Trimethoprim contraindications

Trimethoprim- sulfamethoxazole 8-10 mg/kg per day of trimethoprim component in 2 doses Nausea, vomiting, anorexia, rash, urticaria S Increasing pneumococcal resistance contraindicated in children under 2 months... 

Cephalexin is considered safe and effective. Nitrofurantoin should not be used after week 37 due to concern for hemolytic anemia in the newborn. Sulfa-containing drugs may increase risk for kernicterus in the newborn and should be avoided during the last weeks of gestation. Folate antagonists, such as trimethoprim, are relatively contraindicated during the first trimester because of their association with cardiovascular malformations. Fluoroquinolones and tetracyclines are contraindicated. 

The agent of choice depends on location. Trimethoprim-sulfamethoxazole is used for infections acquired in the United States. For infections acquired outside the United States, the agents of choice are ciprofloxacin, norfloxacin, and azithromycin. Fluoroquinolones are generally contraindicated in children and adolescents. 

Because both drugs may interfere with folic acid metabolism, their use during pregnancy is usually contraindicated by the potential for effects on the fetus, such as the development of neural tube defects associated with folate deficiency. The use of trimethoprim is contraindicated in patients with blood dyscrasias, hepatic damage, and renal impairment. 

Zidovudine should be used cautiously with any other agent that causes bone marrow suppression, such as interferon-a, trimethoprim-sulfamethoxazole, dap-sone, foscarnet, flucytosine, ganciclovir, and valganci-clovir. Probenecid and interferon-p inhibit the elimination of zidovudine therefore, a dosage reduction of zidovudine is necessary when the drugs are administered concurrently. Ribavirin inhibits the phosphorylation reactions that activate zidovudine, and zidovudine similarly inhibits the activation of stavudine thus, the coadministration of zidovudine with ribavirin or stavudine is contraindicated. 

Contraindications Hypersensitivity to trimethoprim or any sulfonamides, megaloblastic anemia due to folate deficiency. 

Sulfonamides are contraindicated in patients with known hypersensitivity or intolerance to any member of this drug femily. Sulfonamides are also contraindicated in pregnancy at term, for nursing mothers, and for infants less than 2 months old becanse they can promote kernicterus in the newborn by displacing bilirubin from plasma proteins. The sulfonamides, pyrimethamine, and trimethoprim are contraindicated in patients with documented blood dyscrasias. 

Suitability for patient. The use of the Pregaday suggests that the patient is pregnant and so the use of folate antagonists, like trimethoprim, is contraindicated. You will need to contact the prescriber with a suggested alternative. 

Dofetilide has weak affinity for CYP3A4. Concomitant use of dofetilide with cime-tidine, hydrochlorothiazide (including combination products), verapamil, trimethoprim, prochlorperazine, megestrol, or ketoconazole is contraindicated due to significant increases in dofetilide serum concentrations (see Table 8.3). 

The manufacturer of dofetilide notes that trimethoprim 160 mg (in combination with sulfamethoxazole 800 mg) twice daily given with dofetilide 500 micrograms twice daily for 4 days increased dofetilide peak levels by 93% and AUC by 103%. Trimethoprim inhibits the active renal tubular secretion mechanism by which dofetilide is eliminated, so reducing its loss from the body (see also Dofetilide + H2-receptor antagonists , p.255). There is a linear relationship between plasma dofetilide concentrations and prolongation of the QT interval, which increases the risk of torsade de pointes arrhythmia. For this reason, the manufacturer contraindicates the use of trimethoprim in patients on dofetilide. This would seem to be a prudent precaution. 

---