Developing drugs

• In the 1700s, people were dying of a disease named dropsy which is the old name for the swelling (odema) that occurs when the circulation is failing. Dropsy causes a slow death as organs eventually fill with fluid
• William Withering observed a patient recovery after having a thermal remedy that contained foxglove. Digitalis is a chemical found in foxgloves that has been used as poison for centuries. However, by using trial and error with a range of concentrations, Withering found the correct dosage
• Because Withering was using trial and error to test for the correct dosage of digitalis, some patients died of drops as their concentration was not strong enough and others died of digitalis poisoning because their concentration was too high
• With the correct dosage, Witherinf made digitalis soup as a remedy for dropsy. Doctors are still using the toxin, now called digoxin, to this day
• Digitalis works by increasing the strength of heart contractions so blood can be pumped around the body more efficiently
• A new medicine has to be:

  • effective
  • safe
  • stable
  • easily taken into/removed from the body
  • can be made on a large scale
• When scientists think they have a compound that might make a useful medicine, they patent it. A patent gives the inventor the right to be the only one to make and sell their invention.
• Potential new drugs must be developed following strict criteria to be used internationally. The new compound is first tests on cell cultures, tissue cultures, and whole organs in the lap so scientists can see if the compound does what they thought it would do
• To determine a good delivery system for the drug, the potential drug is tested on animals to see how it works on a whole organism and to check its safety and effectiveness
• Mammals are used with similar physiological systems to humans like rats and mice. Some tests must be carried out on at least two species, one rodent and one non-rodent.
• Animal testing is very expensive and time-consuming and is the centre of many ethical debates. The numbers of animals used are kept to a minimum and the tests are as refined as possible to create the minimum of distress.
• The use of rats and mice is perceived as less emotive than other animals. The rodents will also provide valid models and they are small and easy to keep in humans conditions
• If the animal testing has been successful, the very first human trials take place. Sme of the patients will be given a placebo. A placebo is a control and helps to remove the possibility that people, are feeling better just because they think they are getting a new drug
• Clinical trials happen in 3 phases

  • phase 1 - small number of healthy volunteers. This is to check the drug works as expected ans doesn’t cause any side effects
  • phase 2 - larger number but patients with the condition. Some are given a drug and some are given a placebo. This van show scientists how the medicine affects the disease in patients and if there are side effects.
  • phase 3 - large scale group size. It is a comparison to see if this drug works better than existing drugs, and if it is safe
• A large group size can be used to increase reliability
• Phase 2 and 3 trials are normally carried out as double-blind trials. This means neither the doctor or scientist whether the patient is receiving new medicine, a control medicine or a placebo
• Patients often seem like they respond to a treatment because they believe that it will do them good. This response is called the placebo effect. The double-blind trial will measure this
• Drug trials can sometimes be unethical, as sometimes a placebo drug is tested on some with the condition
• Sometimes patients may stop taking the drug for various reasons making the results invalid