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Drug Testing - 5 stages that all drugs must pass through

Updated on July 5, 2012
It took a very long time for those pills to get on that spoon....
It took a very long time for those pills to get on that spoon.... | Source

Drug Testing in the Modern Age

Drugs, that is medicines, are a vital part of modern life. They are relied upon by so many for helping them feel better, curing them, and often saving their lives.

Most people use some sort of medicine and so the demand for them is always very high. But in order to make sure that all of these in-demand drugs are safe, drugs are put through a string of strict testing. In fact, so strict, that a drug takes on average 10-12 years and over 1 billion $USD to be developed.

Even before testing begins however, substances that are believed to be medicinal are analysed thoroughly for their active ingredient. This is identified molecularly so that it may be made synthetically rather than extracted, and so that computer models can be created and so testing can be performed on it.

1. Pre-clinical Testing

  • Before being tested on living animals, testing is done on isolated tissue cultures as well as just cells. This is to try to gauge whether or not the active compound (the thing trying to cure/alleviate a disease) is effective or not.
  • This is the stage at which most drugs fail, because even if there is just a small risk that a drug will harm human beings mildly, the consequence of that on a whole world scale of potentially 7 billion people (+ animals) is immense and small damage becomes too large to risk.
  • If the drug is seen to be effective and is intended for humans, then animal testing (if approved by the MHRA) will be used during the pre-clinical testing.

2. Clinical Trials - Phase I

  • A small group of healthy humans are used for testing. They are given differing doses and the data is recorded (in the UK MHRA in the UK).
  • The results are used to find out whether or not the active compound is being absorbed and metabolised by the body.
  • Other issues like whether or not the drug is excreted or building up in the right areas are explored.

3. Clinical Trials - Phase II

  • Between 100-300 humans with the targeted disease are treated with the drug in question in Phase II.
  • If the drug proves effective, Phase III commences.

4. Clinical Trials - Phase III

  • Between 1000-3000 volunteer patients are used.
  • They are split into two groups. One for being given the placebo (sugar pill - not a real drug to see if the effects are psychological and to have a point of reference for the results) and one the real active drug.
  • If there already is a drug that is being used to cure/alleviate the disease, then that drug is used in the place of a placebo.
  • During this phase, neither the doctors nor the patients know who has received the placebo.
  • If the people who did take the drug show much better results (with no more adverse effects) than the people taking the existing drug or placebo, then the drug is now allowed to be marketed commercially.

5. After Licensing Testing

  • Even after a drug has been given permission to be sold, it must still undergo testing and have data about its effectiveness collected in case of any long term side effects.
  • This also serves to provide information on how useful a new drug must be in order to beat the existing one in its function.

In Summary

The five trials that a drug must pass through in order to be allowed and maintain to be allowed to be sold on the market are the following:

  1. Pre-clinical Trials - using isolated cells, tissues and then living animals.
  2. Clinical Trials - Phase I - using a small group of healthy volunteers.
  3. Clinical Trials - Phase II - using a small group of volunteers with the target illness.
  4. Clinical Trials - Phase III - using a large group of volunteers with the target illness.
  5. After License Trials - having data about effectiviness recorded regularly.


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    • profile image

      ethanredford 4 years ago

      idont think it fair for animaltesting rats yes but no other animals like dogs and monkeys no

    • christopheranton profile image

      Christopher Antony Meade 5 years ago from Gillingham Kent. United Kingdom

      As somebody who needs to take regular medication, the reassurances that you give here about the testing of various drugs are very gratifying. I hope the pharmaceutical profession will always maintain those high standards.

    • WD Curry 111 profile image

      WD Curry 111 5 years ago from Space Coast

      Good job, but I was hoping you could help me pass the test.

      Oh, well, I guess I'll just stay freelance. Anyway, it was very interesting and you did well to provide links for more study.