The protective effect of methylprednisolone on carbachol-induced bronchospasm

We studied the effect of acute treatment with methylprednisolone in 12 asthmatics not dependent on steroids. Carbachol challenge was performed according to a standardized method. Baseline measurements of forced expiratory volume in one second (FEV1), specific airway conductance (SGaw), the provocative dose of carbachol for a 20% decrease in FEV1 (PD20), and that for a 35% decrease in SGaw (PD35) were established. Thereafter, patients returned for retesting at 2, 4, and 6 wk. Prior to each visit, the patients received 1 of 3 treatments: placebo, low-dose (32 mg) methylprednisolone, or high-dose (128 mg) methylprednisolone given orally and distributed in a randomized double-blind fashion. Blood levels confirmed compliance in all subjects. All subjects remained stable throughout the study, with intrasubject FEV1 values agreeing within 5% at the start of each session. The pairwise differences for low-dose methylprednisolone versus placebo were significantly different for both PD20 (p = 0.0004) and PD35 (p = 0.0068). The pairwise differences for high-dose methylprednisolone versus placebo were also significantly different for PD20 (p = 0.04) and PD35 (p = 0.0034). Blocked comparisons of the 2 different methylprednisolone doses were not significantly different. We conclude that methylprednisolone has a protective effect on carbachol-induced bronchospasm, and that this effect is not dose-related at the two doses studied.