An 85-year-old man developed higher than normal blood levels of potassium following several months of treatment with piroxicam.1 Until more is known, people taking piroxicam for long periods should have their blood checked regularly for high potassium levels and may need to avoid high potassium intake with the guidance of a health practitioner.
Piroxicam may prevent inflammation by blocking the activity of enzymes that depend on folic acid.2 However, other studies show that people taking NSAIDs such as aspirin have lower than normal levels of folic acid in their red blood cells.3 Further research is needed to determine whether supplemental folic acid prevents a deficiency of the vitamin or indirectly reduces the beneficial effects of piroxicam.
Willow bark contains salicin, which is related to aspirin. Both salicin and aspirin produce anti-inflammatory effects after they have been converted to salicylic acid in the body. Taking aspirin significantly lowers blood levels of piroxicam and increases the potential for adverse side effects.4 Though no studies have investigated interactions between willow bark and piroxicam, people taking the drug should avoid the herb until more information is available.
1. Miller KP, Lazar EJ, Fotino S. Severe hyperkalemia during piroxicam therapy. Arch Int Med 1984;144:2414–5.
2. Baggott JE, Morgan SL, Ha T, et al. Inhibition of folate-dependent enzymes by non-steroidal anti-inflammatory drugs. Biochem J 1992;282:197–202.
3. Alter HJ, Zvaifler NJ, Rath CE. Interrelationship of rheumatoid arthritis, folic acid, and aspirin. Blood 1971;38:405–16.
4. Sifton DW, ed. Physicians Desk Reference. Montvale, NJ: Medical Economics Company, Inc., 2000, 2342–4.
Last Review: 02-05-2013
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