About

Cefdinir is a third-generation oral cephalosporin active against gram-positive cocci and common gram-negative pathogens including Haemophilus influenzae and Moraxella catarrhellae. Incorrect weight-based dosing in pediatric patients is the leading cause of antibiotic treatment failure and contributes to resistance selection pressure. The standard pediatric dose is 7 mg/kg once daily or 14 mg/kg/day divided every 12 hours, capped at the adult ceiling of 600 mg/day. This calculator applies FDA-approved labeling data to derive the exact suspension volume or capsule count for a given patient weight and indication.

Renal impairment alters clearance significantly. Patients with creatinine clearance < 30 mL/min require a 50% dose reduction. Hemodialysis removes cefdinir; a supplemental 300 mg dose is recommended after each session. This tool approximates dosing assuming normal hepatic function and no concomitant iron or antacid use, which reduce bioavailability by up to 80% if co-administered.

Formulas

The weight-based pediatric dose is computed as:

D = W × R

where D = single dose in mg, W = patient weight in kg, and R = rate constant (7 mg/kg for BID or 14 mg/kg for QD). The dose is capped so daily total does not exceed 600 mg.

Suspension volume is derived from the formulation concentration:

V = DC

where V = volume in mL and C = concentration (25 mg/mL for 125 mg/5 mL or 50 mg/mL for 250 mg/5 mL).

For renal impairment with creatinine clearance < 30 mL/min:

D_adj = D × 0.5

Pound-to-kilogram conversion uses the exact factor:

W_kg = W_lb × 0.45359237

Reference Data

Indication	Age Group	Dose	Frequency	Duration	Max Daily
Acute Bacterial Otitis Media	6 months - 12 years	7 mg/kg	Every 12 h	5 - 10 days	600 mg
Acute Bacterial Otitis Media	6 months - 12 years	14 mg/kg	Once daily	10 days	600 mg
Acute Maxillary Sinusitis	6 months - 12 years	7 mg/kg	Every 12 h	10 days	600 mg
Acute Maxillary Sinusitis	6 months - 12 years	14 mg/kg	Once daily	10 days	600 mg
Pharyngitis / Tonsillitis	6 months - 12 years	7 mg/kg	Every 12 h	5 - 10 days	600 mg
Pharyngitis / Tonsillitis	6 months - 12 years	14 mg/kg	Once daily	10 days	600 mg
Acute Bacterial Otitis Media	≥ 13 years / Adult	300 mg	Every 12 h	5 - 10 days	600 mg
Acute Maxillary Sinusitis	≥ 13 years / Adult	300 mg	Every 12 h	10 days	600 mg
Acute Maxillary Sinusitis	≥ 13 years / Adult	600 mg	Once daily	10 days	600 mg
Pharyngitis / Tonsillitis	≥ 13 years / Adult	300 mg	Every 12 h	5 - 10 days	600 mg
Community-Acquired Pneumonia	≥ 13 years / Adult	300 mg	Every 12 h	10 days	600 mg
Acute Exacerbation of Chronic Bronchitis	≥ 13 years / Adult	300 mg	Every 12 h	5 - 10 days	600 mg
Acute Exacerbation of Chronic Bronchitis	≥ 13 years / Adult	600 mg	Once daily	10 days	600 mg
Uncomplicated Skin / Skin Structure Infections	≥ 13 years / Adult	300 mg	Every 12 h	10 days	600 mg
Renal Impairment (CrCl < 30 mL/min)	All ages	50% of standard	Per indication	Per indication	300 mg
Hemodialysis Supplement	All ages	300 mg	After each session	As needed	-

Frequently Asked Questions

Concurrent administration of cefdinir with iron-containing products (including infant formula fortified with iron) reduces cefdinir bioavailability by up to 80%. Separate administration by at least 2 hours. Aluminum- and magnesium-containing antacids produce a similar effect. This calculator does not adjust for drug interactions; the prescriber must account for timing adjustments independently.

Cefdinir forms a non-absorbable complex with iron in the gastrointestinal tract, producing a reddish or rust-colored stool. This is not blood and has no clinical significance. It is most commonly seen in pediatric patients receiving iron-fortified formula alongside cefdinir suspension. No dose adjustment is required.

QD (once daily) dosing uses 14 mg/kg as a single dose (max 600 mg). BID (twice daily) uses 7 mg/kg per dose given every 12 hours (max 300 mg per dose). Both regimens produce equivalent clinical cure rates for otitis media, sinusitis, and pharyngitis per the FDA label. QD dosing may improve adherence in pediatric populations. BID dosing maintains more consistent serum levels and may be preferred in moderate-to-severe infections.

Hemodialysis removes approximately 63% of cefdinir from plasma. The initial dose should be 300 mg (or 7 mg/kg for pediatric patients), followed by 300 mg (or 7 mg/kg) after each dialysis session. On non-dialysis days, no additional dose is required. For peritoneal dialysis, the standard renal impairment dose (50% reduction) applies.

No. Cefdinir is FDA-approved for patients aged 6 months and older. Safety and efficacy have not been established in neonates or infants below 6 months. This calculator enforces a minimum age restriction and will not compute doses for this population. Consult neonatology guidelines for alternative cephalosporins.

For patients under 5 kg, calculated suspension volumes may fall below 1 mL, where oral syringe measurement error becomes proportionally significant. The calculator rounds to 0.1 mL precision. For weights below 3 kg, measurement variability can exceed 10% of the dose. Use a calibrated oral syringe (not a household teaspoon) and verify with pharmacy-grade measuring devices.