Dose regimen selection in late-phase clinical trials is critical for successful drug development, the well-being of individual patients, and given the ongoing emergence of antimicrobial resistance, society as a whole. Herein we describe some of the animal pharmacokinetics-pharmacodynamics, human pharmacokinetic, and in silico modeling work that was conducted in an effort to maximize the probability of a positive clinical response to therapy and minimize the likelihood for exposure-related toxicity for doripenem in phase 3 clinical studies. Some of the dosing regimens identified have been validated as effective in phase 3 clinical studies (500 mg infused over 1 h every 8 h for complicated intra-abdominal infections), whereas others (1000 mg infused over 4 h every 8 h for hospital-acquired pneumonia) are undergoing clinical evaluation.