Development of a supercritical fluid chromatography-tandem mass spectrometry method for the determination of azacitidine in rat plasma and its application to a bioavailability study

Determination of 5-azacitidine in human plasma by LC-MS/MS: application to pharmacokinetics pilot study in MDS/AML patients

PURPOSE

Azacitidine (Vidaza®, AZA) is a mainstay for treating acute myeloid leukemia (AML) in patients unfit for standard induction and other myelodysplastic syndromes (MDS). However, only half of the patients usually respond to this drug and almost all patients will eventually relapse. Predictive markers for response to AZA are yet to be identified. AZA is metabolized in the liver by a single enzyme, cytidine deaminase (CDA). CDA is a ubiquitous enzyme coded by a highly polymorphic gene, with subsequent great variability in resulting activities in the liver. The quantitative determination of AZA in plasma is challenging due the required sensitivity and because of the instability in the biological matrix upon sampling, possibly resulting in erratic values.

METHODS

We have developed and validated following EMA standards a simple, rapid, and cost-effective liquid chromatography-tandem mass spectrometry method for the determination of azacitidine in human plasma.

RESULTS

After a simple and rapid precipitation step, analytes were successfully separated and quantitated over a 5-500 ng/mL range. The performance and reliability of this method were tested as part of an investigational study in MDS/AML patients treated with standard azacitidine (75 mg/m² for 7 days a week every 28 days).

CONCLUSION

Overall, this new method meets the requirements of current bioanalytical guidelines and could be used to monitor drug levels in MDS/AML patients.

Evaluation of polysaccharide-based chiral stationary phases in modern SFC-MS/MS for enantioselective bioanalysis

Aim: The applicability of polysaccharide-based chiral stationary phases in modern supercritical fluid chromatography (SFC)-MS/MS for chiral bioanalysis was evaluated. Materials & methods: Ten popular polysaccharide-based chiral stationary phases (CSPs) were tested using a set of 23 drugs against three cosolvents. The effect of temperature and backpressure on separation was examined. Results: The recommended order of CSPs for screening was determined. Methanol with 0.1% NH₄OH is proven to be the first choice of cosolvent. Temperature of 40°C and backpressure of 10 or 15 MPa are recommended starting conditions. Phospholipid elution profiles on the polysaccharide-based CSPs were reported for the first time under SFC conditions. Conclusion: A simplified screening protocol with straightforward method optimization approaches was generated for SFC chiral assay development in a reasonable time frame with a high success rate.

Enantioselective supercritical fluid chromatography–tandem mass spectrometry method for simultaneous estimation of risperidone and its 9-hydroxyl metabolites in rat plasma

Aim: Objective of the current work was to develop a ‘green chemistry’ compliant selective and sensitive supercritical fluid chromatography–tandem mass spectrometry method for simultaneous estimation of risperidone (RIS) and its chiral metabolites in rat plasma. Methodology & results: Agilent 1260 Infinity analytical supercritical fluid chromatography system resolved RIS and its chiral metabolites within runtime of 6 min using a gradient chromatography method. Using a simple protein precipitation sample preparation followed by mass spectrometric detection achieved a sensitivity of 0.92 nM (lower limit of quantification). With linearity over four log units (0.91–7500 nM), the method was found to be selective, accurate, precise and robust. Conclusion: The method was validated and was successfully applied for simultaneous estimation of RIS and 9-hydroxyrisperidone metabolites (R & S individually) after intravenous and per oral administration to rats.

The studies of PLGA nanoparticles loading atorvastatin calcium for oral administration in vitro and in vivo

A biodegradable poly(lactic-co-glycolic acid) loading atorvastatin calcium (AC) nanoparticles (AC-PLGA-NPs) were prepared by probe ultrasonication and evaporation method aiming at improving the oral bioavailability of AC. The effects of experimental parameters, including stabilizer species, stabilizer concentration and pH of aqueous phase, on particle size were also evaluated. The resultant nanoparticles were in spherical shape with an average diameter of 174.7 nm and a narrow particle size distribution. And the drug loading and encapsulation efficiency were about 8% and 71%, respectively. The particle size and polydispersion were almost unchanged in 10 days. The release curves of AC-PLGA-NPs in vitro displaying sustained release characteristics indicated that its release mechanisms were matrix erosion and diffusion. The pharmacokinetic study in vivo revealed that the C_max and AUC_0-∞ of AC-PLGA-NPs in rats were nearly 3.7-fold and 4.7-fold higher than that of pure atorvastatin calcium suspension. Our results demonstrated that the delivery of AC-PLGA-NPs could be a promising approach for the oral delivery of AC for enhanced bioavailability.