Final answer:
Short-acting barbiturates are metabolized mainly in the liver, which is involved in breaking down various substances through drug metabolism before metabolites are excreted by the kidneys.
Step-by-step explanation:
Short-acting barbiturates are primarily metabolized in the liver. The liver is deeply involved in the breakdown or modification of various substances, including drugs, through a process known as drug metabolism. While the metabolites produced by this process are not directly removed from the body by the liver, the breakdown products of various substances like ethanol, nicotine, and drugs such as barbiturates are processed into less active or inactive forms by hepatic enzymes before being excreted by other routes, predominantly the kidneys.
Specifically, the involvement of the liver in drug metabolism often includes the actions of enzyme systems like Catechol-O-Methyl-Transferase (COMT) and Mono-Amine Oxidase (MAO), contributing to the drug's detoxification and preparation for excretion. After modification, compounds like the metabolites of barbiturates are usually soluble enough to be excreted via the kidneys in urine, ultimately leaving the body. Therefore, the correct answer to the question of where short-acting barbiturates are metabolized is the liver (Option A).