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Cefatrizine

Cefatrizine: A First-Generation Cephalosporin for Oral Antibacterial Therapy

Introduction

Cefatrizine is an oral first-generation cephalosporin antibiotic, structurally and functionally related to other beta-lactam antibiotics such as cefadroxil and cephalexin. Although it is not as widely known or prescribed as some of its counterparts, Cefatrizine holds value in managing uncomplicated bacterial infections, particularly in the respiratory and urinary tracts. With its favorable pharmacokinetic profile, broad Gram-positive coverage, and oral bioavailability, Cefatrizine serves as an effective outpatient antimicrobial therapy. Originally introduced in the 1970s, Cefatrizine has seen variable usage across global markets. While not widely used in some countries due to the dominance of other cephalosporins, it remains an option where available. This article explores Cefatrizine’s chemical structure, mechanism of action, indications, efficacy, safety, resistance profile, and clinical relevance in modern medicine.

Overview of Cefatrizine

  • Chemical Class: First-generation cephalosporin

  • IUPAC Name: (6R,7R)-7-[(2Z)-2-(2-Amino-1,3-thiazol-4-yl)-2-methoxyiminoacetamido]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

  • Chemical Formula: C18H18N6O5S2

  • Molecular Weight: Approximately 462.5 g/mol

  • Route of Administration: Oral

Mechanism of Action

Cefatrizine, like other beta-lactam antibiotics, exerts its antibacterial effect by inhibiting bacterial cell wall synthesis. Specifically, it binds to penicillin-binding proteins (PBPs)—key enzymes in the synthesis of the bacterial peptidoglycan layer. By blocking these PBPs, Cefatrizine disrupts the integrity of the bacterial cell wall, leading to osmotic instability and cell lysis.

This bactericidal action is time-dependent, meaning its efficacy is related to the duration the drug concentration remains above the minimum inhibitory concentration (MIC) for the target pathogen.

Spectrum of Activity

Cefatrizine is most effective against Gram-positive bacteria and a limited range of Gram-negative organisms. Its primary targets include:

Gram-Positive Coverage

  • Streptococcus pyogenes

  • Staphylococcus aureus (methicillin-sensitive strains)

  • Streptococcus pneumoniae

Gram-Negative Coverage

  • Escherichia coli

  • Proteus mirabilis

  • Klebsiella pneumoniae (non-ESBL-producing)

Not Effective Against

  • MRSA

  • Pseudomonas aeruginosa

  • Anaerobic bacteria

  • Atypical organisms (e.g., Mycoplasma, Chlamydia)

Pharmacokinetics and Pharmacodynamics

Cefatrizine is orally bioavailable and demonstrates favorable pharmacokinetics, making it suitable for outpatient therapy.

Pharmacokinetic Parameter Value
Bioavailability ~95%
Time to Peak Concentration 1–2 hours
Half-life ~1–1.5 hours
Protein Binding 20–40%
Elimination Route Primarily renal (unchanged in urine)

This pharmacokinetic profile allows for twice-daily dosing in most clinical scenarios and contributes to high drug concentrations in urine, skin, and respiratory secretions.

Formulations and Dosage

Cefatrizine is typically available in oral forms:

  • Capsules: 250 mg, 500 mg

  • Oral Suspension: 125 mg/5 mL, 250 mg/5 mL

Standard Dosing

  • Adults: 500 mg every 12 hours

  • Children: 20–40 mg/kg/day in divided doses every 12 hours

  • Duration of therapy generally ranges from 5–10 days depending on the infection.

Dose Adjustments

  • Renal Impairment: Dose adjustment is required in patients with significant renal dysfunction.

Clinical Indications

Cefatrizine is used for the treatment of mild to moderate infections caused by susceptible organisms. Indications include:

1. Upper Respiratory Tract Infections

  • Pharyngitis and tonsillitis due to Streptococcus pyogenes

  • Sinusitis

  • Otitis media

Cefatrizine is a viable alternative in patients who are allergic to penicillin (without anaphylactic reaction).

2. Lower Respiratory Tract Infections

  • Bronchitis (acute or chronic exacerbations)

  • Community-acquired pneumonia (CAP) in mild cases caused by susceptible strains

3. Urinary Tract Infections

  • Cystitis

  • Asymptomatic bacteriuria

  • Uncomplicated lower UTIs, particularly in women

4. Skin and Soft Tissue Infections

  • Impetigo

  • Erysipelas

  • Folliculitis

  • Cellulitis caused by S. aureus and S. pyogenes

5. Dental and Periodontal Infections

Cefatrizine has also been used for odontogenic infections when penicillins are not tolerated.

Clinical Efficacy

Multiple studies during the 1980s and 1990s demonstrated Cefatrizine’s efficacy in:

  • Treating streptococcal pharyngitis (similar to penicillin VK)

  • Resolving acute otitis media in children

  • Curing uncomplicated UTIs

Though not first-line in current guidelines due to availability and preference for other agents, Cefatrizine has proven non-inferior to cephalexin and amoxicillin in many trials.

Adverse Effects

Cefatrizine is generally well tolerated, but as with all antibiotics, side effects may occur.

Common Adverse Effects

  • Diarrhea

  • Nausea

  • Abdominal discomfort

  • Headache

Uncommon but Serious Reactions

  • Hypersensitivity reactions (rash, urticaria, pruritus)

  • Anaphylaxis (rare, mostly in penicillin-allergic individuals)

  • Clostridioides difficile-associated diarrhea (CDAD)

Hematologic

  • Transient leukopenia

  • Eosinophilia

Regular monitoring is not required unless long-term therapy is anticipated.

Drug Interactions

Cefatrizine is relatively free of major drug-drug interactions. However, some interactions to note:

  • Probenecid: Delays renal clearance and prolongs half-life.

  • Oral Contraceptives: Theoretical decrease in efficacy; backup contraception is recommended.

  • Antacids or Iron: May reduce absorption slightly, though not always clinically relevant.

Use in Special Populations

Pediatrics

  • Safe and effective; oral suspension is easy to administer.

  • Dosing based on body weight.

Pregnancy

  • Classified as Category B; no known teratogenicity.

  • Safe in most cases when needed.

Lactation

  • Excreted in small amounts in breast milk.

  • Considered compatible with breastfeeding.

Geriatrics

  • Well tolerated but monitor renal function due to age-related decline in kidney performance.

Comparative Insights

Feature Cefatrizine Cefadroxil Cephalexin
Dosing Frequency Twice daily Once or twice daily 3–4 times daily
Common Indications ENT, UTI, SSTIs Pharyngitis, UTIs Skin, bone, dental
Bioavailability High (~95%) ~90% ~95%
MRSA Coverage No No No

While Cefatrizine offers similar efficacy, its less frequent dosing than cephalexin gives it a slight edge in adherence, especially in pediatric populations.

Resistance Considerations

Mechanisms of Resistance

  • Beta-lactamase production: Common in Gram-negative bacteria like E. coli, rendering Cefatrizine less effective.

  • Altered PBPs: Seen in resistant strains of S. pneumoniae.

  • Efflux Pumps: Contribute to reduced intracellular antibiotic concentration.

Resistance rates vary by region, and cultures are encouraged for recurrent or complicated infections.

Antimicrobial Stewardship and Guidelines

Cefatrizine is not usually listed as a first-line agent in contemporary IDSA or NICE guidelines, primarily due to:

  • Limited spectrum

  • Availability of broader-spectrum or more frequently studied alternatives

However, in the context of antimicrobial stewardship, Cefatrizine plays a valuable role by:

  • Targeting common pathogens without contributing to resistance in Pseudomonas or anaerobes

  • Being used for de-escalation from broad-spectrum IV therapy

  • Serving as a penicillin alternative

Market Availability and Global Use

While Cefatrizine is not available in the United States, it continues to be marketed and prescribed in parts of Europe, Asia, and Latin America. Its use is often region-specific and influenced by local prescribing habits, bacterial resistance patterns, and drug formulary status.

Conclusion

Cefatrizine is a safe, effective, and well-tolerated oral cephalosporin, particularly suited for the treatment of uncomplicated infections of the respiratory tract, urinary tract, and skin. While its clinical use has diminished in favor of better-known cephalosporins, Cefatrizine remains a valuable therapeutic option in regions where it is available. Given rising concerns over antimicrobial resistance, narrow-spectrum agents like Cefatrizine are critical in preserving the efficacy of broad-spectrum antibiotics. Clinicians should consider Cefatrizine when treating susceptible infections, especially in outpatient settings where oral therapy and high compliance are essential.