How Clinical Trials Move from Lab to Patient

Turning a promising compound into an approved medicine is a long, structured process. It does not happen in a single step, and the time it takes is a feature of the system rather than a flaw. Below I walk through how research moves from the laboratory to patients through clinical trials, explaining the major stages in plain language. It describes the process in general terms and makes no claims about any particular compound.

If you want the short version of the idea, it is this: each stage exists to answer one question before the next, more demanding question is asked. Skipping a stage does not save time so much as move the uncertainty somewhere less visible.

It starts in the laboratory

Long before any person is involved, research begins at the preclinical stage. Scientists study a compound in laboratory systems, examining its chemistry, how it behaves, and its effects in cell-based and animal models. This is also where early pharmacokinetics is studied: how a substance is absorbed, distributed, metabolised and eliminated.

Pharmacokinetics is a mouthful, but the idea is simple. It describes what the body does to a substance, whereas pharmacodynamics describes what the substance does to the body. Both matter, and researchers want a working picture of each before anyone is exposed to the compound. Our piece on preclinical vs clinical research goes further into why findings from cells and animals cannot simply be assumed to carry over to people.

Preclinical work serves a gatekeeping role. Only compounds that show an acceptable initial profile, and for which there is a reasonable scientific rationale, proceed toward human studies. Most candidate compounds never make it past this stage.

That attrition is not a sign that something has gone wrong. Screening out unsuitable candidates early is exactly what the stage is for, and it is far better to learn a compound behaves poorly in a laboratory model than in a human volunteer.

The phases of clinical trials

If a compound progresses, it enters clinical trials, which are conventionally divided into phases. Each phase has a distinct purpose and builds on the last. The general concept is described on Wikipedia's clinical trial page, and we cover the sequence in more detail in the phases of a clinical trial.

Phase 1

The first human studies are usually small and focus primarily on safety. Researchers examine how the compound is tolerated, study its pharmacokinetics in people, and look for any adverse effects. The emphasis is on understanding the basic behaviour of the compound in humans, not on demonstrating an outcome.

A common misreading is to treat a first-phase result as a verdict on whether something "works". It is not designed to answer that. A small early study can tell you a compound was tolerated under specific conditions; it cannot tell you much about benefit.

Phase 2

If a compound passes the first phase, larger studies explore how it performs in the population of interest and continue to monitor safety. This phase often helps researchers understand appropriate dosing and refine the questions that a later trial will need to answer.

Think of this as the stage where the research question gets sharpened. Investigators learn which measurements are sensible, which participants are most relevant, and what a properly sized later study would need to look like. Plenty of programmes stop here, because the signals are not strong enough to justify a larger commitment.

Phase 3

The third phase involves larger and more rigorous studies, frequently using randomisation and control groups to produce strong evidence. These trials are designed to generate the high-quality data that regulators require when deciding whether a compound should be approved.

Randomisation matters because it spreads known and unknown differences between participants across the groups being compared, so that a difference in results is more likely to reflect the intervention itself. If those terms are new to you, randomised controlled trials explained is a good companion read.

How trials are designed to reduce bias

The phase labels tell you the order of events, but they say little about the quality of a particular study. Two later-phase trials can differ enormously in how well they are built, and I'd argue that design quality deserves as much attention as the phase number when you read a headline.

Several features are worth recognising. A control group provides a comparison, so that changes seen in participants can be set against what happens without the intervention being tested. Blinding means participants, and often the researchers assessing them, do not know who received which treatment, which limits the influence of expectation. A pre-specified plan, setting out in advance what will be measured and how it will be analysed, makes it harder to go hunting for a favourable result after the fact.

Sample size matters too. A very small study can produce striking-looking numbers purely by chance, and a larger one gives a steadier picture. Equally, it helps to ask what was actually measured. Some studies track a laboratory marker, others track something participants would notice in daily life, and the difference between those is explained in surrogate vs clinical endpoints.

The role of the regulator

In Australia, the Therapeutic Goods Administration evaluates the evidence generated through this process. If a compound's data supports approval, the product may be entered on the Australian Register of Therapeutic Goods, the register of products approved for supply. The agency publishes its own information at the TGA website, and our explainer on how the Therapeutic Goods Administration works covers the regulator's role in plain terms.

Until that point, a compound remains investigational and, in regulatory terms, unapproved. Trials themselves operate under strict ethical and regulatory oversight, including independent ethics review and informed consent for participants.

It helps to be precise about the word "unapproved". It describes a regulatory status, not a judgement about whether a compound is interesting or dangerous. For a closer look at the term, see what "investigational medicine" really means.

Informed consent deserves a moment of its own. Participants are given information about the purpose of a study, what is involved, and the known and possible risks, and they can decline or withdraw. Independent ethics committees review the plan before it starts, so the people judging whether a study is acceptable are not solely the people running it.

Why it takes so long

People sometimes ask why the process cannot be faster. The structured, sequential design exists for good reasons:

• Safety first. Early phases prioritise understanding risk before larger numbers of people are involved.
• Evidence quality. Rigorous later-phase trials are designed to distinguish genuine effects from chance or bias.
• Oversight. Ethical review and regulatory scrutiny add necessary checks at each stage.

There is a practical side as well. Recruiting suitable participants, following them for long enough to see meaningful results, analysing the data and then preparing it for regulatory review are all slow tasks. None of them can be hurried without some cost to reliability.

Even after approval, monitoring often continues, sometimes described as post-market surveillance, to track how a product performs in wider use. Trials involve selected participants under controlled conditions, and everyday use is messier. How information from routine use relates to trial findings is the subject of real-world evidence vs trial data.

Common mistakes when reading research claims

A few patterns come up again and again. The first is treating an early result as a conclusion. A laboratory finding, or a small first-phase study, is a starting point for further work, and it is routinely reported as if it were an ending.

The second is leaning on personal accounts. A story from one person can be sincere and still tell you nothing reliable about cause and effect, because it has no comparison group and no way to rule out coincidence. That distinction is spelled out in why anecdotes are not evidence.

The third is overlooking who paid for the work and how it was reported. Funding does not automatically invalidate a study, but it is a fair thing to check, and conflicts of interest in research explains why disclosure matters. A fourth, simpler mistake is to assume that a product being sold or discussed publicly means it has been through this process. It may not have, and Australian rules around how therapeutic goods can be promoted are set out in advertising rules for therapeutic goods.

None of this requires a science degree. It mostly requires asking where a claim sits in the pipeline, who tested it, how, and in whom.

What this means for reading the news

Understanding the phases helps you interpret research announcements accurately. A finding from a laboratory or early-phase study is genuinely interesting, but it is an early signal, not a conclusion. A result from a large, well-designed later-phase trial carries far more weight. And approval by a regulator represents the culmination of the entire process.

When you see coverage of cannabinoids, peptides or any other compound in development, locating the work within this framework tells you how much confidence is warranted. A short checklist can help: was this in cells, animals or people; how many participants; was there a comparison group; was it peer reviewed; and has a regulator assessed the evidence?

Headlines rarely answer those questions, so it is worth looking for the original study or an official summary. Where that is not possible, caution is a perfectly reasonable default. This article describes the clinical trial process in general educational terms and is not medical advice.