Cloxacillin Sodium

Synonyms: BRL-1621; Cloxacilina sódica; Cloxacilline sodique; Cloxacillinum natricum; Cloxacillinum Natricum Monohydricum; Kloksacilino natrio druska; Kloksacylina sodowa; Kloksasilliininatrium; Kloxacilin sodná sůl monohydrát; Kloxacillinnatrium; Kloxacillin-nátrium; Natrii Cloxacillinum; P-25.
Cyrillic synonym: Натрий Клоксациллин.

💊 Chemical information

Chemical formula: C19H17ClN3NaO5S,H2O = 475.9.
CAS — 642-78-4 (anhydrous cloxacillin sodium); 708144-9 (cloxacillin sodium monohydrate).
ATC — J0 1 CF02.
ATC Vet — QJ01CF02.


In Chin., Eur., Int., Jpn, US, and Viet.

Ph. Eur. 6.2

(Cloxacillin Sodium). Semi-synthetic product derived from a fermentation product. A white or almost white, hygroscopic, crystalline powder. Freely soluble in water and in methyl alcohol; soluble in alcohol. A 10% solution in water has a pH of 5.0 to 7.0. Store at a temperature not exceeding 25° in airtight containers.

USP 31

(Cloxacillin Sodium). A white, odourless, crystalline powder. Freely soluble in water; soluble in alcohol; slightly soluble in chloroform. pH of a 1% solution in water is between 4.5 and 7.5. Store in airtight containers at a temperature not exceeding 25°.


Cloxacillin sodium has been reported to be incompatible with aminoglycosides and a number of other antimicrobials.

💊 Adverse Effects and Precautions

As for Flucloxacillin.

Effects on the kidneys.

1. García-Ortiz R, et al. Cloxacillin-induced acute tubulo interstitial nephritis. Ann Pharmacother 1992; 26: 1241–2.

Effects on the liver.

1. Enat R, et al. Cholestatic jaundice caused by cloxacillin: macrophage inhibition factor test in preventing rechallenge with hepatotoxic drugs. BMJ 1980; 280: 982–3
2. Konikoff F, et al. Cloxacillin-induced cholestatic jaundice. Am J Gastroenterol 1986; 81: 1082–3
3. Goland S, et al. Severe cholestatic hepatitis following cloxacillin treatment. Postgrad Med J 1998; 74: 59–60.

Sodium content.

Each g of cloxacillin sodium contains about 2.1 mmol of sodium.

💊 Interactions

💊 Antimicrobial Action

💊 Pharmacokinetics

Cloxacillin is incompletely absorbed from the gastrointestinal tract, and absorption is reduced by the presence of food in the stomach. After an oral dose of 500 mg, a peak plasma concentration of 7 to 15 micrograms/mL is attained in fasting subjects in 1 to 2 hours. Absorption is more complete when given by intramuscular injection and peak plasma concentrations of about 15 micrograms/mL have been observed 30 minutes after a dose of 500 mg. Doubling the dose can double the plasma concentration. About 94% of cloxacillin in the circulation is bound to plasma proteins. Cloxacillin has been reported to have a plasma halflife of 0.5 to 1 hour. The half-life is prolonged in neonates. Cloxacillin crosses the placenta and is distributed into breast milk. There is little diffusion into the CSF except when the meninges are inflamed. Therapeutic concentrations can be achieved in pleural and synovial fluids and in bone. Cloxacillin is metabolised to a limited extent, and the unchanged drug and metabolites are excreted in the urine by glomerular filtration and renal tubular secretion. About 35% of an oral dose is excreted in the urine and up to 10% in the bile. Cloxacillin is not removed by haemodialysis. Plasma concentrations are enhanced by probenecid. Reduced concentrations in patients with cystic fibrosis have been attributed to both enhanced tubular secretion and enhanced nonrenal clearance of cloxacillin.

💊 Uses and Administration

Cloxacillin is an isoxazolyl penicillin used similarly to flucloxacillin in the treatment of infections due to staphylococci resistant to benzylpenicillin. Cloxacillin is given orally as the sodium salt and doses are expressed in terms of the equivalent amount of cloxacillin; 1.09 g of cloxacillin sodium is equivalent to about 1 g of cloxacillin. It should be given at least 30 minutes before meals as the presence of food in the stomach reduces absorption. Usual oral doses are 250 to 500 mg four times daily. Children up to 2 years may be given a quarter of the daily adult dose and those over 2 years half the daily adult dose, in divided doses every 6 hours. Cloxacillin sodium has also been given by intramuscular or slow intravenous injection or infusion. Other routes have included intra-articular or intrapleural injection, and inhalation. Cloxacillin may be used with other antibacterials, including ampicillin, to produce a wider spectrum of activity. Cloxacillin benzathine is used in veterinary medicine.

💊 Preparations

USP 31: Cloxacillin Sodium Capsules; Cloxacillin Sodium for Oral Solution.

Proprietary Preparations

Belg.: Penstaphon; Canad.: Apo-Cloxi; Novo-Cloxin; Nu-Cloxi; Chile: Cloxapen†; Fin.: Ekvacillin†; Staflocil; Fr.: Orbenine; Gr.: Anaclosil; Orbenin; Staphyclox; Hong Kong: Apo-Cloxi; Cloxil†; Cloxin; Lidoxin; Monoclox; Prostaphlin-A; India: Bioclox; Iclox†; Indon.: Meixam; Israel: Loxavit; Orbenil; Malaysia: Monoclox; Oxacil†; Proxin†; Neth.: Orbenin†; Norw.: Ekvacillin; Philipp.: Avastoph; Caxin; Ciclox; Cloxigen; Eloxil; Encloxil; Eraclox; Excelox; Jogen; Lewinex; Medix; Orbenin; Oxaclen; Pannox; Patriflex; Prostaphilin-A; Solaze; Vamcloxil; Pol.: Syntarpen; S.Afr.: Cloxin; Orbenin; Singapore: Axocillin†; Cloxacap†; Lidoxin; Monoclox†; Spain: Anaclosil; Orbenin; Swed.: Ekvacillin; Thai.: Cloxa; Cloxalin; Cloxam; Cloxanbin; Cloxapan†; Cloxasian; Cloxgen; Cloxil; Cloxillin†; Corbin; Greater-Gloxa; KCil; Lidoxin; Loxzalin; Meiclox; Orbenin; Serviclox†; Socloxin; Syntoclox; Theraclox; Vaclox. Multi-ingredient: Cz.: Ampiclox†; Hong Kong: Ampiclox†; APT-Ampicloxa; Pamedox; Roscilox; India: ABClox; Adilox; Amclo†; Ampilox; Ampilox-LB; Amplus; Ampoxin; Ampoxin-LB; Bicidal Plus; Campilox; Clax; Hipenox; Imox-Clo; Imox-Clo LB; Megaclox; Megaclox LB; Megapen; Novaclox; Novaclox LB; Suprimox; Symbiotik; Irl.: Ampiclox†; Ital.: Amplium; S.Afr.: Ampiclox; Apen; Cloxam; Megamox; Ranclosil†; Thai.: Ampiclox; Viccillin-S.
Published January 28, 2019.