Cefdinir

• Acute Bacterial Sinusitis
• Otitis Media (Ear Infections)
• Community-Acquired Pneumonia
• Pharyngitis and Tonsillitis

Cefdinir is a third-generation oral cephalosporin antibiotic used to treat various bacterial infections. This broad-spectrum antibiotic is particularly valuable for treating respiratory tract infections and skin infections in both adults and children due to its favorable dosing schedule and tolerability.

Mechanism of Action

Cefdinir, like other cephalosporins, is a beta-lactam antibiotic that works by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) and inhibits the transpeptidation step of peptidoglycan synthesis, which is essential for maintaining bacterial cell wall integrity. This leads to cell wall weakening, osmotic instability, and ultimately bacterial cell death. Cefdinir is bactericidal against susceptible organisms and has good activity against Gram-positive bacteria (including Staphylococcus aureus and Streptococcus species) and many Gram-negative bacteria (including Haemophilus influenzae and Moraxella catarrhalis).

Available Formulations

Cefdinir is available as oral capsules (300 mg) and as an oral suspension (125 mg/5 mL and 250 mg/5 mL). The capsules and suspension can be taken with or without food. The suspension should be shaken well before each use and stored in the refrigerator. After reconstitution, the suspension is stable for 10 days.

Medical Uses

Cefdinir is FDA-approved for the treatment of acute bacterial exacerbations of chronic bronchitis, acute maxillary sinusitis, community-acquired pneumonia, pharyngitis/tonsillitis, and uncomplicated skin and skin structure infections in adults and adolescents. In pediatric patients (6 months to 12 years), it is approved for acute bacterial otitis media, pharyngitis/tonsillitis, and uncomplicated skin infections. It is often used as a second-line agent when first-line antibiotics have failed or are contraindicated.

Dosing Guidelines

For adults and adolescents, the typical dose is 300 mg twice daily or 600 mg once daily for 5-10 days depending on the infection. For pediatric patients, dosing is based on weight: 7 mg/kg twice daily or 14 mg/kg once daily (maximum 600 mg/day). Duration varies: 10 days for pharyngitis/tonsillitis, 10 days for acute bacterial sinusitis, 5-10 days for pneumonia, 10 days for skin infections. Dose adjustment is required for patients with significant renal impairment (CrCl less than 30 mL/min).

Important Safety Information

Cefdinir is contraindicated in patients with known allergy to cephalosporins. Cross-reactivity with penicillins exists but is relatively low (approximately 1-2%). The medication should be used with caution in patients with a history of severe penicillin allergy (anaphylaxis). Clostridioides difficile-associated diarrhea (CDAD) has been reported with nearly all antibiotics and may range from mild diarrhea to fatal colitis. Patients should be monitored for diarrhea during and after treatment.

Drug Interactions

Antacids containing magnesium or aluminum and iron supplements can significantly reduce cefdinir absorption; these should be taken at least 2 hours before or after cefdinir. Iron-fortified infant formulas may also reduce absorption. Probenecid inhibits renal excretion of cefdinir, increasing plasma levels. Cefdinir may cause a false-positive reaction for urine glucose tests using Clinitest tablets and potentially false-positive direct Coombs tests.

Special Populations

Cefdinir is pregnancy category B; it should be used during pregnancy only if clearly needed. It is excreted in human breast milk in small amounts and is generally considered compatible with breastfeeding. Safety and efficacy have been established in pediatric patients 6 months and older. Elderly patients may require dose adjustment if renal function is impaired. Dose reduction is recommended for patients with CrCl less than 30 mL/min (300 mg once daily for adults, 7 mg/kg once daily for children up to maximum 300 mg). Patients on hemodialysis should receive 300 mg or 7 mg/kg after each session.