Clinical Trials
From DrugPedia: A Wikipedia for Drug discovery
Clinical Trials are conducted to determine whether new drugs or treatments are both safe and effective.
Clinical trials help physicians discover the answers to the following questions:
1.Is the treatment safe and effective?
2.Is the treatment potentially better than the treatments alredy existing?
3.What are the side effects of the treatment?
4.Does the treatment have any possible risks?
5.How well does the treatment work?
Contents |
[edit] Types of Clinical Trials
- Treatment trials : test experimental treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
- Prevention trials : look for better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include medicines, vaccines, vitamins, minerals, or lifestyle changes.
- Diagnostic trials : are conducted to find better tests or procedures for diagnosing a particular disease or condition.
- Screening trials : test the best way to detect certain diseases or health conditions.
- Quality of Life trials (or Supportive Care trials) : explore ways to improve comfort and the quality of life for individuals with a chronic illness.
[edit] Phases of Clinical Trials
Clinical trials are conducted in four different phases. The trials at each phase have a different purpose and help scientists answer different questions.
Phase 0 trials are also known as human microdosing studies and are designed to speed up the development of promising drugs or imaging agents by establishing very early on whether the drug or agent behaves in human subjects as was anticipated from preclinical studies. Distinctive features of Phase 0 trials include the administration of single subtherapeutic doses of the study drug to a small number of subjects (10 to 15) to gather preliminary data on the agent's pharmacokinetics (how the body processes the drug) and pharmacodynamics (how the drug works in the body).
A Phase 0 study gives no data on safety or efficacy, being by definition a dose too low to cause any therapeutic effect. Drug development companies carry out Phase 0 studies to rank drug candidates in order to decide which has the best PK parameters in humans to take forward into further development. They enable base go/no go decisions to be based on relevant human models instead of relying on animal data, which can be unpredictive and vary between species.
In Phase I trials, researchers test an experimental drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
In Phase II trials, the experimental study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.
In Phase III trials, the experimental study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the experimental drug or treatment to be used safely.
In Phase IV trials, Postmarketing Surveillance studies delineate additional information including the drug's risks, benefits, and optimal use.
| Phases | Number of Patients | Duration | Purpose | Percent of Drugs Successfully Tested |
|---|---|---|---|---|
| Phase I | 20-100 | Several Months | Safety | 70 % |
| Phase II | 100-500 | Several months to 2 years | Efficacy | 33 % |
| Phase III | 1000-8000 | 1-4 years | Safety, Efficacy and Dosage | 25-30 % |
| Phase IV (Post-Market Survelliance) | - | - | drug's risks, benefits, and optimal use | - |
[edit] Participation in Clinical Trails
Participants in clinical trials can play a more active role in their own health care, gain access to new research treatments before they are widely available, and help others by contributing to medical research.
All clinical trials have guidelines about who can participate. Using inclusion/exclusion criteria is an important principle of medical research that helps to produce reliable results. The factors that allow someone to participate in a clinical trial are called "inclusion criteria" and those that disallow someone from participating are called "exclusion criteria". These criteria are based on such factors as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. Before joining a clinical trial, a participant must qualify for the study. Some research studies seek participants with illnesses or conditions to be studied in the clinical trial, while others need healthy participants. It is important to note that inclusion and exclusion criteria are not used to reject people personally. Instead, the criteria are used to identify appropriate participants and keep them safe. The criteria help ensure that researchers will be able to answer the questions they plan to study.
[edit] Informed Consent
Informed consent is the process of learning the key facts about a clinical trial before deciding whether or not to participate. It is also a continuing process throughout the study to provide information for participants. To help someone decide whether or not to participate, the doctors and nurses involved in the trial explain the details of the study.
[edit] Benefits and Risks of participating in a Clinical Trial
Benefits
Clinical trials that are well-designed and well-executed are the best approach for eligible participants to:
- Play an active role in their own health care.
- Gain access to new research treatments before they are widely available.
- Obtain expert medical care at leading health care facilities during the trial.
- Help others by contributing to medical research.
Risks
There are risks associated with clinical trials.
- There may be unpleasant, serious or even life-threatening side effects to experimental treatment.
- The experimental treatment may not be effective for the participant.
- The protocol may require more of their time and attention than would a non-protocol treatment, including trips to the study site, more treatments, hospital stays or complex dosage requirements.
[edit] Clinical Trial Protocol
A Clinical Trial Protocol is a document that describes the objective(s), design, methodology, statistical considerations, and organization of a clinical trial. The protocol usually also gives the background and reason the trial is being conducted, but these could be provided in other documents referenced in the protocol (such as an Investigator's Brochure).
The protocol contains a study plan on which the clinical trial is based. The plan is designed to safeguard the health of the participants(while limiting their financial liablity) as well as answer specific research questions. The protocol describes, among other things, what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and the length of the study. While in a clinical trial, study participants are seen regularly by the research staff (usually medical doctors and/or nurses) to monitor their health and to determine the safety and effectiveness of the treatment(s) they are receiving.
The format and content of clinical trial protocols sponsored by pharmaceutical, biotechnology or medical device companies in the United States, European Union, or Japan has been standardized: they are written to follow the Good clinical practice guidance issued by the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). Regulatory authorities in Canada and Australia also follow the ICH guidance.
Clinical trial protocols for other clinical trials do not necessarily follow the standard format.
The existence of a clinical trial protocol allows researchers at multiple locations (in a multicenter trial) to perform the study in exactly the same way, so that their data can be combined as though they were all working together. The protocol also gives the study administrators (often a contract research organization) as well as the local researchers a common reference document for the researchers' duties and responsibilities during the trial.
[edit] Regulatory Agencies Using ICH Guidelines for Clinical Trial Protocol
- Food and Drug Administration (FDA)
- European Medicines Agency (EMEA)
- Japanese Ministry of Health, Labour and Welfare (MHLW)
- Health Canada
- Australian Therapeutic Goods Administration (TGA)
