Title: Floxacillin
CAS Registry Number: 5250-39-5
CAS Name: (2S,5R,6R)-6-[[[3-(2-Chloro-6-fluorophenyl)-5-methyl-4-isoxazolyl]carbonyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Additional Names: 3-(2-chloro-6-fluorophenyl)-5-methyl-4-isoxazolylpenicillin; 6-[3-(2-chloro-6-fluorophenyl)-5-methyl-4-isoxazolecarboxamido]penicillanic acid; flucloxacillin
Manufacturers' Codes: BRL-2039
Molecular Formula: C19H17ClFN3O5S
Molecular Weight: 453.87
Percent Composition: C 50.28%, H 3.78%, Cl 7.81%, F 4.19%, N 9.26%, O 17.63%, S 7.06%
Literature References: Semi-synthetic antibiotic active against penicillin-resistant staphylococci. Halogen-substituted derivative of oxacillin, q.v. Prepn: ZA 6304323 (1964 to Beecham); Nayler, GB 978299; idem, US 3239507 (1964, 1966 both to Beecham). Pharmacology and toxicity: R. Sutherland et al., Br. Med. J. 4, 460 (1970). Clinical studies: Harding et al., Clin. Trials J. 7, 368 (1970); Qureshi et al., ibid. 375.
Derivative Type: Sodium monohydrate
CAS Registry Number: 34214-51-2
Trademarks: Abboflox (Abbott); Culpen (Fujisawa); Floxapen (GSK); Ladropen (Berk); Stafoxil (Yamanouchi); Staphlipen (Wyeth); Staphylex (GSK)
Molecular Formula: C19H16ClFN3NaO5S.H2O
Molecular Weight: 493.87
Percent Composition: C 46.21%, H 3.67%, Cl 7.18%, F 3.85%, N 8.51%, Na 4.66%, O 19.44%, S 6.49%
Properties: Freely sol in water. LD50 in mice (g/kg): 2.2 s.c., 3.8 orally (Sutherland).
Toxicity data: LD50 in mice (g/kg): 2.2 s.c., 3.8 orally (Sutherland)
Therap-Cat: Antibacterial.
Keywords: Antibacterial (Antibiotics); ?Lactams; Penicillins.
Floxuridine Fluacizine Fluanisone Fluazacort Fluazifop-butyl

Systematic (IUPAC) name
(2S,5R,6R)-6-({[3-(2-chloro-5-fluorophenyl)-5-methylisoxazole-4-yl]carbonyl}amino)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Clinical data
AHFS/Drugs.com Micromedex Detailed Consumer Information
Pregnancy cat. B1 (AU)
Legal status Prescription Only (S4) (AU) POM (UK)
Routes Oral, IM, IV, intrapleural, intraarticular
Pharmacokinetic data
Bioavailability 50–70%
Metabolism Hepatic
Half-life 0.75–1 hour
Excretion Renal
CAS number 5250-39-5 YesY
ATC code J01CF05 QJ51CF05
PubChem CID 21319
DrugBank DB00301
ChemSpider 20037 YesY
UNII 43B2M34G2V YesY
KEGG D04196 YesY
Chemical data
Formula C19H17ClFN3O5S 
Mol. mass 453.87 g/mol
 YesY (what is this?)  (verify)

Flucloxacillin (INN) or floxacillin (USAN) is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. Unlike other penicillins, flucloxacillin has activity against beta-lactamase-producing organisms such as Staphylococcus aureus[1] as it is beta-lactamase stable. However, it is ineffective against MRSA.[citation needed] It is very similar to dicloxacillin and these two agents are considered interchangeable. Flucloxacillin is available under a variety of trade names including Floxapen (Beecham, now GSK), Flopen (CSL), Staphylex (Alphapharm), and Softapen (Rephco Pharmaceuticals Limited), Flubex (Beximco Pharmaceuticals Ltd, Bangladesh).