Emirates International School
Grade 13
Drugs and medicines (Pharmaceutical products)
Name:…………………………………………………. Date:………………………………………
1.
. a.
List the e ff ects of medicines and drugs on the functioning of the body.
A drug or medicine is any chemical which does one or more of the following: alters incoming sensory sensations, alters mood or emotions, alters physiological state, including consciousness, activity level or co-ordination.
b.
State what a placebo is and describe the placebo e ff ect.
A placebo is an inert substance used as a control in an experiment, or given to patients for its probable beneficial effects (i.e. a ‘fake’ therapy without any side effects). The placebo effect refers to a pharmacologically inert substance that produces a significant reaction because of what an individual expects, desires or is told will happen.
c.
Outline the stages involved in testing a new drug.
The testing of new drugs is a lengthy process and the stages involved usually include: tests on microbes or tissue cultures, animal tests to establish the LD50 (the dose lethal to half the population) and double-blind clinical trials.
d.
Outline four methods of drug administration and state their relative advantage and disadvantage.
Orally: by mouth; very convenient. However the effect is variable since the rate of absorption is influenced by drug concentration and stomach content.
Parenteral (by injection):
(i) Beneath the skin (subcutaneous route): Drug absorption is slower than intravenous
(directly into a vein)
(ii) into muscles (intra-muscular): This method is used if immediate response is not

Emirates International School
Grade 13
Drugs and medicines (Pharmaceutical products)
Name:…………………………………………………. Date:……………………………………… required or when a large volume of drug needs to be injected. The method is relatively safe and easy provided a blood vessel is not accidentally penetrated
(iii) directly into the blood stream (intravenous): the drug is introduced by injection into a vein and distributed around the body within about a minute, so the effect is virtually instantaneous. An advantage is that it is possible to administer precise amounts of drug since concentration is not affected by stomach acid or content.
However, once administered, the drug cannot be retrieved as it can be (to some extent) with oral administration. Inhalation (by breathing in): administration is rapid because of the extensive network of blood vessels in the lungs.
Rectal (via the rectum): is very effective when patients experience nausea or vomiting or are unable to take medicine orally before or after surgery. Drugs that are pH sensitive and which may be destroyed by the stomach’s acidity may be delivered rectally.
2.
. a.
Discuss the terms therapeutic window, tolerance, and side effects.
Therapeutic window is a measure of the relative margin of safety of the drug for a particular treatment (for a typical population). Quantitatively, it is given as a ratio of the lethal dose (LD50) to the therapeutic dose of the drug (ED50) where LD50 is the lethal dose for 50% of the population and ED50 is the effective dose for 50% of the population.
Tolerance means that, over time and with regular use, a user needs increasing

Emirates International School
Grade 13
Drugs and medicines (Pharmaceutical products)
Name:…………………………………………………. Date:……………………………………… amounts of a drug to get the same physiological effect. Tolerance increases the health hazards of any drug simply because the amount taken increases over time.
Side effects refer to the unwanted responses to a drug are considered side effects b.
Distinguish between physical and psychological dependence.
Physical dependence occurs when a drug user’s body becomes so accustomed to a drug that it can only function normally if the drug is present. Without the drug, the user may experience a variety of physical symptoms ranging from mild discomfort to convulsions.
Psychological dependence exists when a drug is so central to a person’s thoughts, emotions, and activities that it is extremely difficult to stop using it, or even stop thinking about it. Psychological dependence is marked by an intense craving for the drug and its effects. Like physical dependence, psychological dependence is a form of drug addiction.