Persons who abuse small organic molecule drugs such as opioids take them by a variety of routes of administration, but mainly intravenous, oral and inhalation. Depending on the drug or drug cocktail taken, such people run the risk of developing severe respiratory depression (which can be fatal) through effects in the central nervous system.
i. Explain how the parent drug reaches the brain from each route of administration, i.e. intravenous, oral, inhalation (15 pts)
ii. Explain why it is usually necessary to take a much greater dose through the oral route than either intravenous or inhalation routes, to reach a toxic dose in the brain. (10 pts)