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Therapeutic Effects SAMPLE both natural both natura compounds) and mpounds) and been used as medicines for been used as medicines for today, plants are an important source plants are an important source eveloped into drugs. For example, ed into drugs. For example, Digitalis purpurea purpurea (foxglove plant) iac disorders; opiates such as morphine, ates such as morphine, averine from averine fro Papaver somniferum somniferum (opium he taxanes derived from the bark of e taxanes derived from the bark ofTaxus brev- Taxus trees) are used in cancer chemotherapy. Plant rees) are used in cancer chemotherapy. Pla extracts have also become the main component of the grow- also become the main component of the growalternative therapy movement. therapy movement. Fungi The most well-known example of a drug The most well-known example fungi is the antibiotic penicillin used to fungi is the antibiotic penicillin of communicable diseases. Penicillin of communicable diseases. Penici antibiotics are derived from th antibiotics are derived from t chrysogenum . The immunosupp . The immunosup used to reduce the activity o used to reduce the activ following organ transplantation, organ transplantation, from a fungus. fungus. Animal Products oducSAMPLE tering Escherichia coli bacteria, making insulin bacteria, making insu some of the impurities that come with anima some of the impurities that come with anim The insulin produced using genetic engineering is known as a biopharmaceutical , a protei , a prote prepared using genetic engineering technology. Inorganic Compounds Salts of various elements can Salts of variou the human body. Aluminiu e human body even gold are used to tre even gold are used of these elements w when a cause–effe when a cause–eff shows example shows exam peutic benefi peutic bene Synt E SAMPLE gastric acidity hyperphosphataemia the formation of phosphate Prevention of dental cavities of osteoporosis rheumatoid arthritis defi ciency anaemia 6 PART I — Introduction to Nursing Pharmacology Drug Evaluation To become a drug, a chemical must have demonstrated therapeutic value or effi cacy without severe toxicity or damaging properties. Once a chemical that might have therapeutic value is identifi ed, it must undergo a series of tests to evaluate its actual therapeutic and toxic effects. The need for extