Which opioid has a ceiling effect of accumulation of Carbon Dioxide?
Due to the unique pharmacology (partial mu-agonist, as discussed in Question 5), buprenorphine provides analgesia at therapeutic doses but also has a suggested “ceiling effect” on respiratory depression. As the medication dose increases, the activity that buprenorphine exhibits as a partial agonist plateaus regardless of subsequent increases. Opioids block the carbon dioxide feedback loop that is used to stimulate the brainstem to increase respiratory rate. The higher the dose, the more effect an opioid has on the feedback loop and the greater the risk of respiratory depression. Buprenorphine, due to its “ceiling effect” at the opioid receptor, has a much lower likelihood of respiratory depression. The risk is, however, still elevated in the presence of benzodiazepines and other sedating substances.