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Clinical data
Trade namesCoactin, Leo, Selexid, Selexidin
AHFS/Drugs.comInternational Drug Names
  • Appears safe in pregnancy[1]
Routes of
Intravenous, intramuscular
ATC code
Legal status
Legal status
  • AU: S4 (Prescription only)
  • UK: POM (Prescription only)
  • In general: ℞ (Prescription only)
Pharmacokinetic data
Protein binding5 to 10%
MetabolismSome hepatic metabolism
Elimination half-life1 to 3 hours
ExcretionRenal and biliary, mostly unchanged
  • (2S,5R,6R)-6-[(E/Z)-(Azepan-1-ylmethylene)amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.046.601 Edit this at Wikidata
Chemical and physical data
Molar mass325.43 g·mol−1
3D model (JSmol)
  • CC1([C@@H](N2[C@H](S1)[C@@H](C2=O)N=CN3CCCCCC3)C(=O)O)C
 ☒NcheckY (what is this?)  (verify)

Mecillinam (INN) or amdinocillin (USAN) is an extended-spectrum penicillin antibiotic of the amidinopenicillin class that binds specifically to penicillin binding protein 2 (PBP2),[2] and is only considered to be active against Gram-negative bacteria. It is used primarily in the treatment of urinary tract infections, and has also been used to treat typhoid and paratyphoid fever.[3][4] Because mecillinam has very low oral bioavailability, an orally active prodrug was developed: pivmecillinam.

Medical uses

Mecillinam is used in the treatment of infections due to susceptible gram-negative bacteria, especially urinary tract infections which are most commonly caused by Escherichia coli.[5] Mecillinam is active against most pathogenic Gram-negative bacteria, except Pseudomonas aeruginosa and some species of Proteus.[6] Several studies have also found it to be as effective as other antibiotics for treating Staphylococcus saprophyticus infection, though it is Gram-positive, possibly because mecillinam reaches very high concentrations in urine.[1]

Worldwide resistance to mecillinam in bacteria causing urinary tract infection has remained very low since its introduction; a 2003 study conducted in 16 European countries and Canada found resistance to range from 1.2% (Escherichia coli) to 5.2% (Proteus mirabilis).[7] Another large study conducted in Europe and Brazil obtained similar results — 95.9% of E. coli strains, for instance, were sensitive to mecillinam.[8]

Adverse effects

The adverse effect profile of mecillinam is similar to that of other penicillins.[2] Its most common side effects are rash and gastrointestinal upset, including nausea and vomiting.[1]


With the codename FL 1060, mecillinam was developed by the Danish pharmaceutical company Leo Pharmaceutical Products (now LEO Pharma). It was first described in the scientific literature in a 1972 paper.[9][10]


  1. ^ a b c Nicolle LE (August 2000). "Pivmecillinam in the treatment of urinary tract infections". J Antimicrob Chemother. 46 (Suppl A): 35–39. doi:10.1093/jac/46.suppl_1.35. PMID 10969050.
  2. ^ a b Neu HC (1985). "Amdinocillin: a novel penicillin. Antibacterial activity, pharmacology and clinical use". Pharmacotherapy. 5 (1): 1–10. doi:10.1002/j.1875-9114.1985.tb04448.x. PMID 3885172. S2CID 46561080.
  3. ^ Clarke PD, Geddes AM, McGhie D, Wall JC (July 1976). "Mecillinam: a new antibiotic for enteric fever". Br Med J. 2 (6026): 14–5. doi:10.1136/bmj.2.6026.14. PMC 1687648. PMID 820402.
  4. ^ Geddes AM, Clarke PD (July 1977). "The treatment of enteric fever with mecillinam". J Antimicrob Chemother. 3 Suppl B: 101–2. doi:10.1093/jac/3.suppl_b.101. PMID 408321.
  5. ^ Wagenlehner, FME; Schmiemann, G; Hoyme, U; Fünfstück, R; Hummers-Pradier, E; Kaase, M; Kniehl, E; Selbach, I; Sester, U; Vahlensieck, W; Watermann, D; Naber, KG (12 February 2011). "Nationale S3-Leitlinie "Unkomplizierte Harnwegsinfektionen"" [National S3 guideline on uncomplicated urinary tract infection: recommendations for treatment and management of uncomplicated community-acquired bacterial urinary tract infections in adult patients]. Der Urologe (in German). 50 (2): 153–169. doi:10.1007/s00120-011-2512-z. PMID 21312083.
  6. ^ Pham P, Bartlett JG (August 28, 2008). "Amdinocillin (Mecillinam)". Point-of-Care Information Technology ABX Guide. Johns Hopkins University. Archived from the original on February 4, 2009. Retrieved September 1, 2008. Retrieved on August 31, 2008. Freely available with registration.
  7. ^ Kahlmeter G (January 2003). "An international survey of the antimicrobial susceptibility of pathogens from uncomplicated urinary tract infections: the ECO·SENS Project". J Antimicrob Chemother. 51 (1): 69–76. doi:10.1093/jac/dkg028. PMID 12493789.
  8. ^ Naber KG, Schito G, Botto H, Palou J, Mazzei T (May 2008). "Surveillance Study in Europe and Brazil on Clinical Aspects and Antimicrobial Resistance Epidemiology in Females with Cystitis (ARESC): Implications for Empiric Therapy". Eur Urol. 54 (5): 1164–75. doi:10.1016/j.eururo.2008.05.010. PMID 18511178.
  9. ^ Lund F, Tybring L (April 1972). "6β-amidinopenicillanic acids—a new group of antibiotics". Nature New Biology. 236 (66): 135–7. doi:10.1038/236135c0. PMID 4402006. S2CID 4293996.
  10. ^ Tybring L, Melchior NH (September 1975). "Mecillinam (FL 1060), a 6β-Amidinopenicillanic Acid Derivative: Bactericidal Action and Synergy In Vitro". Antimicrob Agents Chemother. 8 (3): 271–6. doi:10.1128/aac.8.3.271. PMC 429305. PMID 170856.