Cephalothin: Uses, Dosage, Side Effects & Interactions

Introduction

Cephalothin is a first-generation cephalosporin antibiotic used for the treatment of various bacterial infections. It is a semisynthetic, broad-spectrum antimicrobial agent with the chemical formula C16H16N2O6S2. Cephalothin works by inhibiting the synthesis of the bacterial cell wall, leading to cell lysis and death.

Medical Uses

Cephalothin is indicated for the treatment of infections caused by susceptible strains of bacteria, including Staphylococcus aureus, Streptococcus pyogenes, and other gram-positive and gram-negative organisms. It is commonly used to treat respiratory tract infections, urinary tract infections, skin and soft tissue infections, and infections of the bones and joints. Cephalothin is also used prophylactically in surgical procedures to prevent postoperative infections.

Dosage and Administration

Cephalothin is administered parenterally, either by intramuscular injection or intravenous infusion. The dosage depends on the severity of the infection, the patient’s age and weight, and renal function. Adults typically receive 1-2 grams every 4-6 hours, while children receive 50-100 mg/kg/day in divided doses. Dose adjustments may be necessary for patients with impaired renal function.

Side Effects and Safety

Common side effects of cephalothin include injection site reactions, gastrointestinal disturbances (nausea, vomiting, diarrhea), and hypersensitivity reactions (rash, urticaria, fever). Rare but serious adverse effects include anaphylaxis, pseudomembranous colitis, and hematologic abnormalities. Cephalothin is contraindicated in patients with known hypersensitivity to cephalosporins or penicillins.

Drug Interactions

Cephalothin may interact with other medications, including aminoglycosides, loop diuretics, and anticoagulants. Concomitant use of cephalothin with nephrotoxic drugs may increase the risk of renal dysfunction. The efficacy of cephalothin may be reduced by penicillinase-producing bacteria.

Mechanism of Action

Cephalothin exerts its antibacterial effect by interfering with the synthesis of the bacterial cell wall. It binds to and inhibits penicillin-binding proteins (PBPs), enzymes involved in the cross-linking of peptidoglycan, a crucial structural component of the cell wall. This disruption leads to cell lysis and bacterial death.

Antibiotic Resistance

Bacterial resistance to cephalothin can occur through various mechanisms, including the production of β-lactamases that inactivate the drug, alterations in PBPs that reduce their affinity for cephalothin, and changes in bacterial cell wall permeability. Proper antibiotic stewardship and adherence to dosing regimens are essential to minimize the development and spread of resistant strains.

Chemical and Physical Properties

Cephalothin has a molecular weight of 396.44 g/mol and is a white to off-white crystalline powder. It is slightly soluble in water and has limited stability in aqueous solutions. Cephalothin should be stored at controlled room temperature and protected from light.

Synthesis and Production

Cephalothin is synthesized from cephalosporin C, a natural product derived from the fungus Acremonium chrysogenum. The semisynthetic process involves the acylation of 7-aminocephalosporanic acid (7-ACA) with thiophene-2-acetyl chloride, followed by the removal of the protecting group.

Research and Development

Ongoing research focuses on enhancing the efficacy and reducing the side effects of cephalothin. Studies on liposome-encapsulated antibiotics have shown promise in improving the targeted delivery and reducing the toxicity of cephalothin. Additionally, co-opting strategies, such as the use of β-lactamase inhibitors, are being investigated to overcome antibiotic resistance.