“In four exploratory studies, inhaled RPL554 is an effective and well tolerated bronchodilator, bronchoprotector and anti-inflammatory drug, and further studies will establish the full potential of this new drug for the treatment of patients with COPD or asthma,” Lui G. Franciosi, PhD, from Verona Pharma in London, and colleagues reported in Lancet Respiratory Medicine.
They examined the safety and efficacy of an inhaled dual phosphodiesterases 3 and 4 inhibitor, RPL554, for the treatment of mild-to-moderate asthma or COPD.
Nebulized RPL554 produced bronchodilation in patients with mild-to-moderate COPD, with a 17.2% increase in forced expiratory volume in one second compared with placebo, the researchers found. In patients with airway disease, RPL554 produced rapid bronchodilation and peak effects similar to those obtained with inhaled β2 agonists, which was maintained in asthma patients with repeated dosing.
In asthma patients, the drug boosted that measure of bronchodilation by 14% compared with placebo (P<0.0001), with effects maintained over repeat dosing, the researchers found.
In healthy volunteers, RPL554 missed the primary endpoint of reduction in lipopolysaccharide-induced recruitment of sputum neutrophils (80.3% vs. 84.2%, P=0.15), but did cut down on immune cells in sputum overall (P=0.001 to P=0.044).
Overall, RPL554 was well tolerated with generally mild adverse effects of equal frequency compared with placebo across the four studies. The most frequently reported adverse events were headache, irritation of the larynx and dizziness in one study. Headache, nasal congestion, rhinorrhea, cough and application site irritation were the most common in another, although they were reported in about equal frequency as with placebo.
The studies had several limitations — some participants were not blinded to treatment, only a limited number of dosing schedules were studied and the studies were of short duration.