Mecillinam

Parenteral
Urinary tract infections

Hypersensitivity to penicillins; porphyria.

Renal impairment (particularly high doses). Avoid contact as skin sensitisation may occur. Monitor hepatic, renal and haematological status (high doses or prolonged use). Spirochete infections particularly syphilis. Suprainfection with penicillin-resistant organisms may occur with prolonged use. Avoid intrathecal route.

Hypersensitivity reactions including angioedema, urticaria, rash, serum sickness-like reactions, haemolytic anemia; nephropathy and interstitial nephritis; neutropenia, thrombocytopenia; CNS toxicity including convulsions; diarrhoea, nausea, antibiotic-associated colitis.
Potentially Fatal: Anaphylaxis.

Prolonged half-life with probenecid. Antagonism with bacteriostatic drugs e.g. chloramphenicol, tetracyclines. May prolong bleeding time when used with anticoagulants.

May interfere with diagnostic tests for urinary glucose using copper sulfate, direct Coombs' test and test for urinary or serum proteins. May interfere with diagnostic tests that use bacteria.

Description:
Mechanism of Action: Mecillinam, a semisynthetic penicillin, interferes with bacterial cell wall synthesis. It is active against gram-negative bacteria e.g. E. coli, Enterobacter, Klebsiella, Salmonella and Shigella spp. Susceptibility of Proteus spp varies. Serratia marcescens is resistant. It is less active against Neisseria spp and H. influenzae. P. aeruginosa and Bacteroides spp are resistant. It is much less active against gram-positive bacteria; enterococci including E. faecalis are resistant. It is inactivated by β-lactamases, but is more stable than ampicillin.
Pharmacokinetics:
Absorption: Poorly absorbed from the GI tract; peak plasma concentrations after 30 min (IM).
Distribution: Protein-binding: 5-10%. Widely distributed in body tissues and fluids; small amounts enter into the CSF; crosses the placenta and distributes into breast milk
Metabolism: Limited metabolism.
Excretion: Via urine (50-70% of parenteral dose) by glomerular filtration and tubular secretion; via bile. Plasma half-life: About 1 hr; ≥3-5 hr in severe renal impairment.

Penicillins