The cocaine and its metabolites arrive at the filter elements of the kidneys, the nephrons.
They 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 blood (2). Most of the cocaine breakdown products stay behind in the primary urine to be discharged from the body.
About half of the cocaine in the blood has been removed within 90 minutes. The kidneys have more trouble processing the cocaethylene that is formed when cocaine and alcohol are taken in combination. Cocaethylene remains in the blood 3 times longer than cocaine. The primary urine that is not returned to the blood becomes the final urine (3) and it will leave the body through the bladder.