Almirall’s share price is sliding this morning after the Spanish firm and partner Forest Laboratories presented less-than-impressive late-stage data on aclidinium, their new treatment for chronic obstructive pulmonary disease.

The companies announced results from two global Phase III studies of aclidinium, a novel long-acting inhaled anticholinergic for COPD. In both the ACCLAIM/COPD I&II studies, the drug, taken once-daily, showed a statistically significant difference versus placebo using a standard measure of pulmonary function, FEV1 (the volume of air that is exhaled in the first second). The dosage used was 200mcg.

Aclidinium significantly improved the percentage of patients showing a clinically relevant improvement in health-related quality of life compared with placebo as measured by the St George's Respiratory Questionnaire. However the firm acknowledged that ACCLAIM/COPD II, which involved 1,647 patients from 23 countries, did not reach statistical significance for SGRQ at week 52, but did achieve it at all previous time-points.

Per-Olof Andersson, executive director R&D of Almirall. said the studies “confirm the bronchodilatory effect of aclidinium at the dose tested, although the magnitude was lower than seen in previous studies”. He added that the Barcelona-based firm is “working actively with Forest and members of the ACCLAIM/COPD steering committee to fully understand these findings to determine the best way forward including the extent of the benefit possible from dosing alternatives".

Forest seemed pretty happy with the data. The US firm’s chief executive, Howard Solomon, said that his company “is pleased with the results of these studies and remains committed with Almirall to the development of aclidinium”.

However it seems that investors do not share his enthusiasm and at 10.05 this morning (UK time), Almirall’s shares were down 18.7% to 12.19 euros. Aclidinium would transform the Spanish drugmaker if it receives approval and gets to challenge Boehringer Ingelheim's blockbuster Spiriva (tiotropium), which is marketed by Pfizer, for the number one spot in COPD.