Option D.1 – Pharmaceutical Products

Option D.1 – Pharmaceutical Products

D.1.1 – List the effects of drugs and medicines

Drugs and medicines are chemicals that have the ability to alter the functioning of the body, including:

  • Incoming sensory sensation
  • Mood or emotions
  • Physiological state (consciousness, activity level or coordination)

In the case of medicine, these properties can be highly beneficial, allowing us to recover from injuries or disease better, or offer pain relief. The human body already has a number of natural healing processes in place, but in the case of more extreme injuries, drugs can help to accelerate these processes. However, drugs can still be harmful, especially in high doses.

The ‘placebo’ effect is when a person believes they are taking a drug with a particular function, but are not actually administered anything (instead, they will be given a sugar pill or other such treatment that has no effect). Interestingly, the psychological state of the patient can also accelerate their healing process, as the body’s natural healing processes take over. Placebos are often used as part of drug trials for testing their effectiveness and side-effects.

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

pharmaceutical products

Since many drugs have been found to have harmful or unpleasant side-effects, the process of research and development is crucial for ensuring that drugs are safe for human use before they are put on the market. This testing can take a long time and be very costly for businesses. Most governments have strict controls over which drugs can be made available to the public, since those without proper testing can pose serious threats to public health.

Many drugs have been discovered by researching plants that are known to have certain effects, then isolating the active ingredient. In the early stages of testing, the drug is given to cell cultures in a lab. If they are found to be safe, then research will look at the responses of animals, depending on regulations on animal testing. If any harmful side effects are found, then research will usually stop.

Drugs that are safe on animals will then go to trial on humans who volunteer. These people will be a combination of patients and non-patients. To ensure the validity of the test, some of the volunteers may be given a placebo as the control. Previously unknown side effects may become apparent at this stage.

If all this testing is successfully completed without any serious side effects being found, and the drug also achieves its intended purpose, then it will be put up for approval from the appropriate government body. This entire process can take years – sometimes decades – so there is a large time lag between the discovery of a drug and when the public are able to benefit from it. Businesses will also have to consider the potential profitability of a drug: will the sales of the drug eventually cover the research and development costs?

Thalidomide

This drug was marketed to pregnant women to help relieve morning sickness. Some countries allowed it to be sold without prescription, so that it was freely available and users were not monitored for side effects.

Once the children of mothers using the drug were born, it was revealed that the drug had the adverse side-effect of absent or deformed limbs in the child. Investigation found that these effects had been identified during trials before its release, but had chosen to hide these outcomes due to the profitability of the drug. Thalidomide was not withdrawn until 1961.

D.1.3 – Describe the different methods of administering drugs

Oral Methods

When taken this way, drugs are usually in the form of a tablet, capsule, powder or liquid. They are taken through the mouth, and then absorbed into the bloodstream from the digestive system. This is the most convenient method as it is portable, but the drugs take longer to be absorbed than through other methods.

Rectal Methods

Using this method, drugs are injected through the anus. This is usually used when the patient is suffering from nausea, vomiting or convulsions, and they need fast relief. Also, some patients, especially small children, may not swallow tablets. The drugs are absorbed through the large intestine and into the bloodstream.

Inhalation

Using this method, the patient breathes in the drugs and they are absorbed into the bloodstream through the lungs. The most common example of this ‘puffers’ used to treat asthma.

Injection

This is also called parenteral. Injections may be intravenous, intramuscular or subcutaneous.

Intravenous injection is when the drug is inserted directly into the bloodstream, giving it a more rapid effect. However, doing this accurately requires training. In subcutaneous injection, the drug is injected into the fatty tissue under the skin, which is common for dental injections. The drugs are not absorbed as quickly as for intravenous injections.

Intramuscular injection involves inserting the drug into muscles, a common method for giving vaccines or relieving severe allergic reactions.

Also, some drugs can be placed on the surface of the skin in the form of creams, ointments, sprays and drops, allowing their effect to be restricted to the affected area.

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

Therapeutic Window

The dosage of a drug that is required for fulfilling its purpose is called the effective dosage (ED50). The 50 means that the dosage would give the appropriate response in 50% of the population, which means that it would be too large or too small for the remaining 50%. Likewise, the dosage that would be large enough to kill 50% of the population is called the lethal dosage (LD50). Since any drug, even beneficial ones, are deadly in sufficiently high doses, it is important that patients are not at too high a risk of overdose from drugs they are being administered. The safety range of a drug can be found by calculating the therapeutic window.

If this window is large, then patients would have to take significantly more medicine than necessary before it reaches toxic levels. On the other hand, if someone is taking a drug with a very small therapeutic window, they are more likely to overdose and die because the lethal dose is very close to the effective dose. These drugs require greater care when they are being measured to ensure the safety of the patient.

Tolerance

When someone is tolerant of a drug, it means that their body has become used to the presence of it, reducing the effect of the same dose. As a result, the person must have higher doses to achieve the same purpose. This tends to occur after repeated use the receptors in the brain become accustomed to the presence of the drug, since it is frequently present in higher amounts. In some cases, the brain will change its own chemical balance of enzymes and other neurotransmitters. Often, the brain will secrete larger amounts of the enzymes that break down the drug, meaning that when the user takes the drug again, it would be broken down faster and the effect is reduced. Also, the brain may essentially ‘turn off’ the receptors for that drug.

Tolerance is dangerous because users feel the need to have higher doses, which can easily lead to overdose. Their tolerance level will steadily increase, until eventually they are at or near the LD50.

Side Effects

When people take drugs, it is for a specific purpose. Painkillers are typically taken to relieve pain that prevents the person’s normal functioning. This purpose is called the main effect. However, most drugs will produce more than one effect on the body, with the others being called side effects. While this can be useful because it makes a single drug have multiple purposes, many side effects are very unpleasant for the patient. In the case of the painkiller morphine, one of its side effects is constipation. If a person has diarrhoea, then the main effect of morphine changes, so that painkilling is a side effect. Evidently the difference between the main effect and side effects is relative to the situation of the user.

The side effects of some drugs are much more distressing or harmful than this, and sometimes they might outweigh the benefit of the main effect. When deciding to use certain drugs, it becomes necessary to consider the risk : benefit ratio. The example of Thalidomide mentioned earlier shows that, whilst the main effect was highly beneficial to the mothers, the risk of having deformed babies far outweighs they benefit of relief from morning sickness.