What are the different types of oral cephalosporins (antibiotics) and their typical dosages?

Oral Cephalosporins: Complete List and Dosing

Oral cephalosporins are categorized into first-, second-, and third-generation agents, with first-generation agents (cephalexin, cefadroxil) preferred for streptococcal and staphylococcal infections, second-generation agents (cefuroxime, cefprozil, cefaclor) for enhanced gram-negative and β-lactamase-producing organisms, and third-generation agents (cefixime, cefdinir, cefpodoxime) reserved for resistant Enterobacteriaceae when narrower-spectrum options are inadequate. 1, 2

First-Generation Oral Cephalosporins

Cephalexin

• Adult dosing: 250 mg every 6 hours (standard); 500 mg every 12 hours for streptococcal pharyngitis, skin infections, and uncomplicated cystitis 3
• Pediatric dosing: 25-50 mg/kg/day divided into doses; for streptococcal pharyngitis and skin infections, may divide and give every 12 hours 3
• Severe infections: 75-100 mg/kg/day in 4 divided doses for otitis media 3
• Primary indications: Narrow-spectrum agent preferred for streptococcal pharyngitis and staphylococcal skin infections 1
• Limitations: Poor activity against H. influenzae, making it inappropriate for respiratory infections 2

Cefadroxil

• Dosing: Similar to cephalexin with once or twice daily administration 1
• Clinical use: Narrow-spectrum first-generation agent preferred over broad-spectrum alternatives for cost and resistance prevention 1

Second-Generation Oral Cephalosporins

Cefuroxime Axetil

• Adult dosing: 500 mg twice daily for outpatient infections 1, 4
• Clinical advantages: Enhanced activity against β-lactamase-producing H. influenzae, M. catarrhalis, and S. aureus 2
• Approved indications: Sinusitis (5-day course effective), respiratory infections, skin infections 1
• Key benefit: Twice-daily administration with enhanced gram-negative coverage compared to first-generation agents 2

Cefprozil

• Adult dosing: 500 mg every 12 hours 2
• Spectrum: Good activity against β-lactamase-producing H. influenzae, M. catarrhalis, and S. aureus 2

Cefaclor

• Adult dosing: 250 mg every 8 hours (standard); 500 mg every 8 hours for severe infections or less susceptible organisms 5
• Pediatric dosing: 20 mg/kg/day divided every 8 hours; 40 mg/kg/day (maximum 1 g/day) for serious infections, otitis media 5
• Alternative regimen: Total daily dose may be divided every 12 hours for otitis media and pharyngitis 5
• Important caveat: Higher risk of serum sickness-like reactions compared to other second-generation cephalosporins 2

Cefotiam Hexetil

• Dosing: Second-generation agent used in sinusitis 1
• Indication: Alternative for maxillary sinusitis 1

Third-Generation Oral Cephalosporins

Cefixime

• Classification: Broad-spectrum third-generation agent 1
• Guideline caution: Not preferred for routine streptococcal pharyngitis due to unnecessarily broad spectrum, higher cost, and increased selection for resistant flora 1

Cefdinir

• Classification: Broad-spectrum third-generation agent 1
• Guideline caution: More expensive than penicillin/amoxicillin and more likely to select for antibiotic-resistant flora 1

Cefpodoxime Proxetil

• Dosing: Used for sinusitis with 5-day courses shown effective 1
• Activity profile: Among the most active oral cephalosporins against viridans streptococci (comparable to ceftriaxone) 1
• Guideline caution: Broad-spectrum agent not recommended for routine streptococcal pharyngitis 1

Clinical Selection Algorithm

For Streptococcal Pharyngitis in Penicillin-Allergic Patients

• First choice: Narrow-spectrum cephalosporins (cephalexin or cefadroxil) strongly preferred over broad-spectrum agents 1
• Avoid: Broad-spectrum agents (cefaclor, cefuroxime, cefixime, cefdinir, cefpodoxime) due to higher cost and resistance selection 1
• Contraindication: Do not use in patients with immediate (anaphylactic-type) hypersensitivity to penicillin, as up to 10% are also allergic to cephalosporins 1

For Respiratory Infections

• Appropriate agents: Second-generation cephalosporins (cefuroxime, cefprozil) offer twice-daily dosing and enhanced activity against β-lactamase-producing organisms 2
• Avoid first-generation: Poor H. influenzae coverage makes first-generation agents inappropriate 2

For Sinusitis

• First-line options: Cefuroxime axetil, cefpodoxime proxetil, or cefotiam hexetil 1
• Duration: 7-10 days standard; 5-day courses effective for cefuroxime and cefpodoxime 1

For Endocarditis Prophylaxis (Dental Procedures)

• Penicillin-allergic patients: Cephalexin 2 g (adults) or 50 mg/kg (children) as single dose before procedure 1
• Alternative: Other first- or second-generation oral cephalosporins in equivalent dosage 1
• Contraindication: History of anaphylaxis, angioedema, or urticaria with penicillins 1

Critical Prescribing Considerations

Resistance Patterns

• Viridans streptococci resistance: Cephalexin shows 96% resistance in blood culture isolates, while cefpodoxime and ceftriaxone show only 17% resistance 1
• Clinical implication: First-generation oral cephalosporins may have limited efficacy despite in vitro susceptibility testing 1

Duration of Therapy

• Streptococcal infections: Minimum 10 days required for β-hemolytic streptococcal infections 3, 5
• Cystitis: 7-14 days 3

Common Pitfalls to Avoid

• Overuse of broad-spectrum agents: Prescribing third-generation cephalosporins for simple streptococcal pharyngitis increases cost and resistance without improving outcomes 1
• Ignoring allergy history: Cephalosporins carry 10% cross-reactivity in penicillin-allergic patients and are absolutely contraindicated in immediate hypersensitivity reactions 1
• Inadequate duration: Stopping β-hemolytic streptococcal treatment before 10 days risks treatment failure 3, 5