Interaction between Sulfasalazine and Methenamine
Major
Others
| ID | DDInter1725 and DDInter1169 |
| Interaction | 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 | |
| Alternative for Sulfasalazine |
G01A
Tinidazole
Celecoxib
Brinzolamide (ophthalmic)
Sulfacetamide (ophthalmic)
Amphotericin B (cholesteryl sulfate)
More
|
| Alternative for Methenamine |
J01X
|
Potential Metabolism Interactions
Substrate-Substrate Interaction：If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction：Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction：Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.