Randomized exposure-controlled trials; impact of randomization and analysis strategies.

Aims: In the literature, five potential benefits of randomizing clinical trials on concentration levels, rather than dose, have been proposed: (i) statistical study power will increase; (ii) study power will be less sensitive to high variability in the pharmacokinetics (PK); (iii) the power of establishing an exposure-response relationship will be robust to correlations between PK and pharmacodynamics (PD); (iv) estimates of the exposure-response relationship are likely to be less biased; and (v) studies will provide a better control of exposure in situations with toxicity issues. The main aim of this study was to investigate if these five statements are valid when the trial results are evaluated using a model-based analysis.

Methods: Quantitative relationships between drug dose, concentration, biomarker and clinical end-point were defined using pharmacometric models.

An integrated model for the effect of budesonide on ACTH and cortisol in healthy volunteers.

Aims: Budesonide, a glucocorticosteroid, is used as a first-line treatment for asthma. The aim of the study was to develop a PK/PD model for the effect of budesonide on ACTH and cortisol.

Methods: The modelling data were generated by conducting a single-blind, randomized, placebo-controlled cross-over study.

NXY-059 does not significantly interact with furosemide in healthy volunteers.

NXY-059 is a free radical-trapping neuroprotectant that reduces infarct size and preserves brain function in animal models of acute ischemic stroke. Acute ischemic stroke patients receiving NXY-059 may also be exposed to diuretics for treatment of heart failure or hypertension. NXY-059 and furosemide are partly eliminated by active tubular secretion via an organic anion transporter.

Positron emission tomography microdosing: a new concept with application in tracer and early clinical drug development.

The realisation that new chemical entities under development as drug candidates fail in three of four cases in clinical trials, together with increased costs and increased demands of reducing preclinical animal experiments, have promoted concepts for improvement of early screening procedures in humans. Positron emission tomography (PET) is a non-invasive imaging technology, which makes it possible to determine drug distribution and concentration in vivo in man with the drug labelled with a positron-emitting radionuclide that does not change the biochemical properties. Recently, developments in the field of rapid synthesis of organic compounds labelled with positron-emitting radionuclides have allowed a substantial number of new drug candidates to be labelled and potentially used as probes in PET studies.