resulted in statistically significant increases in TDI score
that exceeded the 1-point difference considered clinically
important.
22 Reduction in hyperinflation with NVA237
treatment, demonstrated by an increase in IC on Days 1 and
21 in the current study, is an important factor that likely
contributed to the improvement in dyspnea and exercise
capacity. Exercise-limiting leg discomfort has also been frequently
reported in COPD patients.29,33 NVA237 significantly
improved the Borg CR10 score on Day 21 versus placebo
administration.
Notably, leg discomfort tended to be lower in
NVA237- versus placebo-treated patients on Day 1. From a
mechanistic perspective, better oxygenation of the leg muscles
is expected to lead to some improvement in muscular function.
However, this finding has not been consistently found in other
trials with bronchodilators. For example, treatment with the
short acting bronchodilator ipratropium were not associated
with a significant improvement in leg discomfort score.34 In
the present study, a significant improvement was observed at
isotime during exercise, whereas no differences were observed
at peak exercise. Given the fact, that the exercise test used is
symptom-limited, this finding at peak is not surprising since it
reflects the cessation of exercise by patients due to intolerable
dyspnea or leg discomfort. In contrast, the observed differences
in the level of leg discomfort at isotime may have been
the result of improved ventilation with NVA237, leading to
improved oxygenation and peripheral muscle function during
a given workload, and flattening of the slope of leg discomfort
as a function of endurance time.
Importantly, consistency between improved lung function
and body plethysmographic measures were observed as well
as improved dyspnea measures at rest and exercise in this
study. This may underscore the relevance of bronchodilatory
therapy for improving exercise capacity.
In terms of safety, NVA237 50 μg once daily was
well-tolerated and showed an acceptable safety profile.
Safety results are consistent with those from previous
studies.15,17–19
Limitations of this study include short time period and
that it was not coupled with another intervention, such as
rehabilitation, to augment the response to therapy. Both a
longer duration of the trial beyond 3 weeks of treatment
and combining therapy with a pulmonary rehabilitation
program may lead to further clinically meaningful effects.
Additionally,
cycle ergometry is more artificial than other
methods such as a walking test; some patients may not be
used to this type of exercise. It has been shown that stopping
exercise due to leg discomfort occurs more frequently
when cycling than during walking tests.35 Thus, the effects
of treatment on cycling endurance may be more difficult to
translate into changes for COPD patients’ everyday activities
than a walking test. Nevertheless, cycling ergometry
has been shown to be reliable and safe.36 Furthermore, cycle
ergometry offers a relatively easy and standardized method
for measuring dynamic IC, in contrast to a walking test,
which requires portable systems for measuring respiratory
parameters throughout the exercise, thereby making obtaining
reliable measures of IC more challenging.37
In conclusion, once-daily treatment with NVA237 results
in significant improvement in exercise tolerance beginning
with the first dose. Additionally, NVA237 reduces lung
hyperinflation and offers clinically meaningful improvements
in trough FEV1 and breathlessness