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Bioequivalence studies
A bioequivalence study is done to compare the metabolism of two forms of a drug. The generic and the branded form of a drug can be compared. Another instance is when one dose of drug can be compared in different forms, for example one 40 mg tablet versus two 20 mg tablets of a drug.
During a bioequivalence study a subject is given one form of a drug and after a few days the subject is given the other form of the drug. Each time after the drug is given, blood tests are done to determine the levels of the drug in the blood of the subjects. The blood test results for the two forms of the drug are compared. If the tests show that the same amount of the two forms of the drug is delivered into the blood of the subjects at the same rate, then we say that bioequivalence has been established for the drugs.
Drug testing in animals cannot be used to say that bioequivalence has been established between drugs, the tests must be done in human beings. Healthy volunteers are recruited to participate in Phase I bioequivalence studies.
Interaction Studies
It is not enough to only understand what drugs do in the body, but also if the way they work and are broken down change when given together with other drugs. Interaction studies can be used to evaluate many aspects like the potential enhancement of treatment by giving drugs together or to detect an increase or decrease in function.
Sometimes drugs given together can have different side effects than medication given alone. This safety information is used to update prescribing information leaflets.
Interaction studies can be done on drugs that are already on the market, but sometimes the interaction between a newly developed drug and drugs that are marketed are tested.
Generally studies will run over two or more periods depending on how many different drugs are being tested. Normally only two drugs are given at the same time and the use of placebo (dummy drug that does not contain an active substance) can also be included. Depending on the design single or multiple doses may be given.
Other types of interaction studies that are common are food interaction studies. The absorption of some drugs is influenced when given with food. These studies will mostly have two periods. Volunteers will be fasted in one period and receive breakfast in the other. The study drug is given in both periods, usually as a single dose.
ADME Studies (Absorption, Distribution, Metabolism and Excretion)
ADME studies are specifically designed to evaluate the way that a drug is absorbed by the body, where it goes and how it is changed and broken down. It is important to know how the body gets rid of drugs and how long this takes.
ADME studies are done by administering a small amount of radio labelled drug to healthy volunteers. A radioactive substance is attached to the drug being tested and used to track the progression of the drug through the body. This is usually a 14C molecule. Samples are then collected until almost all of the radio labelled drug has left the body. This is normally done while staying in the unit, but occasionally if the drug stays in the body a long time, volunteers will be asked to collect urine and faecal samples at home and return them to the unit.
These studies normally have a screening day, one period in the unit and follow-up. Sometimes outpatient visits are also scheduled if samples are collected at home.
ADME studies are conducted with safety measures to reduce the risk of radioactivity to volunteers and staff. The risk is minimal and closely regulated by radiation safety committees.
ADME studies are specifically designed to evaluate the way that a drug is absorbed by the body, where it goes and how it is changed and broken down. It is important to know how the body gets rid of drugs and how long this takes.
ADME studies are done by administering a small amount of radio labelled drug to healthy volunteers. A radioactive substance is attached to the drug being tested and used to track the progression of the drug through the body. This is usually a 14C molecule. Samples are then collected until almost all of the radio labelled drug has left the body. This is normally done while staying in the unit, but occasionally if the drug stays in the body a long time, volunteers will be asked to collect urine and faecal samples at home and return them to the unit.
These studies normally have a screening day, one period in the unit and follow-up. Sometimes outpatient visits are also scheduled if samples are collected at home.
ADME studies are conducted with safety measures to reduce the risk of radioactivity to volunteers and staff. The risk is minimal and closely regulated by radiation safety committees.
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