Phase 1 Clinical Trials

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Once a drug / device is tested in the lab and/or on animals, the data is submitted to the regulatory authority to get approval for performing Clinical Trial. This is called IND (Investigational New Drug) filing, the study substance is termed as IMP (Investigational Medicinal Product).
                  Phase 1 clinical trials are done to demonstrate that the experimental medication or treatment is safe for humans and to determine the safest dose of a drug and to determine the best route of administration i.e. how the drug should be given (e.g. whether to be swallowed orally / or to be injected intravenously / or to be injected intramuscularly). Other areas of Phase 1 study include pharmacokinetics (absorption, distribution, metabolism and excretion) and pharmacodynamics. Multiple Phase 1 studies may be required to demonstrate the safety of the IMP, It should be understood that a single Phase 1 trial may not allow the drug to advance to the next level (Phase 2).

A phase 1 clinical trial usually requires a small number of people (subjects) usually less than 100. Most phase 1 trials are done in normal healthy subjects but some phase 1 studies are done only in patients with the target disease e.g. Cancer patients (Target disease is the disease for which the IMP is being developed. For safety and ethical reasons patients may be used for example as in cases of cancer or HIV patents with advanced disease may had all the existing treatment available to them. Due consideration of the risk-benefit ratio is done when patients are recruited in Phase 1 studies as patents may benefit from the new treatment in the trial, but there are chances that many patients won't benefit from the trail

Given below are some example cases of Phase 1 studies: (Source

Study in patients of small cell cancer to estimate the MTD (maximum tolerated dose) at a dose level up to 50 mg/day
A dose escalation study to determine the MTD and the dose limiting toxicities of 'XXX drug' in subjects of Chronic Idiopathic Myelofibrosis
Trial of 'XXX' Hookworm vaccine in normal Brazilian Adults.
Safety and Tolerability Study of 'XXX' in Healthy Subjects

Subjects are recruited very slowly onto phase 1 trials. The first group of subjects to take part are given a very small dose of the drug. If all goes well, the next group have a slightly higher dose. The dose is gradually increased with each group. The researchers monitor the effect of the drug, until they find the best dose to give. This is called a dose escalation study phase 1 study.

Phase I trials are usually conducted with open label, i.e. the subjects are aware of the drugs that they are being given.  Subjects are monitored closely to check their tolerance of the drug and incidents of side effects. Depending on the study, samples of blood, urine or stool and other physiological information may be obtained for analysis to evaluate absorption, distribution, metabolism and elimination of the drug in the body. Other observations about how the subject feels (e.g. pain, headache, fever, malaise and irritability), and vital signs (blood pressure, heart rate) and behavioral matters are taken into account. Depending on the complexity of the trial, the trial may last from several months to a year and may cost few millions.

If a treatment appears safe at the end of a phase 1 clinical trial, it may then enter a phase 2 clinical trial.

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