Probenecid

Probenecid is a uricosuric drug, primarily used in treating gout or hyperuricemia, that increases uric acid removal in the urine. One of its trade names is 'Benuryl.'

Probenecid also decreases the renal excretion of some drugs.

In one study, probenecid was shown to more than double a patient's exposure to oseltamivir (trade name Tamiflu), an antiviral drug used to combat influenza. This is significant because nations are currently stockpiling oseltamivir in anticipation of an influenza pandemic, and there could be supply shortages. During World War II, probenecid was used to extend limited supplies of penicillin, and is still currently used to increase antibiotic concentrations in serious infections. It has also found use as a masking agent by athletes attempting to get away with using performance enhancing drugs.

In the kidneys it is filtered at the glomerulus, secreted in the proximal tubule and reabsorbed in the distal tubule.

Probenecid's exact mechanism of action in the kidneys' nephrons is unknown. (I wish to question this statement. The text Human Physiology by Dee Unglaub Silverthorn explains that gout is caused by elevated levels of uric acid in the plasma, and that the kidney's organic anion transporter (OAT) reclaims uric acid from the urine and returns it to the plasma. If the organic acid probenecid is administered to a patient, the OAT binds to probenecid instead of to uric acid, preventing the reabsorption of uric acid. As a result, more uric acid leaves the body in the urine, lowering the uric acid concentration in the plasma. This is an example of the way in which competition between substrates transported across cell membranes has been put to use in medicine.)

Probenecid reduces the reabsorption of uric acid.