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Primsol (trimethoprim) Disease Interactions

There are 3 disease interactions with Primsol (trimethoprim):


Trimethoprim (Includes Primsol) ↔ Folate Deficiency

Severe Potential Hazard, High plausibility

Applies to: Anemia Associated with Folate Deficiency, Folic Acid/Cyanocobalamin Deficiency, Renal Dysfunction, Hemolytic Anemia, Alcoholism, Malnourished

The use of trimethoprim is contraindicated in patients with documented megaloblastic anemia due to folate deficiency. Trimethoprim inhibits dihydrofolate reductase, an enzyme necessary in the synthesis of tetrahydrofolic acid, or the metabolically active form of folic acid. Thrombocytopenia, neutropenia, megaloblastic anemia, and methemoglobinemia have been reported rarely. However, the risk is increased in the presence of folate deficiency, chronic hemolytic anemia and/or renal impairment, as well as during prolonged therapy (e.g., > 6 months) with high dosages. Therapy with trimethoprim should be administered cautiously under these conditions and in patients with suspected folate depletion (e.g., elderly, alcoholic, malnourished or debilitated patients). Folic acid supplementation, if necessary, may be administered concomitantly without interfering with the antibacterial action of trimethoprim. Patients should be instructed to immediately report any signs or symptoms suggestive of hematologic toxicity such as fever, sore throat, local infection, bleeding, pallor, dizziness, or jaundice. Leucovorin (folinic acid) should be administered if bone marrow depression is detected.


  1. "Product Information. Trimpex (trimethoprim)." Roche Laboratories, Nutley, NJ.
  2. Sheehan J "Trimethoprim-associated marrow toxicity." Lancet 2 (1981): 692
  3. Chan M, Beale D, Moorhead J "Acute megaloblastosis due to cotrimoxazole." Br J Clin Pract 34 (1980): 87-8
View all 4 references

Trimethoprim (Includes Primsol) ↔ Dialysis

Moderate Potential Hazard, High plausibility

Applies to: hemodialysis

Trimethoprim is moderately removed by hemodialysis. Doses should either be scheduled for administration after dialysis or supplemental doses be given after dialysis.


  1. "Product Information. Proloprim (trimethoprim)." Glaxo Wellcome, Research Triangle Park, NC.
  2. "Product Information. Trimpex (trimethoprim)." Roche Laboratories, Nutley, NJ.
  3. Nissenson AR, Wilson C, Holazo A "Pharmacokinetics of intravenous trimethoprim-sulfamethoxazole during hemodialysis." Am J Nephrol 7 (1987): 270-4
View all 4 references

Trimethoprim (Includes Primsol) ↔ Renal Dysfunction

Moderate Potential Hazard, High plausibility

Applies to: Renal Dysfunction

Trimethoprim is primarily eliminated by the kidney. The serum concentration of trimethoprim may be increased and the half-life prolonged in patients with impaired renal function. Dosage adjustments may be necessary and modifications should be based on the degree of renal impairment as well as severity of infection. The manufacturers recommend a dosage of 50 mg every 12 hours in patients with creatinine clearance between 15 to 30 mL/min and not using the drug in patients with creatinine clearance below 15 mL/min.


  1. Nolte H, Buttner H "Pharmacokinetics of trimethoprim and its combination with sulfamethoxazole in man after single and chronic oral administration." Chemotherapy 18 (1973): 274-84
  2. Watson ID, Stewart MJ, Wiles A, McIntosh SJ "Pharmacokinetics of two dosage levels of trimethoprim to "steady-state" in normal volunteers." J Int Med Res 11 (1983): 137-44
  3. Bergan T, Brodwall E, Vik-Mo H, Anstad U "Pharmacokinetics of sulphadiazine, sulphamethoxazole and trimethoprim in patients with varying renal function." Infection 7 (1979): s382-7
View all 11 references

Primsol (trimethoprim) drug Interactions

There are 175 drug interactions with Primsol (trimethoprim)

Primsol (trimethoprim) alcohol/food Interactions

There is 1 alcohol/food interaction with Primsol (trimethoprim)

Drug Interaction Classification

The classifications below are a general guideline only. It is difficult to determine the relevance of a particular drug interaction to any individual given the large number of variables.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No information available.

Do not stop taking any medications without consulting your healthcare provider.

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