Effect of diltiazem on methacholine-induced bronchoconstriction in extrinsic asthmatics

The protective effect of the calcium antagonist diltiazem on methacholine-induced bronchoconstriction was investigated in 19 extrinsic asthmatics. A double-blind cross-over design was used (diltiazem vs. placebo, administered orally for 1 week). We found no significant difference between the two treatment regimens when expressed as the provocation dose of methacholine causing a 20% drop in forced expired volume in 1 s (PD20 FEV1). Some individual patients might nevertheless gain some benefit from diltiazem as an additional treatment in difficult-to-manage asthma.