Option D1: Pharmaceutical products

D.1.1 List the effects of medicines and drugs on the functioning of the body

The terms medicine and drugs are sometimes used interchangeably and sometimes have slightly different meanings in different parts of the world. They are most clearly defined as follows

Drugs are chemicals that affects how the body works. This includes changes for the better or the worse. The term is associated with substances which are illegal in many countries, such as cocaine, ecstasy and heroin.

Medicines are substances that improves health. Medicine, which may be natural or synthetic, therefore contain beneficial drugs. Synthetic medicines also contain other ingredients, which are non-active but help in the presentation and administration of the drug. The beneficial effect of a medicine is known as its therapeutic effect.

In general, the effects on the body of drugs include the following:

• alteration of the physiological state, including consciousness, activity level and coordination
• alteration of incoming sensory sensations
• alteration of mood or emotions

D.1.2 Outline the stages involved in the research, development and testing of new pharmaceutical products

Pharmaceutical groups and research groups are constantly developing new drugs in response to the new diseases. The goal is usually to develop drugs that are more effective and have fewer toxic side-effects than pre-exisiting drugs for the same conditions, as well as drugs for new conditions such as SARS. The stages are split into 3 main stages: research, development and regulatory review.

Discovery Research

First stage in drug development involves identifying and extracting compounds that have been shown to have biological activity and are known as lead compounds. Lead compounds are often derived from plants.

Next, the effectiveness of lead compound is optimized by making and testing many chemically related compounds known as analogues. This process is often now fast-tracked by two relatively new techniques: combinatorial chemistry and high-throughput screening. Following extensive laboratory tests, a potenial medicine is then tested on animals, under strict legislative control.

Development research

There are usually three phases in subsequent human trials involving an increasing number of patients. The effectiveness of the drug is judged by the relative improvement in the patients who have received the real medication compared with those on a placebo in phase III.

Phase I - 50-100 healthy volunteer
Phase II - 200-400 patients
Phase III - 3000+ patients: half are given the drug under test, the other half a placebo; neither the doctor nor the patient knows which preparation is being given

Regulatory review

Regulators realized then that it was not sufficient only to establish the safety and effectiveness of a drug before it went on the market. An additional system was needed to track medications once the population had access to them, when effects in different groups of people, including long-term effects, become known.

D.1.3 Describe the different methods of administering drugs

The manner in which a drug is delivered to the patient's body depends on many factors. These include the chemical nature of the drug, the condition of the patient and the most effective way of getting the drug to the target organ.

Oral

This method is the most common example of medicine. Examples include tablets, capsules, pills and liquids.

Inhalation

This method of administration is done through vapour breathed in or smoking. Examples include medications for respiratory conditions such as asthma.

Skin patches

This method of administration is absorbed directly from the skin into the blood. Examples includes some hormone treatments like estrogen and nicotine patches

Suppositories

This method of administration is inserted into the rectum. It is used for treatment of digestive illness. Examples include hemorrhoids.

Eye or ear drops

This method of administration are liquids delivered directly to the opening. This is used for treatments of infection of the eye or ear.

Parenteral - by injection

There are three different methods of administration through injection. By intramuscular, intravenous or subcutaneous injection.

D.1.4 Discuss the terms therapeutic window, tolerance and side-effects

The dosing regime for a drug refers to the amount of drug used for each dose and the frequency of administration. Determining this is usually quite difficult as there are so many variable involved - for example the age, sex and weight of the patient, as well as factors such as diet and environment. The important thing is that the concentration in the blood stream must remain within a certain range: above this range, unacceptable side-effects may occur; below this range and there may not be effective therapeutic outcomes. This target range is referred to as the therapeutic window.

When a person is given repeated doses of a drug, it sometimes happens that tolerance develops, that is a reduced response to the drug. So higher doses are needed to produce the same effect and this increases the chances of there being toxic side-effects.

Side-effects are defined as physiological effects which are not intended and vary greatly from one drug to another, and with the same drug in different people. Sometimes side-effects may be beneficial, such as the fact that aspirin, taken for pain relief, helps protect against heart disease. Other times, the side-effects may be relatively benign, such as causing drowsiness, nausea or constipation.