165 Other fields where chronopharmacology is of demonstrated relevance are those of asthma and cardiovascular disorders.166,167 In the field of psychotropic agents or illegal drugs, aside from research on laboratory animals, and research on alcohol,

little is known on circadian changes in pharmacodynamics. In particular, the extent of changes in the concentration/response curve over the course of the day has not been well evaluated in humans. The pharmacology of alcohol shows circadian changes.168 Several studies during the last 50 years have shown that alcohol is absorbed more rapidly, with higher blood levels when taken during the morning, but that it is also eliminated faster.169 #SCR7 mw keyword# Each addicted person has his or her own daily schedule to start the consumption of alcohol 170 Alcohol given during one day to nonaddicted volunteers does not influence the circadian rhythm, nor the concentration of Cortisol, but it increases that of testosterone171 and suppresses the nocturnal Inhibitors,research,lifescience,medical increase of TSH, and decreases the mean concentration of the later hormone.168 Clinical consequences of chronopharmacology There is little information as to whether giving a psychotropic medication once a day Inhibitors,research,lifescience,medical or as a divided dose shows any benefit in terms of efficacy or side effects. It might be with substances that themselves influence the

physiology of biological clocks that chronopharmacology will find its major application. Inhibitors,research,lifescience,medical Benzodiazepines and other sedatives can influence the phase position of circadian rhythms, and lithium, as well as a few antidepressants, might modify the functioning of the SCN.172 However, lithium and most antidepressants and many benzodiazepines have a half -life of elimination that is longer that 12 hours; thus their effects persist throughout the nicthemere. Melatonin has a short half-life and its timing of administration is quite

relevant for its efficacy in SAD treatment.77 The following general clinical and general rules prevail: a stimulating medication should be given Inhibitors,research,lifescience,medical in the morning and not late in the afternoon or in the evening, a medication that is sedative should be given at the time of sleep, and a medication that induces nausea might be better tolerated when given with a meal. Conclusion The time structure of biology is as essential as is its spatial structure, yet the relevance of chronobiology for pathophysiology remains underestimated in internal medicine, neurology, or psychiatry This might be because measuring the rhythms Dipeptidyl peptidase of most biological variables over the long term is complex, because feedback loops and regulations maintain vital phenomena within apparently stable ranges labeled as norms, and finally because our knowledge about the temporal structure of biology remains incomplete. Indeed, the relation between endogenous biological oscillators is far less well established than are mechanisms in other domains of biology, for example endocrine feedback mechanisms.