Bronchodilatory effect of inhaled zardaverine, a phosphodiesterase III and IV inhibitor, in patients with asthma.

Zardaverine is a newly developed selective phosphodiesterase III and IV inhibitor. This study investigates the bronchodilatory properties of zardaverine, administered by inhalation. Twelve patients with reversible bronchial obstruction (increase in forced expiratory volume in one second (change FEV1 % predicted) at least 15% after 200 micrograms salbutamol, median age 31 yrs, range 21-54 years) entered the double-blind, crossover study. Four puffs of either zardaverine (total dose 6 mg) or placebo were inhaled at 15 min intervals. Pulmonary function (specific airway conductance (sGaw) and FEV1 was measured by body plethysmography at regular intervals (5 and 12 min after each puff and, in addition, 30, 60, 120, 180 and 240 min after the last puff). Compared to placebo, sGaw and FEV1 increased significantly during the first hour of repeated inhalations, but not during the entire observation period of almost 5 h. The maximum mean difference between zardaverine and placebo for FEV1 was 0.3 l or 12% and occurred approximately 1 h after inhalation of the first puff. In seven patients FEV1 increased by > 15%. The duration of action varied considerably between patients. Three patients complained of side-effects (headache, drowsiness, vertigo, nausea), and one of these dropped out of the study due to vomiting. We conclude that inhalational administration of zardaverine has a modest and short-lasting bronchodilating activity.