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

Rationale: 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.

Objectives: 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.

Methods: 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).

Measurements And Main Results: 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.

Conclusion: 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.