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Systematic (IUPAC) name
1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Clinical data
AHFS/Drugs.com monograph
MedlinePlus a685017
  • AU: B2
  • US: B (No risk in non-human studies)
Legal status
Routes of
Pharmacokinetic data
Bioavailability 60 to 80%
Protein binding 98%
Metabolism Hepatic
Biological half-life 0.7 hours
Excretion Renal and biliary
CAS Registry Number 3116-76-5 YesY
ATC code J01CF01 QJ51CF01
PubChem CID: 18381
DrugBank DB00485 YesY
ChemSpider 17358 YesY
KEGG D02348 YesY
Chemical data
Formula C19H17Cl2N3O5S
Molecular mass 470.327 g/mol
 YesY (what is this?)  (verify)

Dicloxacillin (INN) is a narrow-spectrum β-Lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. It is active against beta-lactamase-producing organisms such as Staphylococcus aureus,[1] which would otherwise be resistant to most penicillins. It is very similar to flucloxacillin and these two agents are considered interchangeable. Dicloxacillin is available under a variety of trade names including Diclocil (BMS).

Mode of action[edit]

Main article: β-Lactam antibiotic

Like other β-Lactam antibiotics, dicloxacillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria.

Medicinal chemistry[edit]

Dicloxacillin is insensitive to beta-lactamase (also known as penicillinase) enzymes secreted by many penicillin-resistant bacteria. The presence of the isoxazolyl group on the side chain of the penicillin nucleus facilitates the β-lactamase resistance, since they are relatively intolerant of side-chain steric hindrance. Thus, it is able to bind to penicillin-binding proteins (PBPs) and inhibit peptidoglycan crosslinking, but is not bound by or inactivated by β-lactamases.

Clinical use[edit]

Dicloxacillin is more acid-stable than many other penicillins and can be given orally, in addition to parenteral routes. However, like methicillin, it is less potent than benzylpenicillin against non-β-lactamase-producing Gram-positive bacteria.

Dicloxacillin has similar pharmacokinetics, antibacterial activity, and indications to flucloxacillin, and the two agents are considered interchangeable. It is believed to have lower incidence of severe hepatic adverse effects than flucloxacillin, but a higher incidence of renal adverse effects.[2]

Available forms[edit]

Dicloxacillin is commercially available as the sodium salt dicloxacillin sodium in capsules (250- or 500-mg) and injections (powder for reconstitution, 500 and 1000 mg per vial). its also available as name of novaclox.


Dicloxacillin is indicated for the treatment of infections caused by susceptible bacteria. Specific approved indications include:[2]


Dicloxacillin is contraindicated in those with a previous history of allergy to penicillins, cephalosporins or carbapenems. It should also not be used in the eye, or those with a history of cholestatic hepatitis associated with the use of dicloxacillin or flucloxacillin.

It should be used with caution in the elderly; renal impairment does not need dose adjustment<Bennett WM, Aronoff GR, Golper TA et al: Drug Prescribing in Renal Failure. American College of Physicians, 3rd ed, Philadelphia, PA, 1994.> while those with hepatic impairment do, due to the risk of cholestatic hepatitis.[2]

Adverse effects[edit]

Common adverse drug reactions (ADRs) associated with the use of dicloxacillin include: diarrhoea, nausea, rash, urticaria, pain and inflammation at injection site, superinfection (including candidiasis), allergy, and transient increases in liver enzymes and bilirubin.[2]

On rare occasions, cholestatic jaundice (also referred to as cholestatic hepatitis) has been associated with dicloxacillin therapy. The reaction may occur up to several weeks after treatment has stopped, and takes weeks to resolve. The estimated incidence is 1 in 15,000 exposures, and is more frequent in people >55 years, females, and those with treatment longer than 2 weeks.[2]


Despite dicloxacillin's being insensitive to beta-lactamases, some organisms have developed resistance to it and other narrow-spectrum β-lactam antibiotics including methicillin. Such organisms include methicillin-resistant Staphylococcus aureus (MRSA).

See also[edit]


  1. ^ Miranda-Novales G, Leaños-Miranda BE, Vilchis-Pérez M, Solórzano-Santos F (2006). "In vitro activity effects of combinations of cephalothin, dicloxacillin, imipenem, vancomycin and amikacin against methicillin-resistant Staphylococcus spp. strains". Ann. Clin. Microbiol. Antimicrob. 5: 25. doi:10.1186/1476-0711-5-25. PMC 1617116. PMID 17034644. 
  2. ^ a b c d e Rossi S, editor. Australian Medicines Handbook 2006. Adelaide: Australian Medicines Handbook; 2006