Availability of information for dosing injectable medications in underweight or obese patients

Purpose. Product information and pivotal studies on newly marketed injectable medications were reviewed to determine whether a weight descriptor was included and if information was provided for dosing patients with extremes of body weight. Methods. Products with new drug applications approved by the Food and Drug Administration between January 1, 2004, and January 30, 2009, were evaluated. Any information related to weight descriptors or dosing of patients with extremes of weight (body mass index of <18.5 or >40 kg/m²) relative to age and height was extracted from the product labeling or pivotal studies. Pharmaceutical companies were contacted if pivotal studies had not been published. The information was evaluated with a dosing usefulness score of 0-3; a score of 2 or greater was considered minimally adequate for dosing patients with extremes of weight. Results. Of the 84 medications evaluated, some reference to weight descriptors was found for 23 (27%). None had a calculated usefulness score of 2 or above based on information from product information or pivotal trials. Conclusion. Information from product labeling and pivotal studies involving newly marketed injectable medications is inadequate for dosing patients with extremes of weight.