Biology - Medical and Recreational Drugs

Some revision cards on the topic '11.3 - How do we use/abuse medical and recreational drugs?' 

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Drug discovery

When a new drug is made, it needs to be:

Effective - It must make you better by curing/preventing the aimed illness. 

Safe - It cannot be poisonous, and no bad side effects

Stable - Can take it under normal conditions and is storable.

Absorb and remove - Must help what is needed and then be able to be got rid of once it has done its work.  

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Development of new drugs

In a clinical trail, only half the patients are given the real drug treatment. The other patients are given a placebo - a dummy pill which contains no drug. The group who take the placebo are known as a control group

Why is a control group set up?

- As a comparison so you can observe the effects of the drug. 

The patients do not know which treatment they are getting - the placebo and real drug look EXACTLY ALIKE. The doctors are not told either so it does not affect the reactions or responses of the patients/doctors. 

It takes about 10 years for a new drug to be developed. 

New drugs are tested on human volunteers to make sure there are no side effects and that the drug actually works on humans. 

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Drug development Order

Researchers target a disease and develop ideas for treatments.

The search for possible drugs includes computer design of molecules and screening of hundreds of thousands of chemicals. 

Possible drugs are made (synthesised) in the lab.

In vitro screening - the potential medicines are tested on some cells in a lab. If cell dies, it'll be toxic.

Animal testing - small number of chemicals tested in animals. Find out how chemicals work in living organism. Find out side affects

Chemical testing on some healthy voluntarily humans.

Human Phase 2 trails testing on pateints suffering from disease.

Human phase 2 continues with larger number of patients. 

When medicine has passed all tests set down in law, granted a licence. Now doctors can use it to treat the target illness.

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Thalidomide was a sleeping drug developed in the 1950s. Doctors gave it to pregnant women during pregnancy to get rid of morning sickness - Thalidomide had been tested on animals so they thought it would be safe BUT they did not test pregnant animals. 

Women who had taken Thalidomide gave birth to babies with severe limb deformities.

Recently it has been found that thalidomide is useful for treating leprosy

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Cigarettes contain three dangerous substances:

  • Tar
  • Nicotine
  • Carbon Monoxide 

Tar - is a sticky black chemical which contains over 4000 chemicals; turns the lungs grey; is a carcinogen and clogs the lungs.

Nicotine - Is addictive so makes it hard to give up cigarettes.

Carbon monoxide - Lowers the oxygen uptake by red blood cells; is a poisons gas; and is absorbed by the red blood cells and takes the oxygen's place.

Diseases linked with smoking include:

  • Heart disease
  • Lung infections 
  • Caner 
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Cilia cells (which are fine hair-like substances which pushes the mucus out of the windpipe) line the trachea, but when you smoke the cilia gets paralysed so it cannot move the mucus out of the throat.

This is why smokers sometimes develop a smokers-cough, trying to cough the mucus out of the throat as the cilia cannot do it itself. 

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Types of Drugs

Stimulants e.g. Nicotine, caffeine, speed. 

  • Speeds up the action of the nervous system to make you feel more awake, alive, alert.

Depressants e.g. Alcohol 

  • Slow down the nervous system so you feel drowsy and calm.

Hallucinogens e.g. LSD

  • Alter the patterns in the brain giving unusual sensations and sometimes hallucinations.

Analgesics e.g. Painkillers, asprin

Narcotic e.g. Heroin

  • Work like painkillers, make you feel very drowsy as well as euphoric 
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Words associated with drugs

Tolerance – this is where the body gets used to the drug and more than usual has to be taken to get the same effect.

Addiction – this is where a person becomes dependent on a drug and they can’t go on without it.

Withdrawal Symptoms – this is when a person stops taking a drug because they have become addicted to it, and they suffer from withdrawal symptoms. They can be worse the harder the drug the person is stopping to take for example Heroin. 

Withdrawal symptoms include

  • Muscle tremors
  • Abdominal pains
  • Sweating

Rehabilitation – withdrawal symptoms can fade if the drug isn’t taken for 2-3 weeks of rehabilitation. (i.e. restoring to health) 

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