Development and validation of LC-MS/MS methods to measure tobramycin and lincomycin in plasma, microdialysis fluid and urine: application to a pilot pharmacokinetic research study.

Background The aim of our work was to develop and validate a hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry (HILIC-ESI-MS/MS) methods for the quantification of tobramycin (TMC) and lincomycin (LMC)in plasma, microdialysis fluid and urine. Methods Protein precipitation was used to extract TMC and LMC from plasma, while microdialysis fluid and urine sample were diluted prior to instrumental analysis. Mobile phase A consisted of 2 mM ammonium acetate in 10% acetonitrile with 0.2% formic acid (v/v) and mobile phase B consisted of 2 mM ammonium acetate in 90% acetonitrile with 0.2% formic acid (v/v). Gradient separation (80%-10% of mobile phase B) for TMC was done using a SeQuant zic-HILIC analytical guard column. While separation of LMC was performed using gradient elution (100%-40% of mobile phase B) on a SeQuant zic-HILIC analytical column equipped with a SeQuant zic-HILIC guard column. Vancomycin (VCM) was used as an internal standard. A quadratic calibration was obtained over the concentration range for plasma of 0.1-20 mg/L for TMC and 0.05-20 mg/L for LMC, for microdialysis fluid of 0.1-20 mg/L for both TMC and LMC, and 1-100 mg/L for urine for both TMC and LMC. Results For TMS and LMC, validation testing for matrix effects, precision and accuracy, specificity and stability were all within acceptance criteria of ±15%. Conclusions The methods described here meet validation acceptance criteria and were suitable for application in a pilot pharmacokinetic research study performed in a sheep model.

High-Precision Quantitation of Biofluid Samples Using Direct Mass Spectrometry Analysis.

The transition of mass spectrometry for clinical analysis is highly desirable, and major progress has been made with direct sampling ionization for operation simplification. High-precision quantitation, however, remains a major challenge in this transition. Herein, a novel method was developed for direct quantitation of biofluid samples, using an extremely simplified procedure for incorporation of internal standards selected against the traditional rules. Slug flow microextraction was used for the development, with conditions predicted by a theoretical model, viz., using internal standards of partition coefficients very different from the analytes and large sample-to-extraction solvent volume ratios. Direct quantitation of drug compounds in urine and blood samples was demonstrated. This development enabled an extremely simplified protocol that is expected to have a significant impact on on-site or clinical analysis.

Pharmacokinetics of lincomycin following single intravenous administration in buffalo calves.

Lincomycin 10 mg kg(-1), IV in buffalo calves followed two-compartment open model with high distribution rate constant α (11.2 ± 0.42 h(-1)) and K 12/K 21 ratio (4.40 ± 0.10). Distribution half-life was 0.06 ± 0.01 h and AUC was 41.6 ± 1.73 µg mL(-1) h. Large Vdarea (1.15 ± 0.03 L kg(-1)) indicated good distribution of lincomycin in various body fluids and tissues. Peak plasma level of lincomycin (71.8 ± 1.83 µg mL(-1)) was observed at 1 min as expected by IV route. The elimination half-life and MRT of lincomycin were short (3.30 ± 0.08 and 4.32 ± 0.11 h, respectively). Lincomycin 10 mg kg(-1) IV at 12-h interval would be sufficient to maintain T > MIC above 60 % for bacteria with minimum inhibitory concentrations (MIC) values ≤1.6 µg mL(-1). Favourable pharmacokinetic profile in buffalo calves and a convenient dosing interval suggest that lincomycin may be an appropriate antibacterial in buffalo species for gram-positive and anaerobic bacterial pathogens susceptible to lincomycin.

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.

A flow injection chemiluminescence method for the determination of lincomycin in serum using a diperiodato-cuprate (III)-luminol system.

In this paper, the novel trivalent copper-periodate complex {K5[Cu(HIO6)2], DPC} has been applied in a luminol-based chemiluminescence (CL) reaction. Coupled with flow injection (FI) technology, the FI-CL method was proposed for the determination of lincomycin hydrochloride. The CL reaction between luminol and DPC occurred in an alkaline medium. The CL intensity could be greatly enhanced by lincomycin hydrochloride. The relative CL intensity was proportional to the concentration of lincomycin hydrochloride in the range of 1 × 10⁻8 to 5 × 10⁻6 g mL⁻¹ and the detection limit was at the 3.5 × 10⁻9 g mL⁻¹ level. The relative standard deviation at 5 × 10⁻8 g mL⁻¹ was 1.7% (n = 9). The sensitive method was successfully applied to the direct determination of lincomycin hydrochloride (ng mL⁻¹) in serum. A possible mechanism of the lumonol-DPC CL reaction was discussed by the study of the CL kinetic characteristics and the spectra of CL reaction. The oxidability of DPC was studied by means of its electrochemical response.

