Systematic (IUPAC) name
(2S,5R,6R)-6-[(azepan-1-ylmethylene)amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Clinical data
Pregnancy cat.
  • US: B

  • Appears safe in pregnancy[1]
Legal status
  • Prescription only
Routes Intravenous, intramuscular
Pharmacokinetic data
Bioavailability Negligible
Protein binding 5 to 10%
Metabolism Some hepatic metabolism
Half-life 1 to 3 hours
Excretion Renal and biliary, mostly unchanged
CAS number  YesY
ATC code J01
ChemSpider  N
Chemical data
Formula C15H23N3O3S 
Mol. mass 325.426 g/mol

Mecillinam (INN) or amdinocillin (USAN), trade name Coactin, is an extended-spectrum penicillin antibiotic 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. Neither drug is available in the United States.[5]


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.[6][7]


Mecillinam is active against most pathogenic Gram-negative bacteria, except Pseudomonas aeruginosa and some species of Proteus.[5] 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).[8] Another large study conducted in Europe and Brazil obtained similar results — 95.9% of E. coli strains, for instance, were sensitive to mecillinam.[9]

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]


Mecillinam synthesis:[10]

For an alternative synthesis, see:[11]


  1. ^ a b c Nicolle LE (August 2000). = long&pmid = 10969050 "Pivmecillinam in the treatment of urinary tract infections". J Antimicrob Chemother 46 (Suppl A): 35–39.  
  2. ^ a b Neu HC (1985). "Amdinocillin: a novel penicillin. Antibacterial activity, pharmacology and clinical use". Pharmacotherapy 5 (1): 1–10.  
  3. ^ Clarke PD, Geddes AM, McGhie D, Wall JC (July 1976). "Mecillinam: a new antibiotic for enteric fever".  
  4. ^ Geddes AM, Clarke PD (July 1977). "The treatment of enteric fever with mecillinam". J Antimicrob Chemother. 3 Suppl B: 101–2.  
  5. ^ a b Pham P, Bartlett JG (August 28, 2008). "Amdinocillin (Mecillinam)". Point-of-Care Information Technology ABX Guide.   Retrieved on August 31, 2008. Freely available with registration.
  6. ^ Lund F, Tybring L (April 1972). "6β-amidinopenicillanic acids—a new group of antibiotics". Nature New Biol 236 (66): 135–7.  
  7. ^ Tybring L, Melchior NH (September 1975). "Mecillinam (FL 1060), a 6β-Amidinopenicillanic Acid Derivative: Bactericidal Action and Synergy In Vitro".  
  8. ^ 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.  
  9. ^ 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.  
  10. ^ Sakamoto, F.; Ikeda, S.; Hirayama, R.; Moriyama, M.; Sotomura, M.; Tsukamoto, G. (1987). "Studies on prodrugs. VI Preparation and characterization of (5-substituted 2-oxo-1,3-dioxol-4-yl)methyl esters of mecillinam". Chemical & Pharmaceutical Bulletin 35 (2): 642.  
  11. ^ Lund, F.; Tybring, L. (1972). "6β-Amidinopenicillanic Acids—a New Group of Antibiotics". Nature New Biology 236 (66): 135.  

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