Antacids Comb.Adverse Effect: Decreased methenamine effectivenessClinical Management: Concurrent administration of methenamine and antacids is not recommended. If concurrent use cannot be avoided, administer methenamine at least several hours before the antacid is taken. Because staggered administration may not be completely reliable, aggressively monitor these patients for continued antibiotic efficacy.
SulphamethizoleAdverse Effect: increased risk of crystalluriaClinical Management: Avoid concurrent administration of methenamine and sulfamethizole, since sulfamethizole may form an insoluble precipitate in acidic urine. If a sulfonamide must be used, sulfisoxazole, which is more soluble, would be an alternative. |