What is the primary purpose of probenecid in conjunction with penicillin?

The primary purpose of probenecid when used in conjunction with penicillin is to enhance the absorption of the antibiotic, particularly in the bloodstream. Probenecid acts by inhibiting the renal tubular secretion of penicillin, which results in increased serum concentrations of the antibiotic. This means that probenecid prolongs the half-life of penicillin, allowing it to remain in the body longer and maintain its effectiveness against bacteria. This combination is particularly useful in treating severe infections, where maintaining higher levels of penicillin over a longer period can lead to better clinical outcomes.

To provide additional clarity, while probenecid is not used primarily to increase the effectiveness of antibiotics in a general sense or to treat resistant infections, its foremost role is to ensure increased levels of penicillin are sustained in the body.