For S, cloxacillin (0–2048 µg/mL; 20–24 h) exhibits satisfactory antibacterial action. MIC values for aureus 8325-4 and DU1090 are both 0.125 µg/mL[1]. In vitro, cloxacillin (0.015625 μg/mL; 6 h) suppresses the hemolytic activity of Hlα, and this suppression is enhanced when combined with TZ and TZ. Additionally, cloxacillin inhibits the inflammatory response by preventing the activation of MAPKs, NF-кB, and proteins linked to NLRP3[1].

Mice are protected against S by cloxacillin (1.6125 mg/kg; sc; 12-h intervals for 72 h). When combined with thioridazine and tetracycline, aureus can cause peritonitis in vivo[1]. When combined with anti-IL-15 antibodies, cloxacillin (7.5 mg/per; ip; twice daily starting on day 3) results in less severe synovitis and less bone erosion[3].

Cell Viability Assay[1]
Cell Types: S. aureus 8325-4, S. aureus DU1090 (an Hlα-deleted strain)
Tested Concentrations: 0-2048 µg/mL
Incubation Duration: 20-24 h
Experimental Results: Inhibited S. aureus 8325-4 and DU1090 with MIC values both of 0.125 μg/mL.

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Western Blot Analysis[1]
Cell Types: S. aureus 8325-4
Tested Concentrations: 0.015625 μg/mL (combines with Thioridazine (TZ, 0.25 μg/mL) and Tetracycline (TC, 0.03125 μg/mL)).
Incubation Duration: 6 h
Experimental Results: Inhibited the expression of Hlα and the inhibition was more pronounced when combined with TZ and TC.

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Western Blot Analysis[1]
Cell Types: RAW264.7 cells (exposes to S. aureus 8325-4/DU1090 or pure Hlα)
Tested Concentrations: 0.015625 μg/mL (combines with TZ (0.25 μg/mL) and TC (0.03125 μg/mL)).
Incubation Duration: 6 h
Experimental Results: Inhibited the activation of MAPKs, NF -кB and NLRP3-related proteins thereby inhibiting the inflammatory response when combined with TC and TZ.

Animal/Disease Models: Female balb/c (Bagg ALBino) mouse (6weeks old; peritonitis model)[1].
Doses: 1.6125 mg/kg (combines with TC (3.125 mg/kg) and TZ (25 mg/kg))
Route of Administration: subcutaneous (sc) injection; 12-h intervals for 72 h.
Experimental Results: decreased the degree of inflammatory cell infiltration in the mouse lung tissue and alveolar structures tended to be normal. Dramatically decreased the pathological changes in spleen and liver tissue, as well as diminished the CFU counts of S. aureus in the peritoneal cavity.

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Animal/Disease Models: Female wildtype C57BL/6 mice (8weeks old; systemic S. aureus-induced arthritis model)
Doses: 7.5 mg/per (combines with 25 µg/per anti-IL-15 antibodies)
Route of Administration: intraperitoneal (ip)injection; twice (two times) daily from day 3 (after bacterial inoculation) and stopped at day 6.
Experimental Results: demonstrated activities of reducing severe synovitis and bone erosions when combined with anti-IL-15 antibodies.

Absorption, Distribution and Excretion
Antimicrobial drugs are readily absorbed from the gastrointestinal tract. …Antimicrobial drugs are rapidly but incompletely absorbed from the gastrointestinal tract (30-80%). Absorption is more efficient when taken on an empty stomach. After oral administration of 1 gram of oxacillin, peak plasma concentrations are reached within 1 hour, approximately 5-10 micrograms/mL; cloxacillin reaches similar values. Due to incomplete absorption, plasma concentrations are higher after intramuscular injection, and more drug is recovered in the urine. …They bind very well to plasma albumin (approximately 90-95%); hemodialysis cannot significantly remove circulating drugs. Typically, after oral administration of a standard dose, about half of the drug is excreted in the urine within the first 6 hours. In addition, the drug is primarily excreted via the liver and bile. Isoxazolidinyl penicillins are rapidly excreted by the kidneys; concurrent administration of probenecid leads to higher plasma drug concentrations and a longer duration of action. /Penicillins/
For more complete data on the absorption, distribution, and excretion of cloxacillin (16 in total), please visit the HSDB records page.

