IMPORTANCE Some new drug applications fail because of inadequate drug performance and others are not approved because the information submitted to the US Food and Drug Administration (FDA) is unsatisfactory to make that determination. Resubmission of failed applications is costly, delaying marketing approval and the availability of new drugs to patients.OBJECTIVE To identify the reasons that FDA marketing approval for new drugs was delayed or denied. DESIGN, SETTING, AND PARTICIPANTSA retrospective review of FDA documents and extraction of data were performed. We examined all drug applications first submitted to the FDA between 2000 and 2012 for new molecular entities (NMEs), which are active ingredients never before marketed in the United States in any form. Using FDA correspondence and reviews, we investigated the reasons NMEs failed to obtain FDA approval. MAIN OUTCOMES AND MEASURESReasons for delayed FDA approval or nonapproval of NME applications. RESULTSOf the 302 identified NME applications, 151 (50%) were approved when first submitted and 222 (73.5%) were ultimately approved. Seventy-one applications required 1 or more resubmissions before approval, with a median delay to approval of 435 days following the first unsuccessful submission. Of the unsuccessful first-time applications, 24 (15.9%) included uncertainties related to dose selection, 20 (13.2%) choice of study end points that failed to adequately reflect a clinically meaningful effect, 20 (13.2%) inconsistent results when different end points were tested, 17 (11.3%) inconsistent results when different trials or study sites were compared, and 20 (13.2%) poor efficacy when compared with the standard of care. The frequency of safety deficiencies was similar among never-approved drugs compared with those with delayed approval (43 of 80 never approved [53.8%] vs 37 of 71 eventually approved [52.1%]; difference, 1.7% [95% CI, −14.86% to 18.05%]; P = .87). However, efficacy deficiencies were significantly more frequent among the never-approved drugs than among those with delayed approvals (61 of 80 never approved [76.3%] vs 28 of 71 eventually approved [39.4%]; difference, 36.9% [95% CI, 20.25% to 50.86%]; P < .001).CONCLUSIONS AND RELEVANCE Several potentially preventable deficiencies, including failure to select optimal drug doses and suitable study end points, accounted for significant delays in the approval of new drugs. Understanding the reasons for previous failures is helpful to improve the efficiency of clinical development for new drugs.

Antimicrobial resistance is increasing among bacterial pathogens. In particular, organisms producing extended spectrum beta-lactamase enzymes (ESBLs) and AmpC chromosomal beta-lactamase enzymes are resistant to third generation cephalosporins and pose a formidable challenge in the management of seriously ill patients. Carbapenems are a class of broad-spectrum antibiotics with stability against ESBL and AmpC chromosomal beta-lactamases. They are well tolerated by patients. This review will examine the pharmacokinetic and pharmacodynamic properties of two carbapenems imipenem and meropenem and discuss their clinical use in children. References are limited to the English language and extend back to 1980. Sources include computerized databases such as MEDLINE searched using PubMed, and bibliographies of recent articles and books. Approximately 50% of the articles initially reviewed are included in the bibliography. Carbapenems are efficacious in the treatment of a variety of bacterial infections including meningitis, pneumonia, intraabdominal infections, bone, joint and urinary tract infections. The broad spectrum activity and comparatively low toxicity of carbapenems make them valuable therapeutic agents in the treatment of seriously ill patients with bacterial infections. These agents should be used judiciously in order to minimize the risk for development of carbapenem-resistant pathogens.