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Phase I and Phase II Clinical Trials

Before a pharma company can launch a new drug in the market, it is imperative for the company to thoroughly test it.

The company performs clinical trials to evaluate the efficacy and safety of the drug. A company usually outsources these clinical trials to a reputed clinical research organization. There are four well defined phases in the clinical trial.

Phase I Clinical Trials:

The main goal of Phase I clinical trials is to determine the metabolic and pharmacological effects of the new drug, as well as drugs doses.

Phase I clinical trials are carried out on a group of healthy volunteers (often between 20 and 60 people). It includes the introduction of the drug to be tested in these human volunteers under close surveillance. These trials evaluate the dose-dependant effects and side effects of the drug.

The results of these Phase I trials are crucial, as they determine whether Phase II studies are warranted.

These studies are closely monitored and may be conducted on patients, but are usually conducted on healthy volunteer subjects. Clinical trials are designed to determine the metabolic and pharmacologic actions of the drug in humans and the side-effects associated with increasing doses. The best range of drug doses to test in the later study phases is ascertained. During Phase I, sufficient information about the drug's pharmacokinetics and pharmacological effects should be obtained to permit the design of well-controlled, scientifically valid, Phase II studies.

The goal of Phase I studies:

To see if the drug is safe and determine the likely dose range for later studies
To check it's effect on the body's metabolism and also the drug’s metabolism by the body.

Phase II Clinical Trials

Phase II clinical trials are held to determine the clinical efficacy of the drug in smaller numbers of patients with the target disease. Different research institutes offer different types of Phase II studies. It can range from small scale dose finding studies to something which is very similar to Phase III studies. Phase II clinical trials are very important as this is where a new drug can fail. Based on early efficacy data.

The goal of Phase II studies:

Efficacy of the drug
Side-effects on the body
Determination of appropriate dosages in smaller groups of patients

Phase III Clinical Trials

The aim of Phase III trials is to substantiate the findings of Phase II clinical trials. compare the drug to commonly used, existing treatments, and collect information that will allow the drug or treatment to be used safely. Phase III trials are very expensive since they are carried out on a larger group of patients (from 250 and up to 4000 or more). Often these studies are performed with patients from several hospitals or even countries.

Once the Phase III trials are completed, all the data (including data on animal studies, Phase I and Phase II trials) is collated and handed over to the respective Drug Control Authority of the country for licensing and registration.

The goal of Phase III studies:

Effectiveness and dose determination in large, diverse patient groups.
Compare the drug to commonly used, existing treatments
Collect information that will allow the drug or treatment to be used safely.
Screen for rare side effects

Phase IV Clinical Trials

Phase IV clinical trials are held post-marketing launch. Typically, these trials involve post-launch safety surveillance to check for any rare or long-term adverse effects over a much larger patient population and timescale than was possible during the initial clinical trials. If any major adverse effects are found, the competitive Drug Authority (or the manufacturing company) may withdraw or restrict the drug usage.

The goal of Phase IV studies:

To monitor long term effects of the drug
In depth study of the side effects and safety of the drug
To find out how well a drug works when it's used more widely than in clinical trials

Phase 0 (new phase suggested, alternative description: micro-dosing)

The FDA defines "microdose studies," or human phase 0 studies as trials in small numbers of healthy subjects who receive no more than 100 micrograms or less than one percent of a standard dose of a drug under investigation. Based on the strength of microdosing pharamacokinetic data, regulators will allow radically shortened preclinical programs in some cases.