Establishment and validation of the LC-MS/MS method for the determination of lincomycin in human blood: Application to an allergy case in forensic science.

An analytical method to quantify lincomycin in human blood samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. The selected method was based on a protein precipitation extraction (PPE) with methanol. Instrumental determination was carried out by LC-MS/MS, with quantification based on the internal standard method. Linearity for lincomycin was established in the concentration range of 5-100 ng/mL. The limit of detection (LOD) and limit of quantification (LOQ) were 0.2 and 1 ng/mL, respectively. Analyte recoveries were in the range of 72.70%-84.13% for spiked blood samples. The accuracies ranged between 92.82% and 100.40%, and the intraday and inter-day precisions ranged between 1.19% and 6.40%, respectively. The developed method was applied to an authentic allergy case of lincomycin. By testing the lincomycin content in the venous blood of the deceased and combined with the pathological test results, lincomycin acute allergy appeared to be the most likely cause of death. The acquired results confirm that the developed method is capable of identifying and quantifying lincomycin in human blood and can be suitable for the detection of allergy cases in clinical or forensic science.

Protein binding and pharmacokinetics of lincomycin following intravenous administration of high doses.

High-dose infusions of lincomycin 600, 1,200, and 2,400 mg were administered to 14 healthy, adult men. Using model-independent pharmacokinetics, it was found that the half-life, mean residence time, and steady-state volume of distribution of total drug increased with dose, whereas the same parameters remained unchanged for the unbound lincomycin. Although the mean clearance value for total drug increased, this change fell short of being significant at the 5% level and was associated with a decrease in unbound clearance following administration of the 2,400 mg dose. Protein binding studies using ultrafiltration gave direct evidence of saturable serum protein binding and indicated that binding involved at least two distinct classes of binding sites.

Lincomycin serum and saliva concentrations after intramuscular injection of high doses.

Serum and saliva levels of lincomycin were determined in 15 normal adult male volunteers after a single intramuscular injection of 600, 1000, or 1500 mg lincomycin in a three-way crossover study. The area under the serum concentration-time curve did not increase in proportion to the increase in dose. The increase in concentration of lincomycin in saliva was greater than expected for the increase in dose. There were not significant differences in elimination half-life between doses. These results suggest that the apparent clearance of lincomycin increases with increasing dose possibly because of a decrease in serum protein binding of lincomycin at high serum concentrations.

Serum and peritoneal fluid concentrations of clindamycin and lincomycin in the mouse.

Serum concentrations of drug were obtained at various times after intramuscular dosing of healthy mice with either clindamycin or lincomycin hydrochlorides. Washings from the peritoneal cavity were taken at the same time as the serum samples. Changes in drug concentration in the peritoneal fluid with time mimic those for the serum, but concentrations in peritoneal fluid are much greater than the corresponding serum concentrations. The total volume of peritoneal fluid was estimated to be 0.05 ml.

A reliable two-hour Staphylococcus plate assay of rifampicin, erythromycin, lincomycin, chloramphenicol and amikacin in human sera.

A simple and precise agar diffusion microassay was developed for rifampicin (RIF) in serum. The method involved the addition of sera containing RIF (0.125-4.0 micrograms/ml) to wells cut in an agar medium (pH 6.6) surface seeded with an adjusted inoculum of Staphylococcus aureus ATCC 6538 P and incubated for 2h at 40 degrees C. Repetitive assays of sera containing known concentrations of RIF revealed an average mean recovery of 93.6% with a coefficient of variation of 5.7%. This rapid method allowed accurate determination of RIF in the presence of erythromycin, chloramphenicol, lincomycin and amikacin. These four antibiotics were also separately measured in sera by the rapid assay at different pH values.

[Prolonged regional intra-arterial therapy in multimodal treatment of patients with severe skeletal trauma]. / Dlitel'naia regionarnaia vnutriarterial'naia terapiia v komplekse lecheniia postradavshikh s tiazheloi skeletnoi travmoi.

A total of 108 victims with open fractures of long tubular bones of different localization are examined. Regional intraarterial therapy was added to their treatment protocols. Stable functional disorders in local hemodynamics in these patients impede the repair processes and can lead to development of infectious complications. Regional intraarterial therapy allows early elimination of hemodynamic disorders, selective antibiotic therapy, and improves the adaptation potential of the immune system.