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Metabolism/Metabolites
Like other penicillins, cloxacillin appears to be metabolized via β-lactam ring cleavage to produce inactive penicillic acid metabolites.
Penicillins can be slowly converted in vivo into intermediates, such as penicillic acid, which can react with the corresponding components in tissues. /Penicillins/
Cloxacillin is partially metabolized into active and inactive metabolites. In one study, following a single oral dose of 500 mg cloxacillin, 22% of the absorbed dose was hydrolyzed to penicillic acid, which is microbiologically inactive. Cloxacillin is also slightly hydroxylated to produce a microbiologically active metabolite, the activity of which appears to be comparable to that of cloxacillin.

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Biological Half-Life
Half-life…between 30 and 60 minutes. In children receiving treatment for staphylococcal infections, the mean elimination half-life was 71 minutes. In adults with normal renal function, the serum half-life of cloxacillin was 0.4–0.8 hours. In patients with impaired renal function, the serum half-life of cloxacillin was slightly prolonged; reportedly, the half-life in patients with severe renal impairment was 0.8–2.3 hours. In a study of children aged 1 week to 2 years, the serum elimination half-life of cloxacillin was 0.8–1.5 hours. Neonatal serum concentrations of cloxacillin are generally higher than in older children, and the serum half-life is also longer.

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Limited information suggests that cloxacillin concentrations in breast milk are low and are not expected to have adverse effects on breastfed infants. There are reports that penicillin-type drugs occasionally disrupt the infant's gut microbiota, leading to diarrhea or thrush, but these effects have not been fully assessed. Cloxacillin is safe for breastfeeding women.
◉ Effects on Breastfed Infants
In a telephone follow-up study, 10 breastfeeding mothers reported taking cloxacillin (dosage not specified). Two of these mothers reported their infants experiencing diarrhea. No rashes or candidiasis were reported in exposed infants.
◉ Effects on Lactation and Breast Milk
As of the revision date, no relevant published information was found.
Protein Binding

Cloxacillin has approximately 94% protein binding in plasma, primarily bound to albumin.

[1]. The combination of cloxacillin, thioridazine and tetracycline protects mice against Staphylococcus aureus peritonitis by inhibiting α-Hemolysin-induced MAPK/NF-κB/NLRP3 activation. Int J Biol Macromol. 2022 Feb 15;198:1-10.

[2]. Antibiotics with Interleukin-15 Inhibition Reduce Joint Inflammation and Bone Erosions but Not Cartilage Destruction in Staphylococcus aureus-Induced Arthritis. Infect Immun. 2018 Apr 23;86(5):e00960-17.

[3]. Group 1 beta-lactamases of Aeromonas caviae and their resistance to beta-lactam antibiotics. Can J Microbiol. 2003 Mar;49(3):207-15.

