What is the purpose of administering Probenecid with penicillin?

The purpose of administering Probenecid with penicillin is to block the excretion of penicillin. Probenecid works by inhibiting renal tubular transport, which reduces the rate at which penicillin is excreted by the kidneys. This leads to increased levels of penicillin in the bloodstream, allowing for prolonged therapeutic effects and extended duration of action. By preventing the rapid elimination of the antibiotic, Probenecid helps maintain effective levels of penicillin in the body, which can be beneficial in treating infections where sustained drug concentration is crucial for effectiveness.

The other options do not accurately describe the interaction between Probenecid and penicillin. For instance, while enhancing absorption and reducing dosage could be potential goals in some contexts, they do not directly apply to the pharmacological role of Probenecid in this case. Additionally, alleviating allergic reactions is not a function of Probenecid; rather, managing allergic reactions would typically involve different medications or interventions. Therefore, blocking excretion is the primary and correct reason for the co-administration of Probenecid with penicillin.