1. Makela MJ, Backer V, Hedegaard M, Larsson K. Adherence to inhaled therapies, health outcomes and costs in patients with asthma and COPD. Respir Med. 2013;107:1481–90.
2. SPIRIVA® HandiHaler® (tiotropium bromide inhalation powder) capsules for respiratory inhalation [prescribing information]. Ridgefield, CT, USA: Boehringer Ingelheim Pharmaceuticals Inc. 2014.
3. Spiriva 18 microgram inhalation powder, hard capsule. SPC. Boehringer Ingelheim Ltd. http://www.medicines.org.uk/emc/medicine/10039/SPC/Spiriva+18microgram+inhalation+powder . Accessed 20 Aug 2015.
4. SPIRIVA® Respimat® (tiotropium bromide) inhalation spray: for oral inhalation [prescribing information]. Ridgefield, CT, USA: Boehringer Ingelheim Pharmaceuticals, Inc. 2015.
5. Spiriva (tiotropium) Respimat 2.5 micrograms, solution for inhalation. SPC. Boehringer Ingelheim Limited. https://www.medicines.org.uk/emc/medicine/20134 . Accessed 20 Aug 2015.