Indomethacininteractions

See Table 2 for clinically significant drug interactions with indomethacin. Table 2 Clinically Significant Drug Interactions with Indomethacin Drugs That Interfere with Hemostasis Clinical Impact: Indomethacin and anticoagulants such as warfarin have a synergistic effect on bleeding. The concomitant use of indomethacin 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 indomethacin capsules with anticoagulants (e.g., warfarin), antiplatelet agents (e.g., aspirin), selective serotonin reuptake inhibitors (SSRIs), and serotonin norepinephrine reuptake inhibitors (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 indomethacin capsules and analgesic doses of aspirin is not generally recommended because of the increased risk of bleeding. Indomethacin capsules are not 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 angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (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: During concomitant use of indomethacin capsules and ACE-inhibitors, ARBs, or beta-blockers, monitor blood pressure to ensure that the desired blood pressure is obtained. During concomitant use of indomethacin capsules and ACE-inhibitors or ARBs in patients who are elderly, volume-depleted, or have impaired renal function, monitor for signs of worsening renal function. When these drugs are administered concomitantly, patients should be adequately hydrated. Assess renal function at the beginning of the concomitant treatment and periodically thereafter.

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. It has been reported that the addition of triamterene to a maintenance schedule of indomethacin capsules resulted in reversible acute renal failure in two of four healthy volunteers. Indomethacin capsules and triamterene should not be administered together. Both indomethacin capsules and potassium-sparing diuretics may be associated with increased serum potassium levels. The potential effects of indomethacin capsules and potassium-sparing diuretics on potassium levels and renal function should be considered when these agents are administered concurrently.

Intervention: Indomethacin and triamterene should not be administered together. During concomitant use of indomethacin capsules with diuretics, observe patients for signs of worsening renal function, in addition to assuring diuretic efficacy including antihypertensive effects. Be aware that indomethacin and potassium-sparing diuretics may both be associated with increased serum potassium levels.

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

Intervention: During concomitant use of indomethacin capsules 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 indomethacin capsules 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 indomethacin capsules and methotrexate, monitor patients for methotrexate toxicity.

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

Intervention: During concomitant use of indomethacin capsules and cyclosporine, monitor patients for signs of worsening renal function. NSAIDs and Salicylates Clinical Impact: Concomitant use of indomethacin with other NSAIDs or salicylates (e.g., diflunisal, salsalate) increases the risk of GI toxicity, with little or no increase in efficacy. Combined use with diflunisal may be particularly hazardous because diflunisal causes significantly higher plasma levels of indomethacin. In some patients, combined use of indomethacin and diflunisal has been associated with fatal gastrointestinal hemorrhage.

Intervention: The concomitant use of indomethacin with other NSAIDs or salicylates, especially diflunisal, is not recommended.

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

Intervention: During concomitant use of indomethacin capsules and pemetrexed, in patients with renal impairment whose creatinine clearance ranges from 45 to 79 mL/min, monitor for myelosuppression, renal and GI toxicity. NSAIDs with short elimination half-lives (e.g., diclofenac, indomethacin) should be avoided for a period of two days before, the day of, and two days following administration of pemetrexed. In the absence of data regarding potential interaction between pemetrexed and NSAIDs with longer half-lives (e.g., meloxicam, nabumetone), patients taking these NSAIDs should interrupt dosing for at least five days before, the day of, and two days following pemetrexed administration.

Probenecid Clinical Impact: When indomethacin is given to patients receiving probenecid, the plasma levels of indomethacin are likely to be increased.

Intervention: During the concomitant use of indomethacin capsules and probenecid, a lower total daily dosage of indomethacin may produce a satisfactory therapeutic effect. When increases in the dose of indomethacin are made, they should be made carefully and in small increments. Drugs that Interfere with Hemostasis (e.g. warfarin, aspirin, SSRIs/SNRIs): Monitor patients for bleeding who are concomitantly taking indomethacin capsules with drugs that interfere with hemostasis. Concomitant use of indomethacin and analgesic doses of aspirin is not generally recommended. ACE Inhibitors, Angiotensin Receptor Blockers (ARB), or Beta-Blockers: Concomitant use with indomethacin may diminish the antihypertensive effect of these drugs. Monitor blood pressure.

ACE Inhibitors and ARBs: Concomitant use with indomethacin in elderly, volume depleted, or those with renal impairment may result in deterioration of renal function. In such high risk patients, monitor for signs of worsening renal function.

Diuretics: NSAIDs can reduce natriuretic effect of furosemide and thiazide diuretics. Monitor patients to assure diuretic efficacy including antihypertensive effects.

Digoxin: Concomitant use with indomethacin can increase serum concentration and prolong half-life of digoxin. Monitor serum digoxin levels. Effects on Laboratory Tests Indomethacin capsules reduces basal plasma renin activity (PRA), as well as those elevations of PRA induced by furosemide administration, or salt or volume depletion. These facts should be considered when evaluating plasma renin activity in hypertensive patients. False-negative results in the dexamethasone suppression test (DST) in patients being treated with indomethacin have been reported. Thus, results of the DST should be interpreted with caution in these patients.