OBJECT DRUGS

• Trimethoprim (Bactrim, Septra)

PRECIPITANT DRUGS

Potassium-sparing diuretics:

• Amiloride (Midamor)
• Eplerenone (Inspra)
• Spironolactone (Aldactone)
• Triamterene (Dyrenium)

Comment:

Trimethoprim alone often produces modest increases in serum potassium, and hyperkalemia can occur when it is combined with other drugs that increase potassium such as potassium-sparing diuretics. Hospitalizations for hyperkalemia are substantially higher in patients on spironolactone who take trimethoprim versus amoxicillin, for example. The risk may be increased in the presence of one or more predisposing factors such as significant renal impairment, severe diabetes, potassium supplements, high potassium diet, advanced age or additional drugs that can increase potassium such as drospirenone (Yasmin), heparins, nonselective beta-blockers, NSAIDs, COX-2 inhibitors, ACE inhibitors, angiotensin receptor blockers, cyclosporine, tacrolimus, succinylcholine, pentamidine, and potassium-containing salt substitutes.

Class 2: Use Only if Benefit Felt to Outweigh Risk

• Use Alternative: If possible use an antibiotic other than trimethoprim.
• Monitor: If trimethoprim is used in patients on potassium-sparing diuretics, monitor serum potassium concentrations, especially in patients with predisposing factors such as renal disease, diabetes, and advanced age.