Cross-over study of the pharmacokinetics of cefonicid administered intravenously or intramuscularly to healthy adult humans

Pharmacokinetics of cefonicid in lactating goats after intravenous, intramuscular and subcutaneous administration, and after a long-acting formulation for subcutaneous administration

The single-dose disposition kinetics of cefonicid were determined in clinically normal lactating goats (n = 6) after intravenous (IV), intramuscular (IM) and subcutaneous (SC) administration of a conventional formulation, and after subcutaneous administration of a long-acting formulation (SC-LA). Cefonicid concentrations were determined by high performance liquid chromatography with ultraviolet detection. The concentration-time data were analysed by noncompartmental pharmacokinetic methods. Steady-state volume of distribution (V_ss ) and clearance (Cl) of cefonicid after IV administration were 0.14 ± 0.03 L/kg and 0.51 ± 0.07 L/h·kg, respectively. Following IM, SC and SC-LA administration, cefonicid achieved maximum plasma concentrations of 14.46 ± 0.82, 11.98 ± 1.92 and 17.17 ± 2.45 mg/L at 0.26 ± 0.13, 0.42 ± 0.13 and 0.83 ± 0.20 hr, respectively. The absolute bioavailabilities after IM, SC and SC-LA routes were 75.34 ± 11.28%, 71.03 ± 19.14% and 102.84 ± 15.155%, respectively. After cefonicid analysis from milk samples, no concentrations were found above LOQ at any sampling time. From these data, cefonicid administered at 20 mg/kg each 12 hr after SC-LA could be effective to treat bacterial infections in lactating animals not affected by mastitis problems.

Influence of the ischaemic tourniquet in antibiotic prophylaxis in total knee replacement

OBJECTIVE

There is level iv evidence that the preoperative administration of antibiotics helps in the prevention of prosthetic infection. There is controversy on whether the ischemia applied during surgery may affect the minimum inhibitory concentration of the antibiotic in the peri-prosthetic tissues. The aim of this study is to review this phenomenon through the determination of antibiotic concentration in the synovial tissue.

MATERIAL AND METHOD

A prospective observational clinical study was conducted on 32 patients undergoing total knee replacement. Cefonicid 2g was administered as prophylaxis, with a tourniquet used for all patients. The antibiotic concentration was quantified by high performance liquid chromatography in samples of synovial tissue collected at the beginning and at the end of the intervention.

RESULTS

The mean concentration of antibiotic was 23.16 μg/g (95% CI 19.19 to 27.13) in the samples at the beginning of the intervention and 15.45 μg/g (95% CI 13.20 to 17.69) in the final samples, being higher than the minimum inhibitory concentration of cefonicid, set at 8 μg/g. These results were statistically significant for both concentrations (P<.00001).

DISCUSSION

The antibiotic concentration throughout the standard total knee prosthesis surgery performed with tourniquet gradually decreases throughout the intervention. The concentration determined at the end of the intervention was higher than the minimum inhibitory concentration required for the antibiotic studied. In conclusion, the use of a tourniquet does not increase the risk of infection.

Interaction of beta-lactam antibiotics with the mitochondrial carnitine/acylcarnitine transporter

The interaction of beta-lactams with the purified mitochondrial carnitine/acylcarnitine transporter reconstituted in liposomes has been studied. Cefonicid, cefazolin, cephalothin, ampicillin, piperacillin externally added to the proteoliposomes, inhibited the carnitine/carnitine antiport catalysed by the reconstituted transporter. The most effective inhibitors were cefonicid and ampicillin with IC50 of 6.8 and 7.6mM, respectively. The other inhibitors exhibited IC50 values above 36 mM. Kinetic analysis performed with cefonicid and ampicillin revealed that the inhibition is completely competitive, i.e., the inhibitors interact with the substrate binding site. The Ki of the transporter is 4.9 mM for cefonicid and 9.9 mM for ampicillin. Cefonicid inhibited the transporter also on its internal side. The IC50 was 12.9 mM indicating that the inhibition was less pronounced than on the external side. Ampicillin and the other inhibitors were much less effective on the internal side. The beta-lactams were not transported by the carnitine/acylcarnitine transporter. Cephalosporins, and at much lower extent penicillins, caused irreversible inhibition of the transporter after prolonged time of incubation. The most effective among the tested antibiotics was cefonicid with IC50 of 0.12 mM after 60 h of incubation. The possible in vivo implications of the interaction of the beta-lactam antibiotics with the transporter are discussed.

Cefonicid. A review of its antibacterial activity, pharmacological properties and therapeutic use

Cefonicid is a 'second generation' cephalosporin administered intravenously or intramuscularly. It is similar to cefamandole in its superiority to first generation cephalosporins against several enterobacteriaceae as well as its activity against Haemophilus influenzae, including beta-lactamase-producing strains. Its activity against Staphylococcus aureus is similar to that of cefoxitin and inferior to cefamandole and first generation cephalosporins. It has excellent in vitro activity against Neisseria gonorrhoeae, but is inactive against Pseudomonas, Acinetobacter, Serratia, and Bacteroides fragilis. Due to high achievable plasma concentrations and a relatively long half-life, in most clinical trials cefonicid has been administered once daily. It was comparable in efficacy with cefamandole or cefazolin in the treatment of patients with urinary tract, lower respiratory tract, and soft tissue and bone infections. It has also been compared with penicillin in the treatment of uncomplicated gonorrhoea. Results from a small series of patients with endocarditis appear to indicate that cefonicid should not be used in patients with serious staphylococcal infections. Single doses of cefonicid given preoperatively appear to offer a similar degree of protection against post-surgical infection as multiple doses of other antibiotics, but further data from studies involving larger numbers of patients are needed to confirm these impressions. Patients who require prolonged antibiotic therapy, such as those with osteomyelitis being treated as outpatients after a relatively short inpatient course, could benefit from the once daily dose regimen of cefonicid.