Oxycodone acts directly on a number of tissues not related to its analgesic effect. These tissues include the respiratory centre in the brain stem, the cough centre in the medulla, muscles of the pupils, gastrointestinal tract, cardiovascular buy oxycodone online, endocrine system, and immune system.Label Oxycodone's effect on the respiratory centre is dose dependant respiratory depression.Label The action on the cough centre is suppression of the cough reflex.Label Pupils become miopic or decrease in size, peristalsis of the gastrointestinal tract slows, and muscle tone in the colon may increase causing constipation.Label In the cardiovascular system histamine may be released leading to pruritis, red eyes, flushing, sweating, and decreased blood pressure.Label Endocrine effects may include increased prolactin, decreased cortisol, and decreased testosterone.Label It is not yet known if the effects of opioids on the immune system are clinically significant.Label