A rapid and sensitive LC–ESI-MS/MS method for detection and quantitation of methylprednisolone and methylprednisolone acetate in rat plasma after intra-articular administration

Methylprednisolone‐loaded PLGA microspheres: A new formulation for sustained release via intra‐articular administration. A comparison study with methylprednisolone acetate in rats

“…The ESI interface parameters were optimized as previously described. 8 Data processing was performed by the Xcalibur 2.0.7 version software.…”

“…In particular, MP-PLGA MS were weighted (5.88 mg) and suspended in the MS-vehicle to have 1 mg of MP/ 100 :L. Depo-Medrol R was diluted to inject a dose of MP equivalent to MP contained in MP-PLGA MS. For this purpose, a Depo-Medrol R vial (40 mg of MPA, equivalent to 36 mg of MP) was diluted (1:3.6, v/v) with the supernatant obtained by centrifugation of another Depo-Medrol R vial as previously reported. 8 In both cases (MP-PLGA MS and Depo-Medrol R ), 50 :L was injected in each hind leg.…”

“…100-:L plasma aliquots were treated as previously reported. 8 MPA and MP plasma levels were determined according to the method previously developed and validated. 8 Results are expressed as mean ± standard deviation.…”

“…8 MPA and MP plasma levels were determined according to the method previously developed and validated. 8 Results are expressed as mean ± standard deviation. Pharmacokinetic (PK) functions for Microsoft Excel (by Joel Usansky, Atul Desai, and Diane Tang-Liuwere) were used to analyze the plasma concentration versus time data and to calculate PK parameters.…”

“…A validated LC-ESI-MS/MS method was utilized to quantify the plasmatic concentrations of MP. 8 The pharmacokinetic parameters and the extra-articular effects were compared to those obtained after the administration of a commercially available suspension of MP acetate (MPA).…”