A calcium antagonist, nifedipine, modifies exercise-induced asthma

Area of Science:

• Pharmacology
• Respiratory Medicine
• Immunology

Background:

• Exercise-induced bronchoconstriction (EIB) is a common asthma symptom.
• Nifedipine, a calcium channel blocker, is known to affect smooth muscle and secretory cells.

Purpose of the Study:

• To investigate the effect of sublingual nifedipine on exercise-induced bronchoconstriction in extrinsic asthmatic subjects.
• To explore nifedipine's impact on mast cell mediator release and bronchial smooth muscle contractility.

Main Methods:

• Double-blind, randomized, placebo-controlled study in eight extrinsic asthmatic subjects.
• Treadmill exercise tests performed 30 minutes after 20 mg sublingual nifedipine or placebo.
• Measurements included peak expiratory flow, plasma histamine levels, and histamine challenge dose.

Main Results:

• Nifedipine significantly reduced the maximum fall in peak expiratory flow post-exercise compared to placebo (36.0% vs 56.5%).
• Nifedipine prevented the exercise-induced rise in plasma histamine, suggesting inhibition of mast cell mediator release.
• Nifedipine increased the dose of inhaled histamine required to cause bronchoconstriction, indicating a mild inhibitory effect on bronchial smooth muscle.

Conclusions:

• Sublingual nifedipine effectively attenuates exercise-induced bronchoconstriction in extrinsic asthmatics.
• Nifedipine appears to work by inhibiting mast cell mediator release and, to a lesser extent, reducing bronchial smooth muscle responsiveness.
• These findings suggest nifedipine may be a viable option for managing asthma symptoms related to exercise.