Nifedipine NSAIDs

Drugs that can precipitate lactic acidosis in patients taking metformin include ACE inhibitors, thiazide diuretics, NSAIDs, and drugs such as furosemide, nifedipine, cimetidine, amiloride, triamterene, trimethoprim, and digoxin, which are all secreted in the renal tubules, compete with metformin, and can contribute to increased plasma metformin concentrations (76). 

A In this patient with well-documented CAD who is sip CABG, either terbutaline or nifedipine would be contraindicated. It is not entirely clear which would be the safest, but based on studies, the use of nifedipine in patients with documented CAD can lead to an increase in mortality. Of the other three, the next most dangerous medication is likely to be MgS04, which can lead to cardiopulmonary arrest at toxic levels. The safest choice between indo-methacin and the oxytocin antagonist is difficult to sort out. Indomethacin has a higher risk characterization at baseline than the oxytocin antagonist, and in a patient with CAD, there should be concerns about renal function which is an issue with NSAIDs. 

The interaction between indometacin and ACE inhibitors is well established, with several studies showing that indometacin can reduce the blood pressure-lowering effect ofa number of ACE inhibitors. The interaction may not occur in all patients. If indometacin is required in a patient taking any ACE inhibitor, it would be prudent to monitor blood pressure. In a few small comparative studies, indometacin has been shown to have less effect on the calcium-channel blockers amlodipine, felodipine, and nifedipine, than on enalapril. See also, Calcium-channel blockers -i-Aspirin or NSAIDs , p.861. Therefore, a calcium-channel blocker may sometimes be an alternative to an ACE inhibitor in a patient requiring indometacin. 

There is evidence that most NSAIDs can increase blood pressure in patients treated with antihypertensives, although some studies have not found the increase to be clinically relevant. In various small studies, indometacin appeared not to reduce the hypotensive effects of amlodipine, felodipine, nicardipine, nimodipine or verapamil, but it did in one of two studies with nifedipine, and one study with nitrendipine. Similarly, ibuprofen caused a small reduction in the antihypertensive effects of amlodipine. Diclofenac and sulindac appear not to interact with nifedipine, nor ibuprofen, naproxen, piroxicam or sulindac with verapamil, nor naproxen with nicardipine. Low-dose aspirin did not alter the antihypertensive effect of felodipine or nifedipine in one study, and long-term aspirin did not alter the cardiovascular benefits of nitrendipine in another. Diclofenac reduces verapamil serum levels and raises those of isradipine, but these changes are probably unimportant. 

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