Plasma, bone, hip capsule and drain fluid concentrations of ampicillin and flucloxacillin during total hip replacement after intravenous bolus injection of magnapen.

1. A rapid intravenous bolus injection of 4.0 g Magnapen (which contains 2.0 g of ampicillin and 2.0 g of flucloxacillin) was to seven patients undergoing total hip replacement immediatly before induction of general anesthesia. Postoperatively the patients patients received 2.0 g Magnapen by intramuscular injection every 6 h for up to 72 h until removal of the wound drains. 2. The plasma, bone, hip capsule and drain fluid concentrations of ampicillin and flucloxacillin were measured by a differential small plate microbiological assay method using Sarcina lutea and a penicillinase producing Staph. aureus Russell as the test organisms. 3. The mean +/- s.e. mean concentrations of ampicillin after this regimen were 4222.2 +/- 285.0 microgram/ml (plasma), 65.6 +/- 1.3 microgram (g (hip capsule), 19.1 +/- 3.8 microgram/g (cancellous bone), and 211.1 +/- 65.6 microgram/g (ground up bone) respectively. 4. The mean +/- s.e. mean flucloxacillin concentrations after this regime were 137.2 +/- 28.4 microgram/ml (plasma), 61.8 +/- 15.0 microgram/g (hip capsule), 47.1 +/- 9.5 microgram/g (cancellous bone) and 139.4 +/- 21.8 microgram/g (ground up bone) respectively. 5. An intravenous bolus injection of Magnepen (4.0 g), given immediately before induction of general anaesthesia, provides concentrations of ampicillin and flucloxacillin in plasma, hip capsule, cancellous and ground up bone, and drain fluid that exceed the MICs of these antibiotics against Staph. aureus and E. coli. 6. The plasma, hip capsule, cancellous and ground up bone concentrations of ampicillin after this dose of Magnapen do not, however, exceed the MICs of the Gram negative anaerobes that sometimes cause postoperative wound infections in these patients.

Plasma, bone, hip capsule, synovial and drain fluid concentrations of lincomycin during total hip replacement.

1 Lincomycin (600 mg) was given 6 h preoperatively by intramuscular injection, as an intravenous infusion over 30 min and for 72 h postoperatively in twelve patients having total hip replacement. 2 The plasma, bone, hip capsule, synovial and drain fluid concentrations of lincomycin were almost always above the M.I.C. of lincomycin against penicillinase producing Staphylococcus aureus. 3 There was a good correlation between the estimated concentrations of lincomycin in bone by the grinding and agitation methods of analysis. 4 Two patients developed pseudomembranous colitis after parenteral lincomycin.

Pharmacokinetics of pivmecillinam.

1 The plasma concentration/time curves of ampicillin and mecillinam in normal subjects were measured after oral administration of ampicillin (500 mg) and pivmecillinam (400 and 600 mg). 2 Similar plasma concentration/time curves of ampicillin and mecillinam in the starved normal subjects followed oral administration of ampicillin (500 mg) and pivmecillinam (600 mg). 3 The plasma concentration/time curve of mecillinam was measured in the same normal subjects after oral administration of pivmecillinam (400 mg) with a reproducible standardized Lundh test meal. 4 There was no statistically significant difference in the plasma concentration/time curve of mecillinam after pivmecillinam/400 mg) and the meal compared with the plasma concentration/time curve after oral pivmecillinam (400 mg) was given to the same subjects when starved. After administration of pivmecillinam (400 mg) with meal, Tasc was significantly delayed beyond the value obtained when the subjects were starved. 5 The pharmacokinetics of pivmecillinam in coeliac disease are normal. This finding contrasts with previous studies on the pharmacokinetics of another pivaloyloxymethylpenicillin ester, pivampicillin, in this condition.