Question

when penicillin G is used together with a probenecid, the half-life of penicillin G is increased significantly. Explain why probenecid can increase penicillin G's half life

Answer 1

Probenecid is used in combination with penicillin to prolong the plasma half-life and increase serum concentrations. The typical dose for this effect is 1 g daily.

amount of penicillin excreted willbecome less since probenecid competes with penicillin in the renal tubular secretion. Thusprolonged duration of action of penicillin takes place which increases theantibacterial action.

Probenecid is a renal tubular blocking agent. It inhibits the reanl transport of antiboitics like penicillin.

The half-life of probenecid in plasma is 4 to 12 hours and depneds on the quantity of dose given to the patient. Renal excretion is the major route of elimination of the metabolites; excretion of the parent drug is minimal and is dependent on urinary pH.

Penicillin G is benzylpenicilin It is excreted through tubular excretion and glomerular filtration has a plasma half life of 30 minutes. Probenecid increases the half life of penicillin from an average of 40.4 to 104.3 minutes