Final answer:
Phase I pharmacodynamics involve assessing a drug's effects and safety, as well as its pharmacokinetic properties like ADME, to determine appropriate dosing and potential progression to further clinical trial phases.
Step-by-step explanation:
Phase I pharmacodynamics in the context of targeted drug development refer to the initial assessment of a drug's biological effects and safety profile in humans. During Phase I clinical trials, the pharmacokinetic properties such as absorption, distribution, metabolism, and excretion (ADME) are closely monitored. This phase involves single sub-therapeutic dose studies that, if tolerated, are escalated to multiple dose studies. If the drug demonstrates poor bioavailability, an unsuitable half-life, or is not well tolerated, it may be discontinued from further development. Phase I trials are critical for establishing a safe dosing range and deciding if the compound should advance to subsequent phases of clinical trial.