Methicillin

Drug Levels and Effects:




Summary of Use during Lactation:


Methicillin is acceptable to use during breastfeeding. Limited information indicates that maternal doses of methicillin up to 4 grams daily produce low levels in milk that are not expected to cause adverse effects in breastfed infants. Occasionally, disruption of the infant's gastrointestinal flora, resulting in diarrhea or thrush, has been reported with penicillins, but these effects have not been adequately evaluated.


Drug Levels:


Maternal Levels.

Intramuscular injections of methicillin 1 gram every 6 hours for 6 to 9 days in 17 women with monolateral mastitis yielded methicillin levels in milk that reached a peak of 0.31 mg/L 3 hours after the first dose on the first day in the healthy breast, and much lower levels in the breast with mastitis. After the last dose, peak milk levels of 1.53 mg/L occurred 6 hours after the dose. Methicillin milk levels from both breasts were equal.[1]

After a single intramuscular dose of 1 gram of methicillin in 3 women, milk levels ranged from 0.2 to 0.3 mg/L between 1 and 6 hours.[2]

Infant Levels.

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


Effects in Breastfed Infants:


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


Possible Effects on Lactation:


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


References:


1. Kulakov VI, Zak IR, Kulikova NN, Smekuna FA. [Body pharmacokinetics of methicillin, oxacillin and cephaloridine in puerperal mastitis]. Antibiotiki. 1981;26:110-3. PMID:7212690
2. Matsuda S. Transfer of antibiotics into maternal milk. Biol Res Pregnancy. 1984;5:57-60. PMID:6743732



Substance Identification:




Substance Name:

Methicillin

CAS Registry Number:

61-32-5

Drug Class:


  • Antiinfective Agents

  • Antibacterial Agents

  • Penicillins


  • Administrative Information:




    LactMed Record Number:


    176


    Last Revision Date:


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