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PHARMACOLOGY OF DEXMEDETOMIDINE Dexmedetomidine HCl, an imidazole compound is the pharmacologically active s-enantiomer of medetomidine, a veterinary anaesthetic agent. It is described chemically as (+)-4-(s)[2 3 –(dimethylphenyl) ethyl]-11 H-imidazole monohyrochloride. Its empirical formula is C13H16N2HCl and its molecular weight is 236.7(57). Figure 4 : Structure of Dexmedetomidine PHYSIOCHEMICAL PROPERTIES A white or almost white powder that is freely soluble in water with Pka of 7.1.Partition coefficient in octanol: water at pH 7.4 is 2.89. Preservative free dexmedetomidine is available in 1ml and 2 ml ampoule as Dexmedetomidine Hydrochloride for intravenous use (Alphadex, Fusion health care 100 μg/ml). It can also be used for intrathecal and epidural anaesthesia. MECHANISM OF ACTION OF DEXMEDETOMIDINE Dexmedetomidine is the dextro enantiomer of medetomidine, the methylated derivative of etomidine, its specificity for the alpha-2 receptor is 8times that of clonidine, with an alpha-2/alpha-1 binding affinity ratio of 1620:1 & its effects are dose dependently reversed by…show more content…
Alpha-2 adrenoceptors are found in CNS in highest densities in the locus ceruleus, the predominant noradrenergic nuclei of the brainstem and an important modulator of vigilance. Presynaptic activation of alpha-2A adrenoceptor in the locus ceruleus inhibits the release of nor-epinephrine & results in the sedative and hypnotic effects(62). In addition, the locus ceruleus is the site of origin for the descending medullospinal nor adrenergic pathway, known to be an important modulator of nociceptive neurotransmission. Stimulation of alpha-2 adrenoceptors in this area terminates the propagation of pain signals leading to analgesia. Postsynaptic activation of alpha-2 receptors in the CNS results in decrease in sympathetic activity leading to hypotension &

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