Mecillinam Chemical formula
Synonyms: Amdinocillin (USAN); FL-1060; Mecilinam; Mécillinam; Mecillinamum; Mesillinaami; Ro-10-9070. (6R)-6-(Perhydroazepin-1-ylmethyleneamino)penicillanic acid.
Cyrillic synonym: Мециллинам.

💊 Chemical information

Chemical formula: C15H23N3O3S = 325.4.
CAS — 32887-01-7.
ATC — J01CA11.
ATC Vet — QJ01C A11.

💊 Adverse Effects and Precautions

As for Benzylpenicillin.


Mecillinam has been associated with acute attacks of porphyria and is considered unsafe in porphyric patients.

💊 Interactions

💊 Antimicrobial Action

Mecillinam is a derivative of amidinopenicillanic acid. Unlike benzylpenicillin and related antibiotics, it is active against many Gram-negative bacteria, in particular Enterobacteriaceae including Escherichia coli, Enterobacter, Klebsiella, Salmonella, and Shigella spp. The susceptibility of Proteus spp. varies; Serratia marcescens is generally resistant. It is less active against Neisseria spp. and Haemophilus influenzae. Pseudomonas aeruginosa and Bacteroides spp. are considered to be resistant. It is much less active against Gram-positive bacteria; enterococci including Enterococcus faecalis are resistant. Mecillinam interferes with the synthesis of the bacterial cell wall by binding with a different penicillin-binding protein from benzylpenicillin. This difference in mode of action may explain the synergism against many Gram-negative organisms that has been reported in vitro between mecillinam and various penicillins or cephalosporins. Mecillinam is inactivated by beta-lactamases, but is more stable than ampicillin.

💊 Pharmacokinetics

Mecillinam is poorly absorbed from the gastrointestinal tract. Peak plasma concentrations of about 6 and 12 micrograms/mL have been achieved half an hour after intramuscular doses of 200 and 400 mg, respectively. The usual plasma half-life of about 1 hour has been reported to be prolonged to 3 to 5 hours or more in severe renal impairment. Between 5 and 10% of mecillinam is bound to plasma proteins. Mecillinam is widely distributed into body tissues and fluids; little passes into the CSF unless the meninges are inflamed. It crosses the placenta into the fetal circulation; little appears to be distributed into breast milk. Mecillinam is metabolised to only a limited extent. From 50 to 70% of a parenteral dose may be excreted in the urine within 6 hours by glomerular filtration and tubular secretion. Renal tubular secretion can be reduced by probenecid. Some mecillinam is excreted in bile where high concentrations are achieved. Mecillinam is removed by haemodialysis.

💊 Uses and Administration

Mecillinam is a semisynthetic penicillin with a substituted amidino group at the 6-position of the penicillanic acid nucleus. It is given by slow intravenous injection, by intravenous infusion, or intramuscularly, in the treatment of susceptible Gram-negative infections (see under Antimicrobial Action, above). For urinary-tract infections a dose of 800 mg is given every 6 to 8 hours. A total dose of up to 60 mg/kg daily may be used in very severe infections. Mecillinam has been used with other beta lactams to extend the spectrum of antimicrobial activity to Gram-positive organisms and because of reported synergism against Gram-negative bacteria in vitro. The pivaloyloxymethyl ester of mecillinam, pivmecillinam, is used orally.

💊 Preparations

Proprietary Preparations

Denm.: Selexid; Gr.: Selexid; Norw.: Selexid; Swed.: Selexid.
Published April 23, 2019.