Acute and short-term effect of an extra dose of formoterol in COPD patients

Formoterol action may decrease progressively after its inhalation. It is unknown if this decrease of bronchodilation following formoterol use could be associated with worsening hyperinflation.

To investigate whether the use of an extra daily dose of formoterol could promote a greater reduction in lung hyperinflation and a greater improvement in inspiratory capacity (IC) compared to usual doses.

56 hyperinflated COPD patients were divided into two groups: F2 and F3. Basal evaluation was carried out after 5 days of formoterol washout. In order to evaluate the acute effect, spirometry and body plethysmography were performed 8 h after the first formoterol dose in both groups and repeated 1 h after an additional formoterol dose (F3) or placebo (F2). The short-term effect was evaluated by measuring the resting lung function after a 14-day period of formoterol t.i.d. (F3) or formoterol b.i.d. + placebo (F2).

A second formoterol dose inhaled 8 h after the previous dose promoted additional improvements in lung function, as demonstrated by higher IC (118 ± 140 mL, p < 0.001) and lower functional residual capacity (FRC) (-383 ± 367 mL, p < 0.001). On day 15, the mean differences from baseline regarding all lung function variables were similar between the groups.

An extra daily dose of formoterol inhaled 8 h after a previous dose could result in an acute additional peak of bronchodilation. However, short-term formoterol t.i.d. showed no advantages over formoterol b.i.d. concerning reduction of hyperinflation in resting lung function.