B1.3 Use and Abuse of Drugs


New Drugs

Drugs are chemicals that affect how the body works. Scientists are continually developing new drugs.

Drugs are tested for toxicity, efficacy and the optimum dose:

  1. In the laboratory - Drugs tested on cultures of cells and tissues and then live animals. These models help to predict how the drugs may behave in the human body.
  2. Clinical trials: stage 1 - healthy volunteers are given a very small dose of the drug to check that the drug is not toxic. 
  3. Clinical trials: stage 2 - patients with the disease that the drug is developed for are given different doses of the drug to test efficacy and the optimum dose.

In clinical trials, the test group receives the new drug. The control group receives the existing drug for that illness, or placebos. The results are compared and any difference suggests how well the new drug works.

Placebo- identical to the drug but doesn't contain the drug

Double-blind trial - both volunteers and researchers don't know which group the volunteers are in

Blind trial - volunteers don't know which group they're in, but researchers do

Why blind trials? To eliminate bias and researchers are more objective about results

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Statins and thalidomide


  1. Developed as a sleeping pill
  2. Seemed to control morning sickness in pregnant women- so was prescribed for this use... However, thalidomide was not tested on pregnant women
  3. Caused severe limb abnormalities in these women's children
  4. Then banned and drug testing made more thorough and rigorous
  5. Now used to treat diseases such as leprosy and bone cancer, but heavily regulated


  • Reduce risk of cardiovascular disease in people with high blood cholesterol
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Recreational Drugs

Recreational drugs are used for the effecr rather than for medical purposes. Taking soft drugs could lead to use of harder drugs, perhaps because they have got used to the effect and want a 'hit' again

Legal drugs:
Overall impact of legal drugs is much more as more people misuse them than who take illegal drugs- there will be more who suffer harm from legal drugs. 

  • Alcohol
    Ethanol is a depressant (slows down nerve signals)
    Misuse can lead to damage to the liver (could develop into cirrhosis) and brain
  • Nicotine
    Nicotine is addictive
    Carbon monoxide combines with haemoglobin in red blood cells so reduces amount of oxygen in the blood - strain on circulatory system: heart disease, stroke
    Use during pregnancy can lead to miscarriage, low birth weight and premature birth
    Tar is a carcinogen: lung, mouth and throat cancer

Illegal drugs:

  • Ecstasy
  • Cannabis
  • Heroin
    (all can harm the heart and circulatory system)
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Cannabis and addiction



  • Calming and relaxing
  • Improves sleep
  • Releases dopamine
  • Increases sensations induced by colour and music


  • Links between use & long term mental illness
  • 75% people with psychosis have smoked cannabis
  • 18% - 30% schizophrenic cases linked with cannabis
  • Regular user has a 1 in 10 chance of psychosis


  • Addictive drugs like heroin and cocaine change chemical processes in the body
  • Make the person dependent on taking the drug
    Need more to have the same effect
  • Suffer withdrawal symptoms when stop taking the drug e.g. vomiting, cramping, depression, anxiety, irritability
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Drugs in sport

Some drugs affect sporting performance:

  • Steroids: increases muscle mass and strength, promotes muscle building and enables athletes to train harder
  • Stimulants: masks fatigue, increases rate of body functions, such as heart rate: can release energy more quickly
  • Analgesics: masks pain and fatigue
  • Diuretics: hides other drug use, helps to lose weight rapidly to reach a set limit

Ethical implications:

  • Use of drugs to improve sport performance is considered unethical
  • All drugs that affect performance (prescribed, legal, or not) are banned by sports competition regulations
  • Side effects of these drugs can harm the athletes
  • Drugs may give an unfair advantage over athletes who don't use them
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