1. Tougas TP, Christopher D, Mitchell JP, Strickland H, Wyka B, Van Oort M, et al. Improved quality control metrics for cascade impaction measurements of orally inhaled drug products (OIPs). AAPS PharmSciTech. 2009;10(4):1276–85.
2. United States Food and Drug Administration. Center for Drug Evaluation and Research (CDER): draft guidance for industry metered dose inhaler (MDI) and dry powder inhaler (DPI) drug products chemistry, manufacturing, and controls documentation. 1998. http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM070573.pdf . Accessed 10 Oct 2015.
3. Health Canada: Pharmaceutical quality of inhalation and nasal products. 2006. http://www.hc-sc.gc.ca/dhp-mps/prodpharma/applic-demande/guide-ld/chem/inhalationnas_e.html . Accessed 10 Oct 2015.
4. European Medicines Agency: 2006 EMEA/CHMP/QWP/49313/2005 Corr. http://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2009/09/WC500003568.pdf . Accessed 10 Oct 2015.
5. US Pharmacopeial Convention: United States Pharmacopeia 38/National Formulary 33, Chapter <601> Aerosols, nasal sprays, metered-dose inhalers, and dry powder inhalers. Rockville, MD, 2015.