Pharmacology: Pharmacokinetics: Cefradine is rapidly and almost complete absorbed from the gastrointestinal tract after oral doses. Doses of 0.25, 0.5, and 1 g given orally have produced peak plasma concentration of about 9, 17, and 24 micrograms/mL respectively at 1 hour and are similar to those achieved with cephalexin. Absorption is delayed by the presence of food although the total amount absorbed altered. Following intramuscular injection peak plasma concentrations of about 6 and 14 micrograms/mL have been obtained within 1 to 2 hours of doses of 0.5 and 1 g respectively. Only about 8 to 12% reported to be bound to plasma proteins. A plasma half-life of about 1 hour has been reported; this is prolonged in patients with renal impairment. Cefradine is widely distributed to body tissues and fluids, but does not enter the CSF in significant quantities. Therapeutic concentrations may be found in the bile. It crosses the placenta into the fetal circulation and is distributed in small amounts into breastmilk.
Microbiology: Antimicrobial Action: Some strains of Gram-negative bacteria may be inhibited only by the high concentrations achievable in the urinary tract. It is most active against Gram-positive cocci, and has moderate activity against Gram-negative bacilli. Sensitive Gram-positive cocci include both penicillinase and non-penicillinase-producing staphylococci, although methicillin-resistant staphylococci are resistant; most streptococci are also sensitive, but not penicillin-resistant Streptococcus pneumoniae; enterococci are usually resistant. Some gram-positive anaerobes are also susceptible.
Among Gram-negative bacteria Cefradine has activity against some Enterobacteriaceae including strains of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Salmonella, and Shigella spp., but not against Enterobacter, indole-positive Proteus, or Serratia spp. It is also active against Moraxella catarrhalis (Branhamella catarrhalis) and Neisseria spp., though Haemophilus influenzae is moderately resistant. Bacteroides fragilis and Pseudomonas aeruginosa are not sensitive and neither are mycobacteria, mycoplasma, and fungi.