Chapter 13 Biological Rhythms, Drug Delivery, and Chronotherapeutics Michael H. Smolensky, Ronald A. Siegel, Erhard Haus, Ramon Hermida, and Francesco Portaluppi Abstract Biological processes are highly structured in time as endogenously derived rhythms of short, intermediate, and long periods, with the circadian (24 h) time structure most studied. Staging of key physiological and biochemical circadian rhythms gives rise to 24-h patterns in the exacerbation of chronic medical conditions, including arthritis, asthma, ulcer, and hypertension, plus manifestation of acute severe morbid and mortal events, such as myocardial infarction, stroke, M.H. Smolensky (*) Department Biomedical Engineering, The University of Texas at Austin, 1 University Station, Mail Code CO800, Austin, TX 78712-0238, USA e-mail: Michael.H.Smolensky@uth.tmc.edu; msmolensky@austin.rr.com R.A. Siegel Departments of Pharmaceutics and Biomedical Engineering, University of Minnesota, Minneapolis, MN 55419, USA Department of Pharmaceutics WDH 9-177, University of Minnesota, 308 Harvard St. S.E., Minneapolis, MN 55455, USA e-mail: siege017@umn.edu E. Haus Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA HealthPartners Medical Group, Regions Hospital, St. Paul, MN, USA e-mail: Erhard.X.Haus@Healthpartners.com R. Hermida Bioengineering & Chronobiology Laboratories, University of Vigo, Campus Universitario, Vigo, Spain e-mail: Rhermida@uvigo.es F. Portaluppi Department of Clinical and Experimental Medicine, Hypertension Center, University Hospital S. Anna, University of Ferrara, Ferrara, Italy e-mail: prf@unife.it J. Siepmann et al. (eds.), Fundamentals and Applications of Controlled Release Drug Delivery, Advances in Delivery Science and Technology, DOI 10.1007/978-1-4614-0881-9_13, # Controlled Release Society 2012 359