142PHARMACOLOGICAL EFFECTS OF DEXMEDETOMIDINE ON HUMAN PUPILLARY REFLEXES UNDER GENERAL ANAESTHESIA: IMPLICATIONS FOR CLINICAL MONITORING AND ANESTHESIA MANAGEMENTThis is an examination of the properties of the alpha2-adrenoceptor agonist dexmedetomidine about human pupillary responses and opioid-augmented general anesthesia. Our hypothesis was that dexmedetomidine would induce miosis because of the inhibitory effect it exhibits on the pupilloconstrictor nucleus, after the depressant effect of anaesthesia on the locus coeruleus. Also, we assumed that there should be no significant effect of the drug on the strength of the light reflex as there is removal of the emotional stimuli by the anaesthesia. A total of eight healthy volunteers who were selected (3 men, 5 women) were enrolled, and their)(advanced)IR pupillomet C Radhikary was used to quantify their pupillary responses. To obtain a target of 0.6 ng/ml of plasma dexmedetomidine was infused intravenously. We found that the width of pupil was not altered by dexmedetomidine, but its response to the light (P < 0.05) was substantially increased versus non-painful stimulus (P < 0.05) having less reflex dilation in a noxious stimulus. The delay in onset reflex dilation also showed the drug to exert its effect on the central mechanism as well. These results indicate that dexmedetomidine augments light reflex through central mechanisms which may occur through the hypothalamus and are not congruent with animal model mechanisms. The study offers valuable observations concerning the pharmacological implications of the application of 2- adrenoceptor agonists on the human pupil under anaesthesia, and about the monitoring of the soundness of the midbrain and cranial nerves in the legitimate illRiya@gmail.comResearch622016Dexmedetomidine, Pupillary Reflex, Light Reflex, Anaesthesia, ?2-Adrenoceptor AgonistRiya Zullah M S,RadhikaCAssistant Professor, Deportment of Pharmacology, Prathima Relief Institute of Medical Sciences, Nagunur, Karimnagar- 505417, India,Assistant Professor, Department of Pharmacology, Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry 605502, India