Phase IV Trial
Definition
Study after approval, in ordinary clinical use rather than in a selected trial population. Long-term and rare harms surface here, which is why an approval is not the end of the evidence.
What this means for research sourcing
Understanding evidence quality helps researchers prioritize compounds. Volta's research library summarizes the literature behind stocked compounds.
Related Terms in Evidence & Research
Preclinical
Work done before any human administration: cell culture, tissue and animal models. Most peptides discussed in this field have preclinical evidence only, and rodent findings fail to carry across to humans far more often than they succeed.
In Vitro
In glassware: cells, tissue or isolated enzymes outside a living organism. Concentrations used in vitro are frequently unreachable in a body, which caps what such a result can predict.
In Vivo
In a living organism, animal or human. In-vivo work accounts for absorption, distribution, metabolism and clearance in a way cell work cannot, which is why an in-vitro effect so often disappears in vivo.
Blinding
Withholding treatment allocation from participants, investigators or outcome assessors. It fails in practice whenever a compound has obvious effects, which is a known weakness of trials in this area.
Double-Blind
Neither participants nor investigators know who is in which arm, so expectation cannot colour reported symptoms or outcome assessment. It is a design feature, not a guarantee, and papers increasingly report whether blinding held.
Open-Label
Everybody knows who is receiving what. Open-label extensions following a blinded trial give useful long-term safety data, and their efficacy figures are not placebo-controlled and should not be read as though they were.
Placebo
An inactive preparation made to look like the active one, given to the comparison arm. Placebo groups routinely improve, which is exactly why an uncontrolled result cannot be read as evidence of an effect.
Placebo-Controlled
A design in which the comparison arm receives placebo rather than nothing or another active agent, isolating the intervention's own contribution to whatever changed.