Abstract

THE CLOCK WHICH TIMES US- CHRONOBIOLOGY, CHRONOPHARMACOLOGY AND CHRONOTHERAPEUTICS – NEXT FRONTIER IN OPTIMIZING DRUG THERAPY

Nasreen Sulthana*, Ayesha Sultana, B. Bindu Madhavi

ABSTRACT

Chronobiology is the branch of science which examines periodic phenomenon in living organisms and their adaptation to biological rhythm. These biological rhythms can be yearly, monthly, daily or more frequent. Daily (24hr) rhythms are called as circadian rhythms. Chronopharmacology is one of the disciplines which take into account the influence of time. It is concerned with the effects of drug upon the timing of biological events and rhythms and the relation of biological timing and endogenous periodicities to the effect of drugs. It further deals with chronotherapeutics, chronokinetics, and chronotoxicity. The circadian rhythms in mammals are maintained and regulated by the master clock in brain called as Supra chiasmatic nucleus (SCN) present in hypothalamus. Circadian rhythms deals with the cyclic changes occurring in day and night which depends on absence and presence of light. When the light falls on the retina, the light sensitive ganglion cells act as receptors and sends signals to SCN through retinohypothalamic tracts. SCN either directly by influencing pineal gland which releases melatonin or indirectly by influencing autonomic nervous system regulates different physiological activities. Biological rhythms are observed in different physiological organ systems like urinary, gastrointestinal tract, hepatic system, cardiovascular system and endocrine system. Circadian rhythms are also exhibited by many diseases. Some drugs show difference in absorption (A), distribution (D), metabolism (M) and excretion (E) in relation to time. The study which deals with the temporary changes in ADME and takes into account the influence of time of administration on these different processes is called as chronopharmacokinetics or chronokinetics. The present review focuses on the chronobiology, chronopharmacology, chronokinetics of different drugs and their applications in treating different diseases i.e chronotherapeutics. It also focuses on different techniques involved in formulation of drugs undergoing chronopharmacokinetics.

Keywords: circadian rhythms, suprachiasmatic nucleus, chronopharmacology, chronopharmacokinetics, chronotherapeutics, pulsatile drug delivery system.