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Drug Interactions between pyrimethamine / sulfadoxine and Uro-Phosphate

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Major

methenamine sulfadoxine

Applies to: Uro-Phosphate (methenamine / sodium biphosphate) and pyrimethamine / sulfadoxine

CONTRAINDICATED: Some sulfonamides can form an insoluble precipitate with formaldehyde, which is generated from the hydrolysis of methenamine in acidic urine maintained by the presence of hippuric acid.

MANAGEMENT: Methenamine preparations should not be given to patients taking sulfonamides due to the risk of crystalluria. An alkalinizing agent should not be added because this may render methenamine less effective.

References

  1. (2001) "Product Information. Urised (methenamine)." Polymedica Pharmaceuticals USA Inc
  2. (2002) "Product Information. Hiprex (methenamine)." Hoechst Marion Roussel

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Moderate

pyrimethamine sulfadoxine

Applies to: pyrimethamine / sulfadoxine and pyrimethamine / sulfadoxine

MONITOR: Coadministration of pyrimethamine in doses exceeding 25 mg per week with trimethoprim or sulfonamides may increase the risk of megaloblastic anemia and pancytopenia. The proposed mechanism is additive antifolate effects.

MANAGEMENT: Periodic clinical and laboratory monitoring for signs of folic acid deficiency and hematologic changes is advisable.

References

  1. "Multum Information Services, Inc. Expert Review Panel"
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."

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Drug and food interactions

Moderate

sodium biphosphate food

Applies to: Uro-Phosphate (methenamine / sodium biphosphate)

ADJUST DOSING INTERVAL: Bowel cleansing products can increase the gastrointestinal transit rate. Oral medications administered within one hour of the start of administration of the bowel cleansing solution may be flushed from the gastrointestinal tract and not properly absorbed.

MANAGEMENT: Patients should be advised that absorption of oral medications may be impaired during bowel cleansing treatment. Oral medications (e.g., anticonvulsants, oral contraceptives, antidiabetic agents, antibiotics) should not be administered during and within one hour of starting bowel cleansing treatment whenever possible. However, if concomitant use cannot be avoided, monitoring for reduced therapeutic effects may be advisable.

References

  1. "Product Information. Golytely (polyethylene glycol 3350 with electrolytes)." Braintree
  2. (2022) "Product Information. Prepopik (citric acid/Mg oxide/Na picosulfate)." Ferring Pharmaceuticals Inc

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
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 interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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