Watson E, et al. - Via performing this analysis, researchers sought to describe the pharmacokinetics (PK) of the strong analgesic tapentadol in 2-year-old to < 18-year-old patients with acute pain. In addition, they sought to inscribe the optimal dosing strategy for a confirmatory efficacy trial in this patient population. Dataset of 92 pediatric patients receiving a single tapentadol oral solution (OS) dose of 1.0 mg/kg bodyweight in two single-dose PK clinical trials was analyzed to obtain tapentadol concentrations. They used nonlinear mixed-effects modeling to perform population PK analysis. By performing simulations, tapentadol OS doses were sought in pediatric cases (2 to < 18 years) that would provide exposures comparable to those in adults taking safe and efficacious doses of tapentadol IR (50–100 mg every 4 hrs). A one-compartment model was identified as the best to describe tapentadol PK in children aged from 2 to < 18 years. For a typical case weighing 45 kg, the mean population apparent clearance was 170 L/h and apparent volume of distribution was 685 L. With increasing age, clearance, expressed in bodyweight units as L/h/kg, decreased whereas total clearance (L/h) increased. As per model-based simulations, children and adolescents aged 2 to < 18 years would exhibit efficacious tapentadol exposures similar to those in adults receiving tapentadol immediate release 50–100 mg every 4 hrs when administered a tapentadol OS dose of 1.25 mg/kg. Subsequent application of the proposed tapentadol OS dose was done in a confirmatory efficacy trial in 2 to < 18-year-old patients suffering from acute postsurgical pain.