Circadian rhythm

Aim of the present work was to formulate and evaluate an oral, time controlled drug delivery system to achieve timed release of Montelukast sodium, for the treatment of nocturnal asthma. An asthmatic attack mainly takes place early in the morning. Time controlled delivery system is capable of delivering drug when and where it is required most. Time-delayed tablets, designed to release drug after a predictable lag time, are intended for oral chronotherapy. A time dependant pulsed release system consisting of a core surrounded by coat layer of different ratios of swellable erodible hydrophilic layer HPMC K100M and rupturable hydrophobic layer Eudragit L 100 and Eudragit S 100 were prepared. These pulsatile tablets were evaluated for the drug content, thickness and in-vitro release profile, etc. and  two optimized formulation were selected and subjected to further studies. .

Chronotherapeutic drug delivery system is useful in the treatment of disease, in which drug availability is timed to match rhythm of disease, in order to optimize therapeutic effect and minimize side effects. There is an impact of circadian rhythms in the symptoms of certain diseases like asthma, arthritis, depression, ulcer, allergic rhinitis, sleep disorders etc. The human body follows the solar/ lunar adaptations known as biological clock. The role of circadian rhythms in the mechanisms of disease and the pharmacokinetics and pharmacodynamics of medications constitutes a challenge to drug-discovery and drug-delivery scientists. We must strive to develop intelligent drug-delivery systems that can affect a target cell or organ system at that circadian time when it is possible to optimize desired therapeutic outcomes and minimize or avert adverse effects. The present article covers findings about the effects of biorhythms on various disorders, and their implications for drug therapy are discussed. Here we also reviewed the design of novel chronopharmaceutical drug delivery systems that might be able to release the therapeutic agents at predetermined intervals. Keywords:Chronotherapy, Circadian rhythm, Chronopharmaceutics, Chronopharmacokinetics.