Development and validation of a sensitive LC-MS/MS method for determination of betamethasone in human plasma. Application to a pharmacokinetic study of healthy Mexican subjects

Background: Synthetic glucocorticoids like Betamethasone (BE) are used in the treatment of inflammatory diseases due to its effective and potent effect. BE is available in three different esters: Dipropionate (BD), sodium phosphate (BP), and acetate (BA). BD/BP combined in suspension has anti-inflammatory, anti-allergic, and anti-rheumatic effects. The aim of this study was to describe the bioavailability of a single-dose of the injectable formulation of BP/BD in healthy Mexican subjects. Methods: This was a randomized, open-label, longitudinal, not therapeutic, single-dose trial of an intramuscular administration of BD/BP (5 mg/2 mg), in healthy Mexican subjects under fasting condition. Twenty-six healthy Mexicans volunteers of both genders who were between the ages of 18 and 45 were enrolled in the study. Results: From non-compartmental estimation of data, it was observed that the BE highest mean concentration was 15.70 ± 3.93 ng/mL reaching it in 2.83 ± 1.35 h. The values of elimination half-life were 10.89 ± 2.02 h. No clinically significant adverse effects were presented during the study. Conclusion: The reported PK parameters for BE suggest that the BD/BP suspension has a similar release velocity in Mexican healthy subjects compared with previous studies.