Prednisolone Pharmacokinetics in Severe Asthma

The purpose of the study is to evaluate whether severe asthmatic subjects have abnormal prednisolone absorption, and how this might affect the anti-inflammatory effects of prednisolone. The aims of the study are 1. to compare the effect of high dose prednisolone on clinical and physiological responses 2. to determine the effect of long-term oral prednisolone therapy on corticosteroid responsiveness and prednisolone pharmacokinetics 3. to measure the effect of high dose prednisolone for 14 days on p38 MAPK activity, GR translocation and activation of NF-kB 4. to validate an easier method of measuring corticosteroid insensitivity using whole blood, and a spot prednisolone serum level as a measure of adherence to prednisolone therapy