Interactions between hiprex(methenamine) and Calcarb (calcium carbonate)
methenamine and calcium carbonate (Moderate Drug-Drug)
GENERALLY AVOID: Agents that produce an alkaline urine may decrease the antibacterial effectiveness of methenamine. Methenamine is most effective in an acidic milieu (pH less than 5.5) because acidic urine allows the formation of formaldehyde from methenamine. Large doses of antacids may also alkalinize the urine.
MANAGEMENT: This combination should be avoided, if possible. Frequent urine pH testing is recommended.