Cloxacillin is a semi-synthetic penicillin antibiotic with a 3-(2-chlorophenyl)-5-methylisoxazole-4-carboxamide group at position 6. It possesses antibacterial activity, is a semi-synthetic derivative, and is also a penicillin allergen and penicillin-like compound. It is functionally related to oxacillin and is the conjugate acid of cloxacillin (1-). Cloxacillin is a semi-synthetic penicillin antibiotic and a chlorinated derivative of oxacillin. Cloxacillin has been reported to exist in the Chinese honeybee (Apis cerana), and relevant data exist. Cloxacillin sodium is the sodium salt of cloxacillin, a semi-synthetic, β-lactamase-resistant penicillin antibiotic with antibacterial activity. Cloxacillin binds to and inactivates penicillin-binding protein (PBP) located on the inner membrane of the bacterial cell wall, thereby preventing the cross-linking of peptidoglycan, a key component of the bacterial cell wall. This leads to the destruction of the bacterial cell wall, ultimately resulting in bacterial cell lysis. Cloxacillin is a semi-synthetic β-lactamase-resistant penicillin antibiotic with antibacterial activity. Cloxacillin binds to and inactivates penicillin-binding proteins (PBPs) located on the inner membrane of bacterial cell walls, thereby preventing the cross-linking of peptidoglycans, a key component of the bacterial cell wall. This leads to the disruption of the bacterial cell wall, ultimately resulting in bacterial cell lysis. Cloxacillin is a semi-synthetic antibiotic and a chlorinated derivative of oxacillin. See also: Cloxacillin sodium (in salt form). Benzathine cloxacillin (in salt form). Drug Indications Cloxacillin is indicated for the treatment of infections caused by β-hemolytic streptococci, pneumococci, and staphylococci (including β-lactamase-producing bacteria). Mechanism of Action Cloxacillin inhibits the third (and final) stage of bacterial cell wall synthesis by binding to specific penicillin-binding proteins (PBPs) located within the bacterial cell wall. Subsequently, bacterial cell wall autolysins (such as autolysins) mediate cell lysis; cloxacillin may interfere with the action of autolysin inhibitors. ...Its antibacterial spectrum against Gram-positive bacteria is similar to that of penicillin, but its antibacterial spectrum is broader against penicillinase-producing strains or species. ...Its activity against non-penicillinase-producing bacteria, especially streptococci, is lower than that of penicillin G. /Cloxacillin monohydrate/ Because penicillin has no effect on existing cell walls, bacteria must be in a proliferative state for penicillin's antibacterial effect to manifest. Penicillin-like drugs Penicillin and its metabolites are potent immunogens because they can bind to proteins and act as haptens to trigger acute antibody-mediated immune responses. The most common (approximately 95%) or "major" determinant in penicillin allergy is the penicillin acyl determinant resulting from the ring-opening of the penicillin β-lactam ring. This allows penicillin to bind to proteins via the amide group. "Minor" determinants (less common) are other metabolites, including native penicillin and penicillinic acid. Penicillin drugs have bactericidal effects; they inhibit bacterial cell wall synthesis. Their action depends on penicillin's ability to reach and bind to penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. Penicillin-binding proteins (including transpeptidase, carboxypeptidase, and endopeptidase) are enzymes involved in the final stages of bacterial cell wall assembly and in the remodeling of the cell wall during growth and division. Penicillin binds to and inactivates these penicillin-binding proteins, leading to a weakened bacterial cell wall and eventual lysis. Tolerance develops with repeated administration of penicillin.

C19H18CLN3O5S

435.88

435.065

61-72-3

Cloxacillin sodium monohydrate;7081-44-9;Cloxacillin sodium;642-78-4

6098

Typically exists as solid at room temperature

1.6±0.1 g/cm3

689.7±55.0 °C at 760 mmHg

370.9±31.5 °C

0.0±2.3 mmHg at 25°C

1.685

2.53

2

7

4

29

722

3

ClC1=CC=CC=C1C1=NOC(C)=C1C(N[C@@H]1C(=O)N2[C@H](C(S[C@]12[H])(C)C)C(=O)O)=O

LQOLIRLGBULYKD-JKIFEVAISA-N

InChI=1S/C19H18ClN3O5S/c1-8-11(12(22-28-8)9-6-4-5-7-10(9)20)15(24)21-13-16(25)23-14(18(26)27)19(2,3)29-17(13)23/h4-7,13-14,17H,1-3H3,(H,21,24)(H,26,27)/t13-,14+,17-/m1/s1

4-Thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 6-(((3-(2-chlorophenyl)-5-methyl-4-isoxazolyl)carbonyl)amino)-3,3-dimethyl-7-oxo-, (2S-(2alpha,5alpha,6beta))-

HSDB-3042Cloxacillin HSDB3042 HSDB 3042

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)