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

Pharmacokinetics and bone tissue concentrations of lincomycin following intravenous and intramuscular administrations to cats

The pharmacokinetic properties and bone concentrations of lincomycin in cats after single intravenous and intramuscular administrations at a dosage rate of 10 mg/kg were investigated. Lincomycin minimum inhibitory concentration (MIC) for some gram-positive strains isolated from clinical cases was determined. Serum lincomycin disposition was best-fitted to a bicompartmental and a monocompartmental open models with first-order elimination after intravenous and intramuscular dosing, respectively. After intravenous administration, distribution was rapid (T(1/2(d)) = 0.22 ± 0.09 h) and wide as reflected by the volume of distribution (V((d(ss)))) of 1.24 ± 0.08 L/kg. Plasma clearance was 0.28 ± 0.09 L/h · kg and elimination half-life (T(1/2)) 3.56 ± 0.62 h. Peak serum concentration (C(max)), T(max), and bioavailability for the intramuscular administration were 7.97 ± 2.31 μg/mL, 0.12 ± 0.05 h, and 82.55 ± 23.64%, respectively. Thirty to 45 min after intravenous administration, lincomycin bone concentrations were 9.31 ± 1.75 μg/mL. At the same time after intramuscular administration, bone concentrations were 3.53 ± 0.28 μg/mL. The corresponding bone/serum ratios were 0.77 ± 0.04 (intravenous) and 0.69 ± 0.18 (intramuscular). Lincomycin MIC for Staphylococcus spp. ranged from 0.25 to 16 μg/mL and for Streptococcus spp. from 0.25 to 8 μg/mL.

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 concentration/time curve of erythromycin after a 12-hour intravenous infusion of erythromycin lactobionate in man

As the pharmacokinetics after a slow infusion had not previously been evaluated in the doses used in this study, it was decided to measure the plasma concentration/time curve after a twelve-hour intravenous infusion of 2·0 g of erythromycin lactobionate in 2 litres of 0·9% normal saline. Six healthy medical students with no past history of cardiovascular, renal, hepatic, metabolic or gastrointestinal disease and no past drug allergy participated. The concentration of erythromycin base in venous blood was measured by small plate microbiological assay. Venous blood was taken at zero, 15, 30, 45, 60 min and at 2, 3, 4, 6, 8, 12, 16, 20 and 24 hr after starting the infusions. Duplicate assays were performed on all plasma samples at Guy's and at the manufacturer's laboratories. A full haematological and biochemical screening profile was performed before and after the study.

The mean ± s.e. plasma erythromycin base concentration rose from 0·7 ± 0·2 μg/ml at 15 min to 6·06 ± 1·6 μg/ml at 1 hr. The peak plasma concentration was between 1·48 ± 0·25 μg/ml at 30 min and 7·21 ± 0·93 μg/ml at 4 hr. The plasma concentration at 12 hr was 6·17 ± 0·33 μg/ml, and fell to 0·37 ± 0·05 μg/ml at 24 hr.

These findings suggest that therapeutically effective plasma concentrations follow a slow intravenous infusion of erythromycin lactobionate. There was no evidence of adverse haematological or biochemical function in the tests of blood, hepatic or renal function, apart from two volunteers who vomited after the infusions were discontinued.