<prompt> Which of the following statements about the biodisposition of penicillins and cephalosporins is NOT accurate?Oral bioavailability is affected by lability to gastric acidProcaine penicillin G is used intramuscular injectionRenal tubular reabsorption of beta-lactams is inhibited by probenecidNafcillin and ceftriaxone are eliminated mainly biliary secretion  <response>: Probenecid inhibits renal tubular secretion of penicillins not reabsorption Beta lactams eliminated by biliary route are: -- Ampicillin -- Nafcillin -- Ceftriaxone -- Cefoperazone Penicillin G has to be given by i.m. route because it is broken down by gastric acid decreases oral bioavailability. 