Dose-Ranging Study
A Phase II clinical trial that tests multiple dose levels simultaneously to identify the optimal dose for Phase III trials. Dose-ranging studies balance efficacy against tolerability to select the dose most likely to succeed in pivotal trials.
Technical Context
Phase IIb dose-ranging studies randomise patients to 3-5 dose levels plus placebo. Design considerations: dose spacing (geometric progression, e.g. 1mg, 3mg, 10mg, 30mg — covering a wide range with equal ratios), sample size per arm (typically 30-100 patients, balancing precision against cost), and treatment duration (long enough to observe near-maximal effect). Analysis: dose-response modelling using Emax models (hyperbolic curve fitting), linear or log-linear models, or more flexible approaches (MCP-Mod — multiple comparisons procedure combined with modelling). The selected Phase III dose should be on the plateau of the dose-response curve (near-maximal efficacy) with acceptable tolerability. Tirzepatide Phase II identified 5mg, 10mg, and 15mg as the Phase III doses from a broader range tested.