Drug Synthesis Noadswood Science, 2016

Drug Synthesis Wednesday, May 16, 2018 To identify the steps followed in producing safe new drugs

Precise Learning Most new drugs are synthesised by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant. New medical drugs have to be tested and trialled before being used to check that they are safe and effective (understand that the results of testing and trials are published only after scrutiny by peer review) New drugs are extensively tested for toxicity, efficacy and dose. Preclinical testing is done in a laboratory using cells, tissues and live animals. Clinical trials use healthy volunteers and patients. Very low doses of the drug are given at the start of the clinical trial. If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug. In double blind trials, some patients are given a placebo.

Drug Testing New medical drugs have to be tested before they can be prescribed for patients They are tested in a laboratory to check that they are not toxic, and later they are trialled using human volunteers At this point, any potential side effects should show themselves – most substances do not pass all the tests and trials, so drug development is expensive and takes a long time *Medical drug trials are not without risk – sometimes very severe and unexpected side-effects appear

Medicine Development Complete the developing medicines worksheet

Medicine Development Researchers target a disease to develop treatment Computer models and chemicals are screened for their use as possible drugs Possible drugs are made in a lab Drugs are tested on cell cultures in a lab to make sure they are not toxic Animal testing takes place Trials on humans begin A licence to a drug and so doctors can prescribe them Drugs are monitored

Thalidomide Thalidomide is a drug that was prescribed during the late 1950s and early 1960s It was developed as a sleeping pill, but it was also thought to be useful for easing morning sickness in pregnant women – unfortunately, it had not been tested for use in this way

Thalidomide – Birth Defects By 1960, thalidomide was found to damage the development of unborn babies, especially if it had been taken in the first four to eight weeks of pregnancy The drug led to the arms or legs of the babies being very short or incompletely formed – more than 10,000 babies were affected around the world and as a result of this disaster, thalidomide was banned

Thalidomide – Modern Use Thalidomide is now used as a treatment for leprosy and bone cancer Its use is heavily regulated, however, to prevent a repeat of the problems it caused in the last century

Thalidomide

Developing Drugs Date Event Mid 1950s Animal testing using thalidomide was undertaken – tests showed that it was safe but the tests were “inadequate” (no tests were done on pregnant animals) Late 1950s Thalidomide prescribed to pregnant mothers to help sleep and morning sickness problems Early 1960s Babies are born with birth defects and the drug was banned worldwide – around 12,000 deformed Thalidomide babies born (4,000 die in first year) Late 1960s Tests show that Thalidomide can help leprosy sufferers and it is still used today for this purpose

Drug Trials Would you take part in a well paid drug trial? ‘Elephant man’ drug trial - unfortunately a drug designed to reduce the immune response actually increased it, resulting in the bodies of a variety of men who applied for a drug trial swelled up so much that one man’s girlfriend said he looked like ‘the elephant man’ The men were left fighting for their lives in hospital as their internal organs started to shut down – they all survived although the massive swelling affected the circulation to their fingers and toes (the worst affected now face amputation of their fingers and toes)

Animal Testing To prevent these types of problems, all medical drugs are tested extensively on animals and humans prior to use

Placebos To test how well a drug works patients are randomly put into two groups – one is given the new drug whilst the other is given a placebo (a substance that is like the drug being tested but actually doesn’t do anything) This way the researchers can see the actual difference the drug makes The placebo effect is when a patient expects the treatment to work so ‘feels better’, even though the treatment isn’t doing anything

Blind and Double-blind Trials Clinical trials are blind – the patient in the study does not know if they’re getting a drug or placebo Double-blind trials include both the patient and the doctor until results have been gathered – this way the doctor monitoring the patients and analysing the results doesn’t subconsciously influence the outcome Drugs testing results are not published until they have been peer reviewed to help prevent false claims

Drug Trials Write a short persuasive article on your views of drug testing and whether it should happen on both animals and humans Should we test drugs on just animals / just humans / both?! Should this testing be allowed for medicinal and cosmetic reasons?!

Practice Questions What are drugs tested on in preclinical testing? Give two things that drugs testing aims to find out In a clinical trial what type of volunteer is the drug tested on first Describe the dosage of a drug that is first used in a clinical trial What is a placebo? Explain what is involved in a double-blind trial

Answers What are drugs tested on in preclinical testing – human cells, tissues and animals Give two things that drugs testing aims to find out – does the drug work / what is the drug’s toxicity / optimum dosage In a clinical trial what type of volunteer is the drug tested on first – healthy volunteers Describe the dosage of a drug that is first used in a clinical trial – very low What is a placebo – substance like the drug which doesn’t do anything Explain what is involved in a double-blind trial – both the patient and the doctor are unaware if the drug or a placebo are being given