Mefenamic Acid

Even in patients without prior exposure anaphylactoid reactions may occur; patients with "aspirin triad" (bronchial asthma, aspirin intolerance, rhinitis) may be at increased risk. Contraindicated in patients who experience bronchospasm, asthma, rhinitis, or urticaria with NSAID or aspirin therapy.

NSAIDs cause an increased risk of serious (and potentially fatal) adverse cardiovascular thrombotic events, including MI and stroke. Risk may occur early during treatment and may increase with duration of use. Relative risk appears to be similar in those with and without known cardiovascular disease or risk factors for cardiovascular disease; however, absolute incidence of serious cardiovascular thrombotic events (which may occur early during treatment) was higher in patients with known cardiovascular disease or risk factors and in those receiving higher doses. New onset hypertension or exacerbation of hypertension may occur (NSAIDs may also impair response to ACE inhibitors, thiazide diuretics, or loop diuretics); may contribute to cardiovascular events; monitor blood pressure; use with caution in patients with hypertension. May cause sodium and fluid retention; use with caution in patients with edema. Avoid use in heart failure (ACCF/AHA [Yancy, 2013]). Avoid use in patients with recent MI unless benefits outweigh risk of cardiovascular thrombotic events. Use the lowest effective dose for the shortest duration of time, consistent with individual patient goals, to reduce risk of cardiovascular events; alternate therapies should be considered for patients at high risk.

May cause drowsiness, dizziness, blurred vision, and other neurologic effects which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).

NSAIDs cause increased risk of serious GI inflammation, ulceration, bleeding, and perforation (may be fatal); elderly patients and patients with history of peptic ulcer disease and/or GI bleeding are at greater risk for serious GI events. These events may occur at any time during therapy and without warning. Avoid use in patients with active GI bleeding. In patients with a history of acute lower GI bleeding, avoid use of non-aspirin NSAIDs, especially if due to angioectasia or diverticulosis (Strate 2016). Use caution with a history of GI ulcers, concurrent therapy known to increase the risk of GI bleeding (eg, aspirin, anticoagulants and/or corticosteroids, selective serotonin reuptake inhibitors), advanced hepatic disease, coagulopathy, smoking, use of alcohol, or in the elderly or debilitated patients. Use the lowest effective dose for the shortest duration of time, consistent with individual patient goals, to reduce risk of GI adverse events; alternate therapies should be considered for patients at high risk. When used concomitantly with aspirin, a substantial increase in the risk of GI complications (eg, ulcer) occurs; concomitant gastroprotective therapy (eg, proton pump inhibitors) is recommended (Bhatt, 2008).

Platelet adhesion and aggregation may be decreased; may prolong bleeding time; patients with coagulation disorders or who are receiving anticoagulants should be monitored closely. Anemia may occur; patients on long-term NSAID therapy should be monitored for anemia. Rarely, NSAID use has been associated with potentially severe blood dyscrasias (eg, agranulocytosis, thrombocytopenia, aplastic anemia).

Transaminase elevations have been reported with use; closely monitor patients with any abnormal LFT. Rare (sometimes fatal) severe hepatic reactions (eg, fulminant hepatitis, hepatic necrosis, hepatic failure) have occurred with NSAID use; discontinue immediately if clinical signs or symptoms of hepatic disease develop or if systemic manifestations occur.

NSAID use may increase the risk of hyperkalemia, particularly in the elderly, diabetics, renal disease, and with concomitant use of other agents capable of inducing hyperkalemia (eg, ACE-inhibitors). Monitor potassium closely.

NSAID use may compromise existing renal function; dose-dependent decreases in prostaglandin synthesis may result from NSAID use, reducing renal blood flow which may cause renal decompensation (usually reversible). Patients with impaired renal function, dehydration, hypovolemia, heart failure, hepatic impairment, those taking diuretics, ACE inhibitors, and the elderly are at greater risk of renal toxicity. Rehydrate patient before starting therapy; monitor renal function closely. Long-term NSAID use may result in renal papillary necrosis and other renal injury.

NSAIDs may cause potentially fatal skin adverse events including exfoliative dermatitis, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN); may occur without warning; discontinue use at first appearance of skin rash (or any other sign of hypersensitivity). Disease-related concerns:

Contraindicated in patients with aspirin-sensitive asthma; severe and potentially fatal bronchospasm may occur. Use caution in patients with other forms of asthma.

Use is contraindicated in the setting of coronary artery bypass graft (CABG) surgery. Risk of MI and stroke may be increased with use following CABG surgery.

Use with caution in patients with hepatic impairment; dosage adjustments may be necessary due to extensive hepatic metabolism. Patients with advanced hepatic disease are at an increased risk of GI bleeding with NSAIDs.

Avoid use in patients with preexisting renal disease and in patients with advanced renal disease; monitor renal function closely if therapy must be initiated. Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Other warnings/precautions:

Withhold for at least 4 to 6 half-lives prior to surgical or dental procedures.