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Cephradine

Cephradine is a semisynthetic, first generation cephalosporin antibiotic.

Administration

Cephradine is administered orally. Cephradine also has been administered by IM or IV injection and by IV infusion, but a parenteral dosage form no longer is commercially available in the US.

Dosage

Adult Dosage

The usual adult oral dosage of cephradine for the treatment of skin and skin structure infections and respiratory tract infections (other than lobar pneumonia) is 250 mg every 6 hours or 500 mg every 12 hours.

For uncomplicated urinary tract infections, the usual adult oral dosage is 500 mg every 12 hours.

For lobar pneumonia and serious urinary tract infections (including prostatitis), the usual adult oral dosage is 500 mg every 6 hours or 1 g every 12 hours. For severe or chronic infections, dosage may be increased up to 1 g every 6 hours.

Pediatric Dosage

The usual oral dosage of cephradine for children 9 months of age or older is 25-50 mg/kg daily given in equally divided doses every 6 or 12 hours. For the treatment of otitis media, the usual pediatric dosage is 75-100 mg/kg daily given in equally divided doses every 6 or 12 hours.

The manufacturers state that the efficacy of twice daily dosage regimens in infants younger than 9 months of age has not been definitely established.

The American Academy of Pediatrics (AAP) states that children older than 1 month of age may receive oral cephradine in a dosage of 25-50 mg/kg daily given in 2-4 divided doses for the treatment of mild to moderate infections. Pediatric oral dosage should not exceed 4 g daily.

Dosage in Renal Impairment

When cephradine is used in patients with impaired renal function who are not undergoing dialysis, the manufacturer recommends that those with creatinine clearances exceeding 20 mL/minute should receive a dosage of 500 mg every 6 hours, those with creatinine clearances of 5-20 mL/minute should receive 250 mg every 6 hours, and those with creatinine clearances less than 5 mL/minute should receive 250 mg every 12 hours.

In patients undergoing chronic, intermittent hemodialysis, the manufacturer recommends that an initial 250-mg dose of cephradine should be given at the start of hemodialysis, then 250 mg should be given 12 hours later followed by 250 mg given 36-48 hours later. Dosage modification in children with renal impairment should be proportional to the weight of the child and the severity of the infection. Spectrum Based on its spectrum of activity, cephradine is classified as a first generation cephalosporin.

For information on the classification of cephalosporins and closely related b-lactam antibiotics based on spectra of activity, see Spectrum in the Cephalosporins General Statement 8:12.06.

Like other first generation cephalosporins (e.g., cefadroxil, cefazolin, cephalexin), cephradine is active in vitro against many gram-positive aerobic cocci but has limited activity against gram-negative bacteria.

Pharmacokinetics

Absorption

Cephradine is acid-stable and is rapidly and almost completely absorbed from the GI tract. Following oral administration in healthy, fasting adults with normal renal function, peak serum cephradine concentrations are attained within 1 hour and average 9 mcg/mL following a single 250-mg dose, 15-18 mcg/mL following a single 500-mg dose, and 23.-24. mcg/mL following a single 1-g dose.

Cephradine

Peak serum concentrations are lower and are attained later when cephradine is administered with food, although the total amount of drug absorbed is unchanged. In one study in children 9-14 years of age with normal renal function, mean peak serum concentrations of cephradine occurred at 30 minutes and averaged 8.2 mcg/mL after a single 125-mg dose as the oral suspension and 15. mcg/mL after a single 250-mg dose as the oral suspension.

Although peak serum concentrations of the drug are higher and are attained sooner following administration of cephradine oral suspension than following administration of cephradine capsules, the difference is not considered clinically important.

Cephradine

Following IM administration (a parenteral dosage form is no longer commercially available in the US) in healthy adults with normal renal function, peak serum cephradine concentrations occur within 1-2 hours and average 5.8-6. mcg/mL following a single 500-mg dose and 9.9-13. mcg/mL following a single 1-g dose. Cephradine has been absorbed more slowly and serum concentrations have been lower in women than in men when the drug has been administered into the gluteus maximus.

No important differences in serum concentrations in men and women have occurred when cephradine has been given into the vastus lateralis or deltoid muscles.

Following direct IV administration (a parenteral dosage form is no longer commercially available in the US) of 1 g of cephradine in adults with normal renal function, serum concentrations of the drug average 86 mcg/mL at 5 minutes, 50 mcg/mL at 15 minutes, 26 mcg/mL at 30 minutes, 12 mcg/mL at 60 minutes, and 1 mcg/mL at 4 hours.

Elimination

The serum half-life of cephradine is 0.7-2 hours in adults with normal renal function. In one limited study, the half-life was reported to range from 8.5-10 hours in adults with creatinine clearances of 11-20 mL/minute and up to 60 hours in adults with creatinine clearances less than 10 mL/minute.

Cephradine is excreted unchanged in the urine. About 60-90% or more of a single oral, IM, or IV dose (a parenteral dosage form is no longer commercially available in the US) is excreted within 6 hours in patients with normal renal function.

Peak urinary concentrations of cephradine of 1.6 mg/mL, 3.2 mg/mL, and 4 mg/mL have been reported in adults with normal renal function following oral administration of a single 250-mg, 500-mg, and 1-g dose, respectively. A mean urinary cephradine concentration of 313 mcg/mL has been reported in adults with normal renal function during the 6-hour period following administration of a single 500-mg IM dose (a parenteral dosage form is no longer commercially available in the US).

Chemistry and Stability

Chemistry

Cephradine is a semisynthetic cephalosporin antibiotic. Cephradine occurs as a white to off-white, crystalline powder and is sparingly soluble in water and very slightly soluble in alcohol.

Stability

Cephradine should be protected from excessive heat, concentrated light, or direct sunlight. Cephradine capsules and powder for oral suspension should be stored in tight containers at a temperature not higher than 30°C, preferably between 15-30°C.

After reconstitution, cephradine oral suspensions are stable for 7 days at room temperature or 14 days at 2-8°C. For further information on chemistry, mechanism of action, spectrum, resistance, pharmacokinetics, uses, cautions, drug interactions, laboratory test interferences, and dosage and administration of cephradine, see the Cephalosporins General Statement 8:12.06.

Preparations

Cephradine Oral Capsules 250 mg Velosef®, Bristol-Myers Squibb 500 mg Velosef®, Bristol-Myers Squibb For suspension 125 mg/5 mL Velosef®, Bristol-Myers Squibb 250 mg/5 mL Velosef®, Bristol-Myers Squibb

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