Nicotine

General 10: What happens in the kidneys?

The nicotine and its breakdown products (metabolites) arrive at the kidneys’ filter elements, the nephrons.

The nicotine molecules flow with the blood fluid, or plasma, through the filters (1) and become part of the primary urine. The largest part of the primary urine is then returned to the bloodstream, including most of the nicotine molecules that were not yet broken down by the liver (2). All the breakdown products of nicotine will ultimately be eliminated from the body. Only 10 percent of all the nicotine molecules that enter the body are normally excreted into the urine unchanged (3).

When the production or the acid concentration of the urine is high, up to 30 per cent of the nicotine may be excreted unchanged. The large majority of nicotine molecules must still be broken down in the liver before they can leave the body.