Cloxacillin

Oral Antibiotics

Drug class: β-Lactam Antibiotics; Belongs to the class of beta-lactam antibiotics, specifically within the subgroup of penicillinase-resistant penicillins.

Cloxacillin (ORBENIN)（中文：氯唑西林）

Common Strengths

Common strengths of Cloxacillin include:

• 250 mg capsules
• 500 mg capsules
• 500 mg injectable powder for reconstitution

Drug Trade Names

Orbenin

Drug Usage

Cloxacillin is indicated for the treatment of:

• Impetigo
• Cellulitis
• Pneumonia
• Septic arthritis
• Osteomyelitis
• Infections caused by beta-lactamase producing Staphylococcus aureus (not effective against MRSA)

Mechanism of Action

Cloxacillin works by binding to specific penicillin-binding proteins (PBPs) in bacterial cell walls, inhibiting cell wall synthesis and leading to cell lysis. Its structure allows it to resist degradation by certain beta-lactamases produced by bacteria.

Route of Administration

Cloxacillin can be administered:

• Orally (capsules)
• Intravenously (IV) or intramuscularly (IM) as an injectable solution.

Dosages

Adults:

• 1 g every 6 hours for severe infections.

Renal Dosing:

• Adjustments are necessary for patients with renal impairment based on eGFR (estimated Glomerular Filtration Rate).The specific adjustments depend on the severity of renal dysfunction.

Side Effects

Frequency	Adverse reactions
Common Side Effects	Nausea
	Diarrhea
	Rash	Serious Side Effects	Allergic reactions (including anaphylaxis)
Clostridium difficile-associated diarrhea
Hematological disorders

Pharmacokinetics

• Elimination Half-Life: About 30 minutes to 1 hour.
• Onset of Action: Generally, within hours after administration.
• Duration of Action: Approximately 6 hours.

Drug Precautions

Pregnancy

It should only be used during pregnancy when the benefits outweigh the risks.

Breastfeeding

Cloxacillin is excreted in breast milk; consult a healthcare provider before use during breastfeeding.

Children and Elderly

Use with caution; dosing may vary based on age and weight in children. Elderly patients may be more sensitive to side effects.

Monitoring Items

• Signs of allergic reactions (e.g., rash, itching, swelling)
• Gastrointestinal symptoms (e.g., persistent diarrhea, abdominal pain)
• Liver and kidney function (especially in patients with pre-existing conditions)
• Blood counts for signs of hematological abnormalities if used for extended periods

Drug Interactions

• Fusidic Acid: May increase the risk of muscle toxicity.
• Methotrexate: Cloxacillin may reduce renal clearance of methotrexate, increasing its toxicity.
• Warfarin: Cloxacillin can enhance the anticoagulant effect of warfarin, require closer monitoring of INR levels.
• Tetracyclines: Concurrent use may reduce the effectiveness of tetracycline antibiotics.

FAQ

How Should I Take the Capsule?

Take cloxacillin on an empty stomach, ideally one hour before or two hours after meals for optimal absorption.

What Should I Avoid While Taking?

Avoid taking antidiarrheal medications without consulting a doctor if you experience diarrhea, as this may worsen symptoms. Also, avoid alcohol and other medications that may interact.

What Happens If I Miss a Dose?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose—do not double up.