CEFDINIR — cefdinir capsule
Physicians Total Care, Inc.
To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefdinir and other antibacterial drugs, cefdinir should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
Cefdinir capsules contain the active ingredient cefdinir, an extended-spectrum, semisynthetic cephalosporin, for oral administration. Chemically, cefdinir is [6R-[6α, 7β (Z)]]-7-[[(2-amino-4-thiazolyl)(hydroxyimino)acetyl]amino]-3-ethenyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid. Cefdinir is a white to slightly brownish-yellow solid. It is slightly soluble in dilute hydrochloric acid and sparingly soluble in 0.1 M pH 7 phosphate buffer. The molecular formula is C14
and the molecular weight is 395.42. Cefdinir has the structural formula shown below:
Cefdinir capsules contain 300 mg cefdinir and the following inactive ingredients: carboxymethylcellulose calcium, colloidal silicon dioxide and magnesium stearate. The empty hard gelatin capsule shells contain FD&C Blue #1, D&C Red #28, titanium dioxide, gelatin and sodium lauryl sulphate. The capsules are printed with edible ink containing black iron oxide and shellac.
Pharmacokinetics and Drug Metabolism
Maximal plasma cefdinir concentrations occur 2 to 4 hours postdose following capsule or suspension administration. Plasma cefdinir concentrations increase with dose, but the increases are less than dose-proportional from 300 mg (7 mg/kg) to 600 mg (14 mg/kg). Following administration of suspension to healthy adults, cefdinir bioavailability is 120% relative to capsules. Estimated bioavailability of cefdinir capsules is 21% following administration of a 300 mg capsule dose, and 16% following administration of a 600 mg capsule dose. Estimated absolute bioavailability of cefdinir suspension is 25%. Cefdinir oral suspension of 250 mg/5 mL strength was shown to be bioequivalent to the 125 mg/5 mL strength in healthy adults under fasting conditions.
Effect of Food
and AUC of cefdinir from the capsules are reduced by 16% and 10%, respectively, when given with a high-fat meal. In adults given the 250 mg/5 mL oral suspension with a high-fat meal, the Cmax
and AUC of cefdinir are reduced by 44% and 33%, respectively. The magnitude of these reductions is not likely to be clinically significant because the safety and efficacy studies of oral suspension in pediatric patients were conducted without regard to food intake. Therefore, cefdinir may be taken without regard to food.
Cefdinir plasma concentrations and pharmacokinetic parameter values following administration of single 300 and 600 mg oral doses of cefdinir to adult subjects are presented in the following table:
Mean (±SD) Plasma Cefdinir Pharmacokinetic Parameter Values Following Administration of Capsules to Adult Subjects
|Dose||Cmax (mcg/mL) ||Tmax (hr)||AUC(mcg•hr/mL) |
| 300 mg ||1.6(0.55)||2.9(0.89)||7.05(2.17)|
| 600 mg ||2.87(1.01)||3(0.66)||11.1(3.87)|
Cefdinir plasma concentrations and pharmacokinetic parameter values following administration of single 7 and 14 mg/kg oral doses of cefdinir to pediatric subjects (age 6 months to 12 years) are presented in the following table:
Mean (±SD) Plasma Cefdinir Pharmacokinetic Parameter Values Following Administration of Suspension to Pediatric Subjects
|Dose||Cmax (mcg/mL) ||tmax (hr)||AUC(mcg•hr/mL) |
| 7 mg/kg ||2.3(0.65)||2.2(0.6)||8.31(2.5)|
| 14 mg/kg ||3.86(0.62)||1.8(0.4)||13.4(2.64)|
Cefdinir does not accumulate in plasma following once- or twice-daily administration to subjects with normal renal function.
The mean volume of distribution (Vdarea
) of cefdinir in adult subjects is 0.35 L/kg (±0.29); in pediatric subjects (age 6 months to 12 years), cefdinir Vdarea
is 0.67 L/kg (±0.38). Cefdinir is 60% to 70% bound to plasma proteins in both adult and pediatric subjects; binding is independent of concentration.
In adult subjects, median (range) maximal blister fluid cefdinir concentrations of 0.65 (0.33 to 1.1) and 1.1 (0.49 to 1.9) mcg/mL were observed 4 to 5 hours following administration of 300 and 600 mg doses, respectively. Mean (±SD) blister Cmax
values were 48% (±13) and 91% (±18) of corresponding plasma values.
In adult patients undergoing elective tonsillectomy, respective median tonsil tissue cefdinir concentrations 4 hours after administration of single 300 and 600 mg doses were 0.25 (0.22 to 0.46) and 0.36 (0.22 to 0.8) mcg/g. Mean tonsil tissue concentrations were 24% (±8) of corresponding plasma concentrations.
In adult patients undergoing elective maxillary and ethmoid sinus surgery, respective median sinus tissue cefdinir concentrations 4 hours after administration of single 300 and 600 mg doses were <0.12 (<0.12 to 0.46) and 0.21 (<0.12 to 2) mcg/g. Mean sinus tissue concentrations were 16% (±20) of corresponding plasma concentrations.
In adult patients undergoing diagnostic bronchoscopy, respective median bronchial mucosa cefdinir concentrations 4 hours after administration of single 300 and 600 mg doses were 0.78 (<0.06 to 1.33) and 1.14 (<0.06 to 1.92) mcg/mL, and were 31% (±18) of corresponding plasma concentrations. Respective median epithelial lining fluid concentrations were 0.29 (<0.3 to 4.73) and 0.49 (<0.3 to 0.59) mcg/mL, and were 35% (±83) of corresponding plasma concentrations.
Middle Ear Fluid
In 14 pediatric patients with acute bacterial otitis media, respective median middle ear fluid cefdinir concentrations 3 hours after administration of single 7 and 14 mg/kg doses were 0.21 (<0.09 to 0.94) and 0.72 (0.14 to 1.42) mcg/mL. Mean middle ear fluid concentrations were 15% (±15) of corresponding plasma concentrations.
Data on cefdinir penetration into human cerebrospinal fluid are not available.
Metabolism and Excretion
Cefdinir is not appreciably metabolized. Activity is primarily due to parent drug. Cefdinir is eliminated principally via renal excretion with a mean plasma elimination half-life (t½
) of 1.7 (±0.6) hours. In healthy subjects with normal renal function, renal clearance is 2 (±1) mL/min/kg, and apparent oral clearance is 11.6 (±6) and 15.5 (±5.4) mL/min/kg following doses of 300 and 600 mg, respectively. Mean percent of dose recovered unchanged in the urine following 300 and 600 mg doses is 18.4% (±6.4) and 11.6% (±4.6), respectively. Cefdinir clearance is reduced in patients with renal dysfunction (see Special Populations: Patients with Renal Insufficiency
).Because renal excretion is the predominant pathway of elimination, dosage should be adjusted in patients with markedly compromised renal function or who are undergoing hemodialysis (see DOSAGE AND ADMINISTRATION
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