Sustained release theophylline and nocturnal asthma [antikvár]

Circadian rhythms in chronic obstructive pulmonary disease M. H. Smolensky1'3 and J. P. McGovern14 'School of Public Health and Graduate School of Biomedical Sciences and 2School ofMedicine, University of Texas Health Science Center at Houston, and3 McGovern Allergy Clinic and4 Baylor College ofMedicine, Houston, TX, USA Introduction For many years, the search to explain the exacerbation of respiratory distress during the nighttime in patients with chronic obstructive pulmonary disease (COPD) was directed at day-night differences in the external environment. Based exclusively on homeostatic considerations, earlier epidemiologic investigations assumed a priori that 24-hour cycles in the patient's microenvironment alone were the cause of the nocturnal worsening of symptoms. Thus, the literature abounds with subjective allegations that nocturnal distress in COPD is the result of a cooler nighttime temperature, intimate contact with offending antigens in the bedding, accumulation of psychological and physical stresses during the day and supine posture affecting pulmonary function, to mention the more common ones. However, chronobiologic (biological rhythm) studies on COPD patients have provided a different and broader perspective of COPD; the epidemiology of the nocturnal exacerbation of asthma and other COPD emphasizes the primary significance of endogenous circadian (approximately 24-hour) rhythms in pertinent biological functions in relationship to the quality of the external environment, which alsó changes cyclically during each 24-hour period. Circadian rhythms of respiratory distress Although physicians have long known about the nocturnal worsening of COPD symptoms, surprisingly few scientific investigations have objectively evaluated the magnitude of the day-night difference in their occurrence. Figure