Is cefdinir (Cefdinir) more effective when taken once or twice daily?

Cefdinir Dosing: Once-Daily vs. Twice-Daily Administration

For most infections, cefdinir is more effective when administered twice daily rather than once daily, particularly for respiratory tract infections requiring optimal bacterial killing.

Dosing Recommendations by Infection Type

Respiratory Tract Infections

• Twice-daily dosing (7 mg/kg every 12 hours or 300 mg twice daily for adults) is preferred for respiratory tract infections requiring optimal bacterial killing 1
• In vitro pharmacodynamic models show that twice-daily cefdinir dosing regimens are more effective than once-daily regimens against common bacterial respiratory pathogens in producing 3-log killing and preventing regrowth at 24 hours 1
• For community-acquired pneumonia, twice-daily administration is likely the more appropriate cefdinir dosing strategy 1

Otitis Media and Sinusitis

• Both once-daily (14 mg/kg/day) and twice-daily (7 mg/kg every 12 hours) regimens are FDA-approved for acute bacterial otitis media and acute maxillary sinusitis 2
• However, once-daily dosing for 10 days has been shown to be as effective as twice-daily dosing for these conditions 2

Pharyngitis/Tonsillitis

• Both dosing regimens (once-daily 14 mg/kg/day or twice-daily 7 mg/kg every 12 hours) are considered effective for pharyngitis/tonsillitis 2
• Treatment duration ranges from 5-10 days for twice-daily dosing and 10 days for once-daily dosing 2

Skin and Skin Structure Infections

• Only twice-daily dosing (7 mg/kg every 12 hours) is recommended for uncomplicated skin and skin structure infections 2
• Once-daily dosing has not been studied in skin infections; therefore, cefdinir should be administered twice daily for these infections 2

Clinical Evidence Supporting Dosing Recommendations

• Cefdinir has shown good clinical and bacteriological efficacy in treating a wide range of mild-to-moderate infections when administered for 5 or 10 days 3
• In adults and adolescents, cefdinir is effective for both lower respiratory tract infections (acute bacterial exacerbations of chronic bronchitis, community-acquired pneumonia) and upper respiratory tract infections (acute bacterial rhinosinusitis, streptococcal pharyngitis) 3
• Cefdinir's pharmacokinetic profile allows for either once- or twice-daily administration, with a terminal disposition half-life of approximately 1.5 hours 4
• For sinusitis specifically, clinical trials have shown that cefdinir given once (600 mg) or twice daily (300 mg twice daily) was as effective clinically (approximately 90% cure rate) as amoxicillin-clavulanate given three times daily 5

Special Considerations

Renal Impairment

• For adult patients with creatinine clearance <30 mL/min, the dose should be reduced to 300 mg given once daily 2
• For pediatric patients with creatinine clearance <30 mL/min/1.73 m², the dose should be reduced to 7 mg/kg (up to 300 mg) given once daily 2

Hemodialysis Patients

• In patients on chronic hemodialysis, the recommended initial dosage is 300 mg or 7 mg/kg every other day 2
• At the conclusion of each hemodialysis session, 300 mg (or 7 mg/kg) should be given 2

Common Pitfalls and Caveats

• Diarrhea is the most common adverse event with cefdinir in clinical trials across all age groups 3
• The incidence of diarrhea in cefdinir recipients is generally higher than in adults and adolescents treated with comparator antibiotics 3
• Cefdinir may be administered without regard to meals, which improves compliance 2
• The suspension may be used for only 10 days after reconstitution, after which any unused portion must be discarded 2

In conclusion, while both once-daily and twice-daily dosing regimens are approved for most indications, twice-daily dosing provides more consistent bacterial killing for respiratory infections, and is the only studied and approved regimen for skin infections. The choice between once-daily and twice-daily dosing should be based on the specific infection being treated, with twice-daily dosing generally preferred for optimal antimicrobial effect.