The efficacy and tolerability of salmeterol, 50 micrograms b.i.d. was compared for three months with salbutamol, 200 micrograms q.i.d., administered from metered-dose inhaler. For the following nine months, safety and clinic lung function was monitored on salmeterol, 50 micrograms b.i.d., compared with salbutamol, 200 micrograms b.i.d. This comparison was made in a multicentre, double-blind, pa...