Simultaneous determination of triamcinolone acetonide palmitate and triamcinolone acetonide in beagle dog plasma by UPLC-MS/MS and its application to a long-term pharmacokinetic study of triamcinolone acetonide palmitate lipid emulsion injection

• Development of a UPLC–MS/MS method to simultaneous determination of TAP and TA in beagle dog plasma for the first time.
• The LLOQs of TAP and TA were 1 and 0.5 ng/ml, respectively.
• The method was applied to a 28-day pharmacokinetic study of TAP and TA in beagle dogs.
• No accumulation and no significant differences on pharmacokinetic behavior of TAP and TA were observed.

In order to investigate the pharmacokinetics of triamcinolone acetonide palmitate (TAP) which is a lipid-soluble prodrug of triamcinolone acetonide (TA), a rapid, simple, sensitive and reproducible UPLC-MS/MS method has been developed and validated for the simultaneous determination of TAP and TA in beagle dog plasma. After simple liquid–liquid extraction, the analytes and internal standard (dexamethasone, DEX) were separated on Phenomenex Luna C18 column (50 mm × 2.1 mm, 1.7 μm) using a mobile phase consisting of solvent A (acetonitrile) and solvent B (0.1% ammonia solution) at a flow rate of 0.2 ml/min with gradient elution. Acquisition of mass spectrometric data was performed in multiple reaction monitoring (MRM) mode via positive electrospray ionization using the ion transitions of m/z 673.5 → 397.3, 435.3 → 415.3 and 393.3 → 355.3 for TAP, TA and IS, respectively. The method was of satisfactory specificity, sensitivity, precision and accuracy over the concentration range of 1–1000 ng/ml for TAP and 0.5–500 ng/ml for TA. The intra- and inter-day precisions for both TAP and TA were 3.2% to 18.7% and the accuracy was in the range of −8.4% to 6.8%. The mean recoveries of TAP, TA and IS were 86.7–104.7%. The method was successfully applied to a long-term pharmacokinetic study of TAP and TA after 28-day repeated intravenous administration of TAP lipid emulsion injection to beagle dogs.

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