Pharmacokinetics of prednisone and prednisolone in bullous pemphigoid patients.

The purpose of this prospective study was to attempt to evaluate a possible relationship between corticosteroids pharmacokinetics parameters and clinical efficacy in bullous pemphigoid (BP) patients. Sixteen BP patients took part in the study. Prednisone (Cortancyl, Laboratoire Roussel) was given orally (1 mg/kg/day) in a single morning dose. Eleven blood samples were collected over 24 h for the pharmacokinetic studies on day 1 (first day of treatment) and on day Y (after the clinical evaluation). Efficacy was evaluated as the number of new skin blisters on day 1 and on day X which was either the day of cure, i.e. no blisters (responders), or the day of treatment failure, i.e. persistence of blisters (non-responders). Prednisolone (PO) was assayed using high-performance liquid chromatography (HPLC). Areas under the plasma concentration time curves (AUC) and plasma half-lives were estimated using a model independent approach. In responder patients, PO AUC values were 6,225.5 +/- 575.5 ngh/ml, range 3,933-9,080.5 on day 1 and 5,687 +/- 535 ngh/ml, range 4,513.5-9,828.5 on day Y. There was a significant correlation (0.87) between the number of skin blisters on day 1 and the time required for their resolution. The pharmacokinetics and clinical data suggest that a "therapeutic" AUC value was necessary to achieve clinical efficacy and that the duration of treatment depended on the number of blisters on day 1.(ABSTRACT TRUNCATED AT 250 WORDS)