Methenamine

Drug Levels and Effects:




Summary of Use during Lactation:


Both the hippurate and mandelate salts of methenamine pass into milk in small quantities and appear acceptable to use, even while nursing a newborn.


Drug Levels:


Maternal Levels.

Six mothers nursing newborn infants were given methenamine hippurate 1 g orally. Five hours after the dose, a mean methenamine concentration of 7 mg/L was found in milk. In two other women, milk concentrations averaged 9.1 mg/L 2 to 3 hours after a 1 g dose of methenamine hippurate orally and 4.3 mg/L 6 to 7 hours after the dose. Based on the amount of milk ingested, the authors calculated the dose the infants received to be 0.05 to 0.1 mg/kg which is about 1% of the adult dose.[1]

Infant Levels.

Relevant published information was not found as of the revision date.


Effects in Breastfed Infants:


Four newborn infants were allowed to breastfeed in one study after a maternal dose of 1 gram of methenamine hippurate. No adverse effects were reported.[1]


Possible Effects on Lactation:


Relevant published information was not found as of the revision date.


Alternate Drugs to Consider:


Methenamine Hippurate,Methenamine Mandelate


References:


1. Allgen LG, Holmberg G, Persson B et al. Biological fate of methenamine in man. Acta Obstet Gynecol Scand. 1979;58:287-93. PMID:484222



Substance Identification:




Substance Name:

Methenamine

CAS Registry Number:

100-97-0

Drug Class:


  • Antiinfective Agents, Urinary

  • Antibacterial Agents


  • Administrative Information:




    LactMed Record Number:


    175


    Last Revision Date:


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