The present invention relates to a novel process for the preparation of anticholinergic agents/drugs, such as umeclidinium bromide, tiotropium bromide, glycopyrronium bromide, aclidinium bromide, ipratropium bromide (V) in continuous flow mode in the presence of one or more polar protic solvents. The anticholinergic drugs are in a form suitable for use in inhalation in the treatment of respiratory diseases such as asthma or chronic obstructive pulmonary disease (COPD).