Acute Asthma Rescue Therapy Study Part 2

1. Two week reliability check - Measure PEF pre bronchodilator BD. i) Subject excluded from further participation if electronic PEF diary reveals non-compliance (<80% of expected readings performed) or falsified entries (hand written entires not corresponding to electronic diary recorded entries). ii) if after 2 weeks inclusion criteria not met but satisfactory compliance, then continue for a further fortnight. 2. Commence study. Subject receives treatment pack (first of 2 in concealed and randomised order). Treatment packs consist of: a) Maintenance ICS. Exacerbation fluticasone (either real drug or placebo marked as extra preventer in case of exacerbation); OCS tablets (either real or placebo dexamethasone); and Rescue tablets (real prednisolone). Subjects may continue short acting reliever of their choice. 3. Routine management of asthma. During this period symptoms, medication use and PEF to be recorded on wakening three time a week. 4. In the event of PEF deterioration consistent with trial definition of exacerbation, the subject commences their treatment pack after contacting one of the investigators. During the treatment period subjects will be requested to record symptoms, medication use and PEF upon awakening and in the evening prior to taking routine and trial medications. 5. Therapy will consist of - bronchodilator as required + usual ICS + real high dose ICS + placebo OCS OR - bronchodilator as required + usual ICS + placebo high dose ICS + real OCS 6. Subjects will continue on the treatment pack for 7 days. Dexamethasone will be given in a constant non-reducing course of approx. 0.1mg/kg day to a maximum of 12 mg as a once daily dose for 7 days. This equates to a dose of 0.6mg/kg of prednisolone and is the recommended dose from a dose finding study by Webb. Obese subjects (BMI greater than 30) will have their dose adjusted to the weight that would achieve a BMI of 30 (borderline obesity) to avoid excessive dosing due to obesity. 7. Subjects classified as treatment failures or whose PEF falls initially to less than 60% of best will be treated with the rescue (real prednisolone) and/or according to the judgement of the relevant trial respiratory physician. 8. Following either the successfully completed 7 day treatment period or rescue therapy the subject will have a four week wash-out period to avoid carry over effect to the next treatment arm. Subjects will be requested to record symptoms and PEF each morning during the washout period to accurately ascertain timing of late relapses/recurrences. During this period subjects will return to taking the dose of fluticasone used prior to the last back titration before the exacerbation if a back titration was performed within 4 weeks, or the same dose as at exacerbation if the last back titration occurred more than 4 weeks prior to the exacerbation. 9. Following the one month washout period, subjects will then collect the next treatment pack and re-enter maintenance phase. Each subject will be followed for 2 exacerbations.