Many of the drugs leave the market due to their adverse effects than their therapeutic effects. If the pharmacology of the drug and its adverse effect is Circadian Time (CT) dependent, it can be modulated by altering the time of administration of drugs. Chronopharmacology describes the effect of drugs in terms of time of administration. Its main objective is chronotherapy (time based treatment). Here the psychopharmacological drug such as Diazepam, Chlorpromazine and Phenobarbitone undergoes circadian investigation by using Latin square design. Male albino wistar rats were selected, divided into four groups, each group consist of six animals and subjected for investigation. Animals are acclimatized for 12 h L/D cycle in laboratory condition and animals were given access to feed and water ad libitum. Rats were treated with Diazepam (4 mg/kg b.w, orally), Chlorpromazine (3 mg/kg b.w, orally) and Phenobarbitone (16 mg/kg b.w, orally) at CT 0200, CT 0800, CT 1400 and CT 2000 respectively. Anxiolytic effect, skeletal muscle relaxant effect and locomotor effect were recorded by using Actophotometer, Rota rod apparatus, Elevated plus maze and Mirror chamber apparatus at different circadian time mentioned above. The effect of drug was determined by using chronogram. Based on the observation it was concluded that the rhythmic activity of rats was not influencing the pharmacology of Diazepam, Phenobarbitone but circadian pattern influences the activity of Chlorpromazine.
