Sulfamethoxazole And Trimethoprim

Marked but reversible nephrotoxicity reported with coadministration in renal transplant recipients.

Avoid concomitant use. Leucovorin decreases effectiveness of trimethoprim-sulfamethoxazole, associated with increased treatment failure and mortality in HIV patients with Pneumocystis jirovecii pneumonia.

Sulfonamides displace methotrexate from plasma protein binding and compete with renal transport, increasing free methotrexate concentrations.

Reports suggest megaloblastic anemia risk when pyrimethamine doses exceed 25 mg weekly with concurrent sulfamethoxazole and trimethoprim use.

Methotrexate Avoid concurrent use Sulfonamides can also displace methotrexate from plasma protein binding sites and can compete with the renal transport of methotrexate, thus increasing free methotrexate concentrations. Oral Hypoglycemics Monitor blood glucose more frequently Like other sulfonamide-containing drugs, BACTRIM potentiates the effect of oral hypoglycemic that are metabolized by CYP2C8 (e.g., pioglitazone, repaglinide, and rosiglitazone) or CYP2C9 (e.g., glipizide and glyburide) or eliminated renally via OCT2 (e.g., metformin).

Toxic delirium reported after concomitant intake of BACTRIM and amantadine, an OCT2 substrate.

In elderly patients concurrently receiving thiazide diuretics, an increased incidence of thrombocytopenia with purpura has been reported.

Three cases of hyperkalemia in elderly patients reported after concomitant intake of sulfamethoxazole and trimethoprim and ACE inhibitors.

Increased digoxin blood levels can occur with concomitant sulfamethoxazole and trimethoprim therapy, especially in elderly patients. Serum digoxin levels should be monitored.

Increased incidence of thrombocytopenia with purpura reported in elderly patients receiving certain diuretics, primarily thiazides.

Concomitant use with trimethoprim and drugs that induce hyperkalemia may cause hyperkalemia, particularly in patients with renal insufficiency or underlying potassium metabolism disorders.

Associated with myelosuppression or nephrotoxicity; coadministration should be considered only if potential benefits outweigh risks.

Increased sulfamethoxazole blood levels may occur in patients receiving indomethacin.

Concomitant use with levoleucovorin for acute treatment of Pneumocystis jiroveci pneumonia in HIV patients was associated with increased treatment failure and morbidity.

Concomitant use for acute treatment of Pneumocystis jiroveci pneumonia in HIV patients was associated with increased treatment failure and morbidity in placebo-controlled study.

Concomitant use for acute treatment of Pneumocystis jiroveci pneumonia in HIV-infected patients was associated with increased rates of treatment failure and morbidity.

Cases of interactions with memantine have been reported in the literature.

Enhanced myelosuppression noted when coadministered with mercaptopurine. Monitor CBC and adjust mercaptopurine dose for excessive myelosuppression.

BACTRIM inhibits hepatic metabolism of phenytoin, increasing phenytoin half-life by 39% and decreasing clearance by 27%.

Concomitant use with folinic acid associated with increased rates of treatment failure and mortality in acute Pneumocystis carinii pneumonia in HIV patients.

Sulfamethoxazole is an inhibitor of CYP2C9. Indomethacin Avoid concurrent use Increased sulfamethoxazole blood levels may occur in patients who are also receiving indomethacin.

Increased incidence of thrombocytopenia with purpura reported in elderly patients concurrently receiving thiazides.

Associated with myelosuppression or nephrotoxicity. Coadministration should be considered only if potential benefits outweigh risks.

Co-administration with valganciclovir should be considered only if potential benefits outweigh risks due to potential for higher toxicity from myelosuppression or nephrotoxicity.

BACTRIM may prolong prothrombin time in patients receiving warfarin. Sulfamethoxazole inhibits CYP2C9, increasing warfarin levels.

TMP/SMX increases systemic levels of dapsone and its metabolites (AUC increased ~40% for dapsone, ~20% for N-acetyldapsone, >100% for dapsone hydroxylamine). Monitor for increased dapsone exposure and potential toxicity.

TMP/SMX increases systemic levels of dapsone and its metabolites by approximately 40% for dapsone, 20% for N-acetyl-dapsone, and more than doubles dapsone hydroxylamine exposure.

May increase phenytoin serum levels; monitoring of phenytoin levels recommended.

Associated with myelosuppression or nephrotoxicity. Coadministration considered only if benefits outweigh risks.

BACTRIM potentiates oral hypoglycemic effects of glyburide. Additional blood glucose monitoring warranted.

BACTRIM potentiates oral hypoglycemic effects of glipizide. Additional blood glucose monitoring warranted.

Cases of interactions reported with metformin, an OCT2 substrate. Trimethoprim inhibits OCT2 transporter.

Interferes with enterohepatic recirculation, decreasing mycophenolate mofetil systemic exposure. Monitor for alterations in efficacy.

Interferes with enterohepatic recirculation, decreasing mycophenolic acid systemic exposure and potentially reducing Mycophenolate Mofetil efficacy. Monitor for alterations.

May increase phenytoin serum levels; monitoring of phenytoin levels recommended.

BACTRIM potentiates oral hypoglycemic effects of pioglitazone. Additional blood glucose monitoring warranted.

8,9 Procainamide Closely monitor for clinical and ECG signs of procainamide toxicity and/or procainamide plasma concentration if available Trimethoprim increases the plasma concentrations of procainamide and its active N-acetyl metabolite (NAPA) when trimethoprim and procainamide are coadministered. The increased procainamide and NAPA plasma concentrations that resulted from the pharmacokinetic interaction with trimethoprim are associated with further prolongation of the QTc interval.

BACTRIM potentiates oral hypoglycemic effects of repaglinide. Additional blood glucose monitoring warranted.

BACTRIM potentiates oral hypoglycemic effects of rosiglitazone. Additional blood glucose monitoring warranted.

Azithromycin had a modest effect on trimethoprim/sulfamethoxazole pharmacokinetics. No dosage adjustment recommended.

Used concomitantly in at least 50 patients with no interactions observed.

Used concomitantly with terazosin in at least 50 patients with no interactions observed.