Development, validation and application of a novel HPLC-MS/MS method for the measurement of minocycline in human plasma and urine

Hyaluronic acid-based minocycline-loaded dissolving microneedle: Innovation in local minocycline delivery for periodontitis

Periodontitis is a prevalent inflammatory disease that affects tooth-supporting tissues and is induced by complex polymicrobial dental plaques. Prior treatments, including topical antibiotic ointments, have faced difficulties in tissue permeability issues. Although dissolving microneedle (DMN) has been proposed as a painless and highly efficient transdermal drug delivery system to resolve this challenge, minocycline, widely used for the treatment of periodontitis, is light-sensitive, making it challenging to maintain its stability using conventional fabrication methods. Our hyaluronic acid-based minocycline-loaded dissolving microneedle (HAM-DMN) was designed utilizing an innovative light-blocking strategy, preserving 94.4 % of minocycline's stability, as confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. HAM-DMNs demonstrated antimicrobial efficacy in in vitro zone of inhibition tests with Streptococcus mutans strains and provided enhanced local delivery of minocycline to porcine oral gingival mucosa at concentrations 6.1 times higher than those of commercial ointments. In vivo studies in periodontitis-induced rat models showed that HAM-DMNs reduced levels of junctional epithelium more effectively than control and blank DMN groups, indicating enhanced treatment efficacy. HAM-DMN is a novel local delivery system developed to overcome the limitations of systemic delivery and conventional topical treatment. We suggest that HAM-DMNs can replace injections for the treatment of intraoral mucosal and systemic diseases.

Population pharmacokinetics/pharmacodynamics of minocycline plus rifampicin in patients with complicated skin and skin structure infections caused by MRSA

BACKGROUND

The population pharmacokinetics/pharmacodynamics (PK/PD) of minocycline, rifampicin and linezolid in patients with complicated skin and soft tissue infections (cSSTIs) caused by MRSA are described.

METHODS

Samples were collected in a Phase 4 study of oral minocycline plus rifampicin versus linezolid showing minocycline plus rifampicin to be non-inferior to linezolid. Antibiotics were assayed by HPLC or LC-MS, and a population PK model was developed using Pmetrics. The association between PK/PD indices and patient outcomes was explored.

RESULTS

A three-compartment model (with an absorption compartment) with first-order input and elimination best described the data for the three drugs. No covariates were included in the final model. The population median values (95% credibility limits) of the clearance and volume of distribution were 7.412 L/h (5.121-8.361) and 14.155 L (6.799-33.901) for minocycline, 5.683 L/h (3.703-7.726) and 7.736 L (6.031-8.948) for rifampicin, and 1.970 L/h (1.326-2.499) and 20.169 L (12.857-32.629) for linezolid, respectively. Maximum a posteriori probability-Bayesian estimation plots of observed versus predicted had a slope of 0.999 r20.967 for minocycline, slope 0.998 r20.769 for rifampicin and slope 0.998 r20.895 for linezolid. PK/PD indices were not related to clinical outcome. Taking a translational minocycline fAUC24h/MIC target of >0.5 for minocycline in the presence of rifampicin, 96% (49/51) of patients reached the target.

CONCLUSIONS

Population PK models of minocycline, rifampicin and linezolid were developed in patients with MRSA cSSTI and almost all patients reached the predefined PD index targets. As a result, neither AUC, MIC nor the AUC/MIC ratio could be related to clinical outcome.

Validation of a single UHPLC-MS/MS approach for oxytetracycline determination in bull plasma, seminal plasma and urine

Oxytetracycline is a broad‐spectrum antibiotic, which inhibits protein synthesis and is generally used for the treatment of pneumonia, shipping fever, leptospirosis and wound infections in cattle and swine. The present work proposes a novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for oxytetracycline quantification in bull plasma, seminal plasma and urine, requiring limited sample treatment before analysis. Extraction with trichloroacetic acid followed by dilution of the supernatant in mobile phase proved to be effective in all three matrices, allowing to rapidly process large batches of samples. Sharp and symmetrical peak shape was obtained using a BEH C18 reversed‐phase column in a chromatographic run of just 3.5 min. The mass spectrometer operated in positive electrospray ionization mode and monitored specific transitions for oxytetracycline (461.1 → 425.8) and the internal standard demeclocycline (465.0 → 447.6). The method was validated over concentration ranges suitable for field concentrations of oxytetracycline found in each matrix, showing good linearity during each day of testing (R² always >0.99), as also confirmed by analysis of variance (ANOVA) and lack‐of‐fit tests. Excellent accuracy and precision were demonstrated by calculated bias always within ±15% and CV% below 10% at all quality control (QC) levels in the three matrices. Matrix effect and recovery were investigated for both analytes, which showed consistent and comparable behaviour in each matrix. To our knowledge, this is the first validated approach for mass spectrometric determination of oxytetracycline in seminal plasma and urine. The method was successfully applied to samples collected during a pharmacokinetic study in bulls, allowing to assess the oxytetracycline concentration–time profile in plasma, seminal plasma and urine.

A review of green solvent extraction techniques and their use in antibiotic residue analysis

Antibiotic residues are being continuously recognized in the aquatic environment and in food. Though the concentration of antibiotic residues is typically low, adverse effects on the environment and human health have been observed. Hence, an efficient method to determine numerous antibiotic residues should be simple, inexpensive, selective, with high throughput and with low detection limits. Liquid-based extractions have been exceedingly used for clean-up and preconcentration of antibiotics prior to chromatographic analysis. In order to make methods more green and environmentally sustainable, conventional hazardous organic solvents can be replaced with green solvents. This review presents sampling strategies as well as comprehensive and up-to-date methods for chemical analysis of antibiotic residues in different sample matrices. Particularly, solvent-based sample preparation techniques using green solvents are discussed along with applications in antibiotic residue analysis.

Pharmacokinetics and ex vivo pharmacodynamics of Minocycline against Salmonella abortus equi in donkey plasma and tissue cage fluid

Tissue Cage (TC) model was used to evaluate the pharmacokinetics and ex vivo pharmacodynamics of Minocycline (MINO) after intramuscular (IM) administration to donkeys at 4 mg/kg body-weight. The C_max of MINO with 1.79 and 2.63 μg mL^-1 was obtained at 2.96 and 1.41 h in TCF (tissue cage fluid) and plasma respectively. The absorption half-lives (t_1/2ka) of MINO were calculated to be 0.71 h in TCF and 0.32 h in plasma, whereas the elimination half-lives (t_1/2ke) were 10.46 h in TCF and 5.95 h in plasma. The distribution volume (V_d/F) of MINO was estimated to be 1.84 L kg^-1 in TCF and 1.28 L kg^-1 in plasma. The total clearance (CL_b/F) of MINO was computed as 0.12 and 0.15 L/ (h·kg) in TCF and plasma respectively. The area under the concentration-time curve (AUC) of MINO was 32.77 μg mL^-1h in TCF and 25.27 μg mL^-1h in plasma, respectively.The ex vivo time-kill curves were established for plasma and TCF samples using Salmonella abortus equi. The MIC and MBC of MINO against salmonella were 0.08 and 0.16 μg mL^-1 for plasma, 0.04 and 0.08 μg mL^-1 for TCF. The plasma C_max/MIC and AUC/MIC values after IM administration were 32.88 ± 9.87 and 315.88 ± 42.65 h, respectively. The TCF C_max/MIC and AUC/MIC values after IM administration were 44.75 ± 9.32 and 819.25 ± 65.23 h, respectively. The values of T > MIC were approximately >36 h in plasma and > 65 h in TCF. These findings from this study suggest that MINO may be therapeutically effective in diseases of donkeys caused by salmonella when used at a dose of 4 mg/kg IM administration.