use of corticosteroids with diclofenac may increase the risk of GI ulceration or bleeding.

Intervention: Monitor patients with concomitant use of diclofenac sodium and misoprostol delayed-release tablets with corticosteroids for signs of bleeding. CYP2C9 Inhibitors or Inducers Clinical Impact: Diclofenac is metabolized by cytochrome P450 enzymes, predominantly by CYP2C9. Co-administration of diclofenac with CYP2C9 inhibitors (e.g., voriconzaole) may enhance the exposure and toxicity of diclofenac whereas co-administration with CYP2C9 inducers (e.g., rifampin) may lead to compromised efficacy of diclofenac.

Intervention: CYP2C9 inhibitors: When concomitant use of CYP2C9 inhibitors is necessary, the total daily dose of diclofenac should not exceed the lowest recommended dose of diclofenac sodium and misoprostol delayed-release tablets, 50 mg/200 mcg twice daily.

CYP2C9 inducers: A dosage adjustment may be warranted when diclofenac sodium and misoprostol delayed-release tablets are administered with CYP2C9 inducers. Administer the separate products of misoprostol and diclofenac if a higher dose of diclofenac is deemed necessary. See full prescribing information for a list of clinically important drug interactions.