Phase 1 Clinical Trial

What is Phase 1 Clinical Trial?

Phase 1 clinical trial is the first phase of the clinical research process. It involves testing new or experimental drugs on humans for treatment. The aim is to determine a compound’s tolerability, safety, best dose, side effects, and pharmacokinetics (PK).

Clinical trials are key research tools only performed when there is a good reason that a new drug, test, or treatment may improve patients’ lives.

Clinical trials are not directly held. Before these trials, tests and treatments are assessed in pre-clinical research that is not done with people.

Phase 1 trials aim to find the most competent dose for a new or improved drug with the fewest side effects.

Phase 1 trials usually involve a small number of participants, often between 20 and 80, starting with very low doses.

The drug may help patients; however, the motive is to test a drug’s safety. If a drug passes Phase 1 safety evaluations, it progresses to Phase 2, which further assesses effectiveness and safety.

Phase 1 Clinical Trial – Everything You Need to Know About It

Phase 1 clinical trials are designed primarily to accumulate short-term safety and pharmacological data. These studies are the first to involve people. However, the number of patients involved is small, and they receive a very low amount of doses.

The purpose of phase 1 studies is to find the highest dose of the new treatment without causing any severe side effects. The treatment is first tested in the lab and on animals.

Key Takeaways

  • Phase 1 is the first clinical trial phase overseen by the Center for Drug Evaluation and Research (CDER).
  • It begins after the research and development of a new drug. The aim is to test the safety of a new drug by establishing its side effects.
  • A few participants are involved in this initial trial phase, starting with a low dose that is gradually increased while they are closely observed.
  • If side effects are rare, the next few trial participants get a higher dose.
  • The process is continued until a dose achieves the desired therapeutic effect without unacceptable side effects.
  • Approximately 70% of drugs that complete Phase 1 trials proceed to Phase 2.
  • Phase 1 clinical trials often carry the most potential risk. However, patients who have tried all other treatment options and are suffering from life-threatening illnesses choose to join such trials. Also, it has been noticed that these studies do help some patients.
  • Clinical trials, especially phase 1 trials, are expensive. They can cost between $1.5 million and $6.5 million.

Phase 1 Clinical Trial – The Process

Phase 1 clinical trials typically recruit 20 to 100 participants, whether healthy volunteers or patients, depending on the study’s focus. These trials are often administered by contract research organizations (CROs) that conduct studies on behalf of the research investigators or pharmaceutical companies.

Clinical trials are often conducted in clinical settings where participants receiving the drug are closely monitored.

Phase 1 trials normally study dose escalation to find the best and safest dose. This long and grueling process enables vital information about the drug’s effects.

This information facilitates the design of scientifically valid and well-controlled phase 2 studies.

Phase 2 clinical trials focus on the drug’s effectiveness in patients with the disease or condition under study, and Phase 3 trials compare the new treatment with the standard existing treatment. Phase 4 tests the drug’s effects on the population after it is approved by the FDA.

Phase 1 Trial Designs

Phase 1 clinical trials can include various study designs, such as Single Ascending Dose and Multiple Ascending Dose studies. Let us learn about it.

  • Single Ascending Dose

In Single Ascending Dose trials, small groups of participants, often starting with three, receive a single dose of the drug. They are then observed and closely monitored.

If they do not exhibit any adverse effects, the compound is deemed well tolerated, and the dose is escalated. It occurs within the same group, or a new group of subjects is given a higher dose.

Dose escalation is continued until the maximum dose has been attained or intolerable side effects become apparent. Dose escalation is terminated if unacceptable toxicity is observed, typically not specified by a proportion such as one-third of participants. The previous dose is then declared as the maximally tolerated dose.

  • Multiple Ascending Dose

Multiple Ascending Dose studies are conducted to elucidate the compound’s pharmacokinetics and pharmacodynamics. To assess tolerability and safety, a group of patients receives dose levels, and dosing intervals are selected.

At various time points, samples are collected and analyzed to determine how the body processes the drug. Subsequently, the dose is escalated for further participants to determine the safety level for repeat dose administration.

  • Food Effect

The food effect is a short trial designed to assess differences in the compound’s absorption when administered after a specifically designed meal.

Such studies are conducted following a crossover design with volunteers given drugs on different occasions while fasting and after being fed. These studies contribute to the prescription as to when drugs should be administered.

Phase 1 Clinical Trial – Is the Treatment Safe?

In the United States, the development and approval of drugs are complex processes. The treatment goes through scientific oversight that makes the treatment safe to a certain extent.

  • Institutional Review Board (IRB)

An IRB is an independent committee of members, including doctors, statisticians, and community members who sponsor a clinical trial. The purpose is to ensure that the rights of the participants are protected and that the proper protocols and ethics are followed.

All U.S. clinical trials require an IRB. An IRB approves research that deals with significant medical questions responsibly and scientifically. It also keeps a check on the ongoing results of the trial.

  • Office for Human Research Protections

The Office for Human Research Protection (OHRP) under the U.S. Department of Health and Human Services (HHS) oversees the research done or supported by HHS. The OHRP protects the rights and well-being of research participants. It develops educational programs and offers advice on research-related issues.

  • Food and Drug Administration

In the United States, The Center for Drug Evaluation and Research (CDER), a division of the U.S. Food and Drug Administration (FDA), manages clinical trials. The FDA reviews applications for new drugs or medical devices before testing them directly on humans and ensures that the proposed studies have informed consent and protection for human subjects.

  • Patient Rights: Informed Consent

The FDA protects participants in clinical trials and ensures that they have reliable information. Researchers must provide participants with complete and accurate information about the trial.

Prospective participants are required to sign an “informed consent” document indicating the research’s known risks, and they can leave the trial at any time.

Informed consent is giving all the details and facts to the trial participants. It includes information on the tests, treatments, benefits, and risks involved in the trial. It happens before the trial begins and during the trial.

Phase 1 Clinical Trial – Patients’ Benefits of Participating

A well-designed and executed clinical trial allows participants to play an active role in improving their health care. Here are some of the other additional benefits.

  1. Phase trial 1 helps reduce or control the disease. When other treatments have failed, a patient can benefit from participating.
  2. Patients can obtain expert medical care at leading healthcare facilities where they feel satisfied overall with their experiences.
  3. As a part of the phase 1 trial, a patient undergoes routine physical examination that helps them receive more information about their disease and alleviates some fear about the severity of their disease.
  4. The nature of toxicity reported in the phase 1 clinical trial positively impacts the patient as their every symptom is scrutinized. The participants feel empowered as they attempt to control the disease and contribute to the health of future patients.

Phase 1 Clinical Trial – Patient Risks of Participating

Some researchers view early access to a helpful drug as a benefit; however, this early access may also be risky. Here are some risks involved in participating in phase 1 clinical trials.

  1. The primary risk is death. The investigatory agent or malignancy progression or complications can cause it.
  2. Additionally, patients may also experience the risk of acute or delayed toxicities, which might not be detected until the phase 1 clinical trial is complete.
  3. Patients usually do not feel better or satisfied until their trial participation is complete.
  4. Several early-phase trials require fresh biopsies. These are subject to risks without any direct benefit to the patient.


Phase 1 clinical trial is the first step towards medical studies where a new or improved drug is tested on humans. It involves risks as well as benefits associated with it.

The primary purpose is to determine if a drug is safe and determine the best suitable dose. Yet, the benefits of phase 1 clinical trials may outweigh the risks. They bring hope by improving survival.

Participating in these clinical trials is a personal decision, and a patient can leave the problem anytime. Talk with your doctor about all the available treatment options; you can make a better choice together!

See Also

Dental Implants Clinical Trials

What is Medicare

What is a Trial Medicine

Current Version
April 8, 2021
Written By
Victoria Abigail Friedland
April 28, 2024
Updated By
Franco Cuevas, MD

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