Medicine and Drugs Revision

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What is a drug?

Drug - substance that alters way body works.

  • can affect mind, body or both
  • some used for pleasure/recreation, some for medicines

Scientists continually developing new drugs - has to be tested & trialled

Good medicine is -

Effective - must prevent/cure disease aimed at

Safe - must not be toxic & have no unacceptable side effects

Stable - must be able to use under normal conditions & store for some time

Excreted safely from body - must be able to reach target area of body & break down safely & excreted (removed from body)

  • testing new medicine is v.expensive
  • new drugs must be extensively tested & trialled before use
  • tested in series of stages ot find out if safe & effective
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Main stages in testing a new drug

1) Researchers target particular disease

2) Researchers screen hundreds of thousands of chemicals (computer models)

3) Possible drugs made from most successful chemical compounds

4) Potential medicines tested on isolated cells & tissue cultures in lab. In vitro testing

5) Small no. of chemicals that make it this far - tested on animals - find out how they work on whole organisms. Tells us what dose could be used & any possible side effects

6) Animal testing continues lloking at long term effects of medicine

7) Phase 1 - Clinical trials. Smal no. of healthy volunteers used - safety of medicine in humans  

8) Phase 2 - Small no. of patients suffering from disease - if safe & effective

9) Phase 3 - Large no. of patients used & progress monitored

10) Medicine granted licence & doctors can now use to treat patients

11) Phase 4 - Medicine monitored to make sure safe

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Double Blind Trials

Double Blind Trials

  • used to see how effective medicine is
  • patients with target disease agree to take part in trials
  • either given placebo that does not contain active drug, or new medicine with active drug
  • neither doctor or patient knows who has recieved placebo/real drug until after trials
  • patient's health monitored carefully

Placebo - has no effect.  Used as a control in testing new drugs.

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Thalidomide

Thalidomide

  • drug developed as sleeping pill
  • tested in medical drugs trials using rats & no bad effects found
  • found to be beneficial in relieving morning sickness in pregnant women
  • not fully tested for this treatment
  • tested on rabbits & monkeys - no birth defects
  • many babies born with severe abnormalities in arms &/or legs completely missing etc.
  • banned for all uses.
  • later used for treating leprosy in developing world - WHO now banned it
  • had NOT been tested on pregnant women

WHO - World Health Organisation

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Statins

Statins

  • chemicals found in plants - used to reduce cholesterol levels
  • block certain enzyme in liver needed to make cholesterol
  • level of cholesterol in blood considered healthy - 4mmols/l
  • 2 out of 3 people in UK have level above this
  • lowers risk of heart attacks by 25-40%
  • few side effects
  • difficult to become pregnant while on them
  • have to be taken for life
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Misuse of drugs (drug abuse)

Soft drugs - less damaging drugs

Hard drugs - more damaging drugs

Legal, recreational drugs - alcohol, nicotine & caffeine

Ilegal drugs - heroin, cocaine, cannabis & ecstasy

Alcohol - damages liver & kidneys, slows body responses, slurred speech - heart problems, hangover

Nicotine - relaxation - addiction, heart disease

Heroin, cocaine, cannabis & ecstasy - addiction, dependence, heart & circulatory problems

  • drugs change chemical processes in body - cause addiction
  • withdrawal symptoms without them - severe aches & pains, sweating, headaches, shaking & craving for drug
  • cocaine & heroin very addictive
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Impact of drugs on health

Recreational drugs - used for pleasure, affect nervous system

  • particularly affect brain
  • caffeine, amphetamines, cocaine - speed up nerous system - more energetic & alert - stimulants
  • cannabis, nicotine & alcohol - slow down responses of brain - depressants
  • impact of legal drugs greater than illegal drugs - more people take them
  • prescribed & non-prescribed - non prescribed more dangerous
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Cannabis

Cannabis

  • illegal drug
  • cannabis smoke contains chemicals - causes mental illness in some people
  • can be seen as a gateway drug
  • less dangerous then alcohol
  • effects not too serious

Gateway drug - drug making easier for person to begin taking 'harder' drugs through contact with drug dealers

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Performance Enhancing Drugs

  • athletes use to enhance performance - several types of drug
  • some banned, some legally availble on prescription
  • ALL banned by sporting regulations

Stimulants

  • boost bodily functions e.g. inc. heart rate
  • leads to more oxygen delivered to muscles, more respiration
  • more energy produced for muscle contraction - unfair advantage

Anabolic Steriods

  • man-made chemicals similar to male sex hormone testosterone
  • inc. size & strength of muscles during training - unfair advantage
  • harmful effects - irritability & sudden rages (changes in behaviour), hair loss, acne & severe damage to heart, liver & kidneys

Legal - lots of training to inc. no. of red blood cells.  Ilegal to buy hormone that produces more red blood cells.

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Important Definitions

Bias - when person has interest in outcome of experiment/trial that will bring them some gain.

Recreational drug - drugs taken for pleasure.

Class A - worst illegal drugs.

Class B - second worse illegal drugs.

Class C - illegal drugs but only just illegal.

Placebo - doesn't contain active drug, no effect.  Used as a control in testing new medicine.

Double Blind - both doctors & patients don't know which is placebo/new medicine until after trials.

Addiction - dependant on particular substance.  Change in chemical processes of body & withdrawal symptoms suffered without substance.

Gateway drug - drug making easier for person to begin taking 'harder' drugs through contact with drug dealers.

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