What is the first generation oral cephalosporin (1st gen oral ceph)?

First-Generation Oral Cephalosporins

First-generation oral cephalosporins include cephalexin (also spelled cefalexin) and cefadroxil, which are effective alternatives to penicillin for treating streptococcal and staphylococcal infections in penicillin-allergic patients without immediate hypersensitivity. 1, 2

Specific Agents and Clinical Context

The primary first-generation oral cephalosporins available are:

• Cephalexin (cefalexin): The most commonly used first-generation oral cephalosporin, available as capsules, tablets, and oral suspension 2
• Cefadroxil: Another first-generation agent with favorable pharmacokinetics that allows for less frequent dosing 3

Clinical Indications

First-generation oral cephalosporins are specifically indicated for:

• Penicillin-allergic patients with non-immediate hypersensitivity who require treatment for group A streptococcal pharyngitis (Category A, Grade II recommendation) 1
• Staphylococcal and streptococcal infections in patients who cannot tolerate penicillins 3, 4
• Surgical prophylaxis in appropriate clinical settings 3

The Infectious Diseases Society of America guidelines explicitly state that first-generation cephalosporins are acceptable alternatives for penicillin-allergic patients who do not manifest immediate hypersensitivity to β-lactam antibiotics 1

Dosing and Duration

For group A streptococcal pharyngitis, first-generation cephalosporins should be administered for 10 days to achieve maximal pharyngeal eradication, with the maximum daily dose being 1 gram per day 1

Critical Contraindications

First-generation cephalosporins must NOT be used in patients with immediate-type hypersensitivity reactions to β-lactam antibiotics (including anaphylaxis, angioedema, or urticaria), as cross-reactivity occurs in up to 10% of penicillin-allergic patients 5, 6

Antimicrobial Spectrum

First-generation cephalosporins maintain:

• Excellent activity against gram-positive cocci, particularly streptococci and staphylococci 3, 4
• Limited gram-negative coverage compared to later-generation agents 4, 7
• No activity against enterococci, which can lead to superinfection during treatment 3

Why Not First-Line?

Despite evidence suggesting cephalosporins may achieve superior bacteriologic eradication rates compared to penicillin 8, penicillin remains the drug of choice for non-allergic patients due to its proven efficacy, narrow spectrum, safety profile, and low cost 1, 5. Using broader-spectrum agents like cephalosporins as first-line therapy contributes to antimicrobial resistance and increased healthcare costs 5

Common Pitfalls to Avoid

• Do not use in patients with documented immediate penicillin allergy due to cross-reactivity risk 1, 5
• Do not use shorter courses than 10 days for streptococcal pharyngitis, as this may lead to treatment failure 1
• Do not select first-generation cephalosporins as first-line agents when penicillin can be used, as this promotes resistance 5
• Do not expect coverage of enterococci or Pseudomonas aeruginosa, as first-generation agents lack activity against these organisms 3