The authors sought to quantify the influence of the CYP3A and P-glycoprotein inhibitor ketoconazole on the pharmacokinetics of everolimus in healthy subjects. This was a 2-period, single-sequence, crossover study in 12 healthy subjects. In period 1, subjects received the reference treatment of a single 2-mg dose of everolimus. In period 2, they received the test treatment of ketoconazole 200 mg twice daily for a total of 8 days and a single dose of everolimus coadministered on the fourth day of ketoconazole therapy. The test/reference ratio and 90% confidence interval were derived for everolimus maximum concentration and area under the curve. During ketoconazole coadministration, everolimus maximum concentration increased 3.9-fold (90% confidence interval, 3.4-4.6) from 15 +/- 4 ng/mL to 59 +/- 13 ng/mL. Everolimus area under the curve increased 15.0-fold (90% confidence interval, 13.6-16.6) from 90 +/- 23 ng*h/mL to 1324 +/- 232 ng*h/mL. Everolimus half-life was prolonged by 1.9-fold from 30 +/- 4 hours to 56 +/- 5 hours. Everolimus did not appear to alter ketoconazole predose concentrations. Given the magnitude of this drug interaction, use of ketoconazole should be avoided if possible in everolimus-treated patients.

Aims We sought to define the influence of verapamil, an inhibitor of CYP3A and P‐glycoprotein, on the pharmacokinetics of everolimus, a substrate of this enzyme and transporter. Methods This was a two‐period, single‐sequence, crossover study in 16 healthy subjects. In period 1 subjects received a single 2 mg oral dose of everolimus. In period 2 they received verapamil 80 mg three times daily for a total of 6 days and a single 2 mg dose of everolimus co‐administered on the second day of verapamil therapy. Results During verapamil co‐administration, everolimus Cmax increased 2.3‐fold (90% CI, 1.9, 2.7) from 21 ± 8 to 47 ± 18 ng ml−1 and AUC increased 3.5‐fold (90% CI, 3.1, 3.9) from 115 ± 45 to 392 ± 142 ng ml−1 h. Everolimus half‐life was only prolonged to a minor extent (32 ± 6 vs. 37 ± 6 h). Verapamil predose concentrations doubled from 32 ± 16 to 74 ± 42 ng ml−1 after single dose administration of everolimus. Conclusions Multiple dosing with verapamil increased blood concentrations of everolimus after a single dose by an average 3.5‐fold. During verapamil treatment, dose reduction for everolimus should be made guided by blood monitoring and for verapamil by blood pressure monitoring.

Objective: To review published algorithms for guiding the use of methylphenidate (MPH) in the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) in children and adolescents. Methods: A consensus roundtable of 12 experts was convened to review the evidence for the safety and efficacy of MPH in the treatment of ADHD, as well as the published algorithms and practice guidelines for using MPH. The experts reviewed the algorithms for practicality and acceptability by clinicians. Results: Algorithms that included MPH commonly selected it as the initial medication to be employed in the treatment of children with ADHD. Factors involved included its high efficacy, good safety record, and the ubiquitous nature of its appearance in the ADHD treatment literature. Conclusions: MPH should be considered as the first medication to be used in a treatment algorithm for children and adolescents with ADHD.

More than half of all drugs used in medical practice are metabolized by cytochrome CYP3A. Coadministration of drugs that share this elimination pathway may lead to pharmacokinetic drug interactions. Efforts are underway by clinical, drug development and regulatory scientists to classify CYP3A-related drug interactions with the ultimate goal of improving guidance for clinical intervention. The CYP3A inhibitory classification system ranks inhibitors according to the fold-increase in area-under-the-curve (AUC) of a probe substrate as: strong (> or =5-fold), moderate (>2.0- to 4.9-fold), or weak (< or =2.0-fold). This classification system was applied to characterize everolimus as a CYP3A substrate.Methods. Five open-label crossover drug interaction studies were performed in 12-16 healthy subjects each. Subjects received a single 2 mg dose of everolimus alone and again during single- or multiple-dose treatment with the probe inhibitors ketoconazole, erythromycin, verapamil, cyclosporine and atorvastatin.Results. The fold-increase in everolimus AUC was: 15.0 with the strong inhibitor ketoconazole; 4.4, 3.5 and 2.7 with the moderate inhibitors erythromycin, verapamil and cyclosporine; and no change with the weak inhibitor atorvastatin. Subjects with low baseline AUCs when everolimus was given alone tended to have AUC increases of a higher magnitude (more potent interaction) in the presence of an inhibitor.Conclusions. Strong CYP3A inhibitors should be avoided when possible during everolimus treatment as compensatory everolimus dose reductions could be difficult to manage. Everolimus therapeutic drug monitoring should be used to guide individualized dose adjustments when moderate CYP3A inhibitors are added to or withdrawn from the regimen. Routine everolimus therapeutic drug monitoring should be sufficient to determine whether dose adjustments are needed when weak CYP3A inhibitors are coadministered. This rational and systematic approach to drug interactions on everolimus yielded clinically useful, structured guidelines for dose adjustment.