Last update Feb. 5, 2024

C21H33N3O5S ; C15H23N3O3S


Safe substance and/or breastfeeding is the best option.

Pivmecilinam or Amdinofilin pivoxil (USA) is a prodrug of the beta-lactam antibiotic mecilinam (amdinofilin). Pivmecillinam is well absorbed from the gastrointestinal tract and is rapidly hydrolysed to the active drug mecillinam. It is indicated for the treatment of urinary tract infections. Oral administration 2 to 4 times daily.

Pivmecilinam(mecilinam has not been found in breast milk (Seiga 1977) or in such a trace amount that no effects on breastfed infants/newborns are anticipated. (Karo 223, AEMPS 2023, Knight 2019)

The manufacturer considers it compatible with breastfeeding. (Karo 223, AEMPS 2023, Knight 2019)

The oral bioavailability of mecilinam is very low, so it is administered in the form of pivmecilinam (which is well absorbed) and immediately converted to mecilinam by enzymatic hydrolysis (Roholt 1975). The little mecilinam that may pass into breast milk will not be absorbed by the infant.


We do not have alternatives for C21H33N3O5S ; C15H23N3O3S since it is relatively safe.

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.


C21H33N3O5S ; C15H23N3O3S belongs to this group or family:


Main tradenames from several countries containing C21H33N3O5S ; C15H23N3O3S in its composition:


Variable Value Unit
Oral Bioavail. Pivmec: 45-70; Mecilinam: ≈ 0 %
Molecular weight Pivmec: 440; Mec: 325 daltons
Protein Binding 5 - 10 %
VD 0.2 l/Kg
Tmax 1 - 1.5 hours
1 hours


  1. Karo Pharma. Pivmecillinam Package leaflet: Information for the user. 2023 Consulted on Feb. 5, 2024 Full text (in our servers)
  2. AEMPS (Karo Ph).. Pivmecilinam (Selexid). Ficha técnica. 2023 Full text (in our servers)
  3. Knight. Pivmecillinam (Selexide). Drug Summary. 2019 Full text (in our servers)
  4. Neu HC, Srinivasan S, Francke EL, Ortiz-Neu C, Christenson JG. Pharmacokinetics of amdinocillin and pivamdinocillin in normal volunteers. Am J Med. 1983 Aug 29;75(2A):60-4. Abstract
  5. Gambertoglio JG, Barriere SL, Lin ET, Conte JE Jr. Pharmacokinetics of mecillinam in health subjects. Antimicrob Agents Chemother. 1980 Dec;18(6):952-6. Abstract Full text (link to original source)
  6. Seiga K, Minagawa M, Yamaji K. Studies on pivmecillinam. Chemotherapy (Tokyo). 1977;25:347–51 Studies on pivmecillinam. Chemotherapy (Tokyo). 1977;25:347–51 Full text (link to original source) Full text (in our servers)
  7. Roholt K, Nielsen B, Kristensen. Pharmacokinetic studies with mecillinam and pivmecillinam. Chemotherapy. 1975;21(3-4):146-66. Abstract

Total visits


Help us improve this entry

How to cite this entry

Do you need more information or did not found what you were looking for?

   Write us at

e-lactancia is a resource recommended by El Parto Es Nuestro of Spain

Would you like to recommend the use of e-lactancia? Write to us at corporate mail of APILAM