Medicines and Drugs Option D Part 1

What is a drug? What is a medicine? What is the difference between a drug and a medicine? What is a pharmaceutical? List different types of medicines. How are new drugs developed?

Pharmaceutical products A medicine or drug is any chemical that does one or more of the following to the human body: alters its physiological state (=how it functions), including consciousness, activity level or coordination alters incoming sensory sensations alters mood or emotions

Stages in development of a drug Identify disease, could be new disease. Identify target e.g. gene or enzyme which is necessary for disease to progress. Identify ‘lead’ molecule which can act on gene/enzyme in the disease organism or host and isolate or manufacture it. May need to be modified. Preclinical trials: testing of ‘lead molecule’ in laboratory, ‘in vitro’: the lead molecule is tested on animal/human cells and tissues which have been removed from the body and are kept in an artificial environment. ‘in vivo’: testing in live animals (usually 3 different species) to establish LD50 which is the amount which kills 50 % of animal population.

Stages in development of drug Clinical trials: on humans!! Testing of its effectiveness and dose range on humans using the placebo effect. This is a ‘blind trial’ in which half of the people/patients involved are given the drug whilst the other half are given a similar substance which is not the drug but none of the patients or even administrators know which half they are in. All patients should/could experience placebo. Structural modifications likely to be made to, for instance, improve effectiveness or reduce side-effects. Submission of reports on drug and its trials to regulatory bodies. Monitoring of the drug after it has been launched; molecule might need further structural changes; new side-effects e.g. thalidomide. Today, thalidomide is sold by Celgene, mainly as a treatment of certain cancers (multiple myeloma) and of a complication of leprosy. Thalidomide was first marketed in 1957 in West Germany under the trade-name Contergan. The German drug company Chemie Grünenthal developed and sold the drug. Primarily prescribed as a sedative or hypnotic, thalidomide also claimed to cure “anxiety, insomnia, gastritis, and tension".[3] Afterwards, it was used against nausea and to alleviate morning sickness in pregnant women. Thalidomide became an over-the-counter drug in West Germany on October 1, 1957. Shortly after the drug was sold in West Germany, between 5,000 and 7,000 infants were born withphocomelia (malformation of the limbs). Only 40% of these children survived.[4] Throughout the world, about 10,000 cases were reported of infants with phocomelia due to thalidomide; only 50% of the 10,000 survived. Those subjected to thalidomide while in the womb experienced limb deficiencies in a way that the long limbs either were not developed or presented themselves as stumps. Other effects included deformed eyes and hearts, deformed alimentary and urinary tracts, blindness and deafness.[5] The negative effects of thalidomide led to the development of more structured drug regulations and control over drug use and development.[6]

Placebo effect Occurs when a person experiences a positive therapeutic effect because they believe they have been given a drug although the substance given in reality is not a medicine but a ‘placebo’. Administered; the human body is fooled into healing itself. Often occurs with pain. How would you allow for the placebo effect when carrying out clinical trials? How would you analyze the results of clinical trials and make them reliable?

Name different ways in which drugs are administered? Why are drugs administered in a particular way?

Administering drugs (1) Oral: taken in by the mouth e.g. tablets, syrups, capsules - advantages and disadvantages? Parenteral - by injection: for fast delivery !!! intravenous: into a vein of the blood stream – used for immediate impacts as its fastest method; drug is immediately pumped around the body by the blood, e.g. anaesthetic. intramuscular i.e. into the muscles, e.g. many vaccines, antibiotics, usually used when a large dose needs to be administered. subcutaneous: in the layer of the skin directly below the cutis (dermis and epidermis) e.g. dental injections, morphine, insulin. Slow absorption and effect.

parenteral administration

oral Advantages Disadvantages Easily taken No specialist equipment needed Can be destroyed by stomach acid Slow to have an effect Can cause stomach bleeding or vomiting Only small amount of drug is absorbed Patient needs to be conscious Kids????

Administering drugs (2) Inhalation: e.g. medication for respiratory conditions such as asthma. Rectal: inserted into the rectum e.g. treatment for digestive illnesses, drug absorbed into the blood stream. Skin patches: e.g. hormone treatments. Topical, on the skin and in eyes/ears e.g. creams, eye drops

Discuss the following terms dosing regime tolerance therapeutic effect side-effects therapeutic window

Terms Dosing regime = the amount of drug used for each dose i.e. how much drug should be taken (amount + frequency) to obtain desired therapeutic effect. Tolerance Tolerance refers to the body’s reduced response to a drug i.e. its therapeutic effect is less than what it is intended, usually as a result of taking the drug over a long period of time. As a result more of the drug needs to be taken to achieve the same initial physiological effect with the danger of exceeding the lethal dose.

therapeutic window (1) The therapeutic window is the range of dosage over which a drug can be safely administered to a typical population. It is the range in concentration in the blood within which an administered drug must remain. The therapeutic window has a lowest and highest level. The lowest level of concentration is called the effective or therapeutic level or ED50; below this level the drug loses its therapeutic effect. The highest level is the toxic or LD50 level (= the dose needed to kill 50 % of (animal) population) above which adverse side-effects can occur.

therapeutic window (2) wide therapeutic window small effective dose (ED50) and larger lethal dose (LD50) as a result there is a big difference between effective and lethal dose. narrow therapeutic window small difference between effective and lethal dose usually because lethal dose is small.

Side effects Side-effects = physiological effects which are not intended and therefore undesired (intended = therapeutic effects); these could be: beneficial e.g. protect against heart disease. benign e.g. causing drowsiness, nausea constipation. adverse i.e. causing damage to other organs.