Antibacterial activity and pharmacokinetics of bacampicillin and ampicillin

Single equimolar oral doses of bacampicillin and ampicillin were given to 9 healthy subjects on a crossover randomized basis. Data were interpreted in terms of a 3-compartment pharmacokinetic open model. Intestinal absorption of bacampicillin was found to be faster and more complete than that of ampicillin, yielding an increase in bioavailability of 30% to 40% as measured by the area under serum levels curve, the urinary excretion and absorption rate constants. After the administration of bacampicillin, much higher and sharper peaks were achieved in the serum and in the "tissue" water than after the administration of ampicillin. The maximum bactericidal dilution (MBD) of the serum samples taken 1 hr after the administration of the antibiotics against 10 strains of Diplococcus pneumoniae was higher following bacampicillin (p less than 0.01), as was the MBD of the 0 to 2 hr urine specimens against 10 strains of Escherichia coli. Further clinical trials are required to accurately assess the possible greater therapeutic effectiveness of bacampicillin than of ampicillin.