Management of the Drug Abusing Patient in the ICU

Abstract

The dopaminergic mesolimbic system originates in the ventral tegmenial nucleus with a projection to the nucleus accumbens and plays a critical role in mediating effects of opioid. The opioid receptors include mu, kappa, sigma, delta, and epsilon. Opioid-induced activation of mu and sigma receptors increases the activity of the dopaminergic mesolimbic system releasing dopamine into the nucleus accumbens, which produces feelings of euphoria and well-being. Stimulation of the kappa receptors decreases aclivity of the mesolimbic system, resulting in dysphoria. Enzymatic inhibition at the mu receptors in the locus ceruleus leads to a decrease in norepinephrine production. However, chronic use of opioids leads to increased enzymatic activity at the mu receptors, thereby resulting in normal or higher levels of norepinephrine. Following opioid deprivation, there is loss of inhibitory effect on enzyme activity. The excess norepinephrine released leads to symptoms such as muscle cramps, diarrhea, anxiety, and tremors. (PsycInfo Database Record (c) 2020 APA, all rights reserved)