Anticholinergic inhalers contain a chemical that prevents the activation of acetylcholine receptors. This receptor is found on many different kinds of cells, including the contracted smooth muscles cells found in the constricted airways of patients suffering from asthma attacks and COPD. By blocking the receptors, the smooth muscles loses the signal that tells it to continue to contract, preventing the airways from constricting more, essentially stopping the progression of the attack. This limits feelings of breathlessness in patients with asthma and COPD. Anticholinergics also reduces the production of mucus. Excessive mucus worsens the effect of airway constriction by further clogging them.
There are essentially two anticholinergics inhalers on the market, ipratropium, which is marketed as Atrovent, and tiotropium, which is marketed as Spiriva. They differ in their duration of action. Ipratropium is short acting. It works within 15 minutes, but only lasts for 4 to 6 hours. Spiriva, on the other hand, lasts for the entire day. Neither can be used as a rescue inhaler by itself, because rather than reversing the constriction of the airways, anticholinergics only prevent it from getting worse. Ipratropium is used to enhance the effects of albuterol. Tiotropium is used for the long-term prevention of asthma attacks and reduction of COPD symptoms.
Though only a limited amount of inhaled anticholinergics enter the bloodstream, they can sometimes cause vision and urinary problems in certain patients predisposed to it. Inform your physician if you notice blurry vision or have trouble urinating after taking these medications.