D1: Pharmaceutical drugs
D.1.1 List the effects of medicines and drugs on the functioning of the body. Drug or medicine is a substance that does one or more of the following:
Alters physiological state – consciousness, activity level, coordination Alters incoming sensory experience
Alters mood or emotion
The active ingredients in drugs and medicines can be isolated from a plants and animals or synthesized artificially.
Drugs supposed to assist human body’s natural self-healing capabilities.
Placebos are drugs containing no active ingredient, which “fool” the human body into healing.
D.1.2 Outline the stages involved in the research, development and testing of new pharmaceutical products. The research and development of new medicines is a long and costly process. It usually takes up to 12 years and costs more than $200 million.
1. First the drug must be isolated or synthetized. 2. The drug is tested on animals. LD50 and ED50 are determined. 3. The drug moves to Clinical Trials
a. Human Pharmacology – testing on small group of healthy volunteers for safety b. Therapeutic Exploratory – evaluates drug’s efficiency and side effects c. Confirmatory Stage – large-scale testing of drug 4. A local drug regulatory agency approves a medicine and decides whether it will be 5. OTC (over the counter) or on prescription only.
LD50 is a lethal dose necessary to kill 50 percent of animal population. ED50 is an effective dose, one creating a noticeable effect in 50% of animal population. The ratio between LD50 and ED50 is called the Therapeutic Index.
Therapeutic Index = LD50 / ED50
Therapeutic determines a safety of drug. If the therapeutic index of a drug is 10, a person would have to intake ten times more drug than the effective dose for the effects to be lethal. According to the therapeutic index, the researchers decide whether a dosage must be controlled. If TI is low, the dosage must be closely controlled.
During testing, half of the patients receive a real drug and the other half similar-looking placebo. This determined whether the drug has a real effect or the pill only fooled body into healing.
NOTE: We must know Thalidomide as an example of what can go wrong during R&D process of a drug. Thalidomide alleviates morning sickness during pregnancy. The drug’s development revealed severe side effects – babies, whose mothers used the medicine, got born with deformed limbs.
D.1.3 Describe the different methods of administering drugs. There are five ways of administering a drug:
a. Intravenous – veins
b. Intramuscular – muscles
c. Subcutaneous – under skin
2. Orally – mouth
3. Rectally – anus
4. By inhalation
5. Topically – on the skin (ointments, creams, …)
D.1.4 Discuss the terms therapeutic window, tolerance and side-effects. Therapeutic window – the difference between the effective dose and lethal dose; also called therapeutic index Side effects – the undesired effects of drugs
Ex: aspirin thins the blood (used as an anti-clotting agent to prevent a hearth attack) Morphium, the pain reliever, causes constipation.
Tolerance – a person taking a drug often gets used to the active ingredient, so it takes larger and larger doses to obtain the drug’s desired effect. There is a danger that a body would create a physical addiction to a drug. For instance, an addiction to caffeine: if the addict does not get his/her coffee, he/she gets headaches. Another issue is that with increasing dose, the user is coming closer and closer to the lethal dose.
Risk-to-benefit ratio – determines whether the side effects (risk) of the drug are acceptable in relation to its curing effects; for example, a drug curing baneful disease would be accepted despite high risks
D.2.1 State and explain how excess acidity in the...
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