Sulfamethoxazole-Trimethoprim (sulfamethoxazole/trimethoprim)

Dosage of co-trimoxazole is expressed in terms of the trimethoprim content of the fixed combination containing 5 mg of sulfamethoxazole to 1 mg of trimethoprim.

If trimethoprim is used for treatment of acute, uncomplicated urinary tract infections in adults with creatinine clearances of 15-30 mL/minute, dosage of the drug should be reduced to 50 mg every 12 hours. The drug is not recommended in patients with creatinine clearances less than 15 mL/minute.

For information on dosage of the fixed combination containing trimethoprim and sulfamethoxazole, see Co-trimoxazole 8:12.20.

In patients with impaired renal function, doses and/or frequency of administration of co-trimoxazole must be modified in response to the degree of renal impairment, severity of the infection, susceptibility of the causative organism, and serum concentrations of the drug. The manufacturers recommend that the usual adult daily dosage of co-trimoxazole be reduced 50% in patients with creatinine clearances of 15-30 mL/minute. Although the manufacturers recommend not using the drug in patients with creatinine clearances less than 15 mL/minute, some clinicians suggest using the drug in reduced dosages in these patients.

Trimethoprim is administered orally. Trimethoprim also is administered orally or IV as a fixed-combination preparation with sulfamethoxazole. (For information on the fixed combination containing trimethoprim and sulfamethoxazole, see Co-trimoxazole 8:12.20.)

No dosing information is available for this tab.

No dosing information is available for this tab.

There is no enhanced messaging for this drug.

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

There is no enhanced messaging for this drug.

There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

There are no moderate contraindications for this drug.

There is no enhanced messaging for this drug.

There are no severe adverse reactions for this drug.

There are no less severe adverse reactions for this drug.

No enhanced messaging available.

No enhanced messaging available.

Trimethoprim has been shown to be teratogenic in rats when given in doses 40 times the usual human dose; in rabbits, an overall increase in fetal loss was associated with trimethoprim doses 6 times the usual human dose. Although there are no adequate and controlled studies to date using trimethoprim in humans, a retrospective study that reported the outcome of 186 pregnancies suggested that the incidence of congenital abnormalities in those who received the fixed combination containing trimethoprim and sulfamethoxazole (co-trimoxazole) was similar to that in those who received a placebo. Because trimethoprim may interfere with folic acid metabolism, the drug should be used during pregnancy only when potential benefits justify possible risks to the fetus.

Trimethoprim and sulfamethoxazole, alone and in combination, have produced teratogenic effects, manifested principally as cleft palate, in some (but not all) studies in rats receiving dosages exceeding the usual human dosages. In addition, in some rabbit studies, an overall increase in fetal loss was associated with trimethoprim doses 6 times the usual human dose. Although there are no adequate and controlled studies to date in humans, studies in pregnant women suggest that the incidence of congenital abnormalities in those who received co-trimoxazole was similar to that in those who received a placebo; there were no abnormalities in 10 children whose mothers had received the drug during the first trimester. In one report, there were no congenital abnormalities in 35 children whose mothers had received co-trimoxazole at the time of conception or shortly thereafter. Because co-trimoxazole crosses the placenta and may interfere with folic acid metabolism, the drug should be used during pregnancy only when the potential benefits justify the possible risks to the fetus. Because sulfonamides may cause kernicterus in neonates, the manufacturers state that use of co-trimoxazole in pregnant women is contraindicated.

Trimethoprim is distributed into milk. Because trimethoprim may interfere with folic acid metabolism, the drug should be used with caution in nursing women.

Co-trimoxazole is distributed into milk. Because co-trimoxazole may interfere with folic acid metabolism, the drug should be used in nursing women only if the potential benefits justify the possible risks to the infant. Because sulfonamides may cause kernicterus in infants younger than 2 months of age, a decision should be made whether to discontinue nursing or co-trimoxazole or to use an alternative drug, taking into account the importance of co-trimoxazole to the woman.

No enhanced messaging available.