Last update Oct. 13, 2022

Methicillin, Meticillin Sodium

Low Risk

Possibly safe. Probably compatible. Mild risk possible. Follow up recommended. Read the Comment.

It is a penicillinase-resistant penicillin that is no longer used clinically because of its renal side effects. It has been used in the treatment of staphylococcal infections resistant to benzylpenicillin. It is inactivated by gastric acid and must be given by injection.

It is excreted in breast milk in clinically insignificant amounts. (LactMed)

The possibility of transient gastroenteritis due to alteration of the intestinal flora in infants whose mothers take antibiotics should be taken into account. (Benyamini 2005)


Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

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Methicillin, Meticillin Sodium in other languages or writings:


Methicillin, Meticillin Sodium belongs to this group or family:


Variable Value Unit
Oral Bioavail. ≈ 0 %
Molecular weight 420 daltons
Protein Binding 40 %
pKa 2.96 -
Tmax 0.5 - 1 hours
0.5 - 2 hours
Theoretical Dose 0.03 - 0.23 mg/Kg/d


  1. LactMed. Drugs and Lactation Database (LactMed). Internet. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: 2006 - Consulted on April 16, 2024 Full text (link to original source)
  2. Benyamini L, Merlob P, Stahl B, Braunstein R, Bortnik O, Bulkowstein M, Zimmerman D, Berkovitch M. The safety of amoxicillin/clavulanic acid and cefuroxime during lactation. Ther Drug Monit. 2005 Abstract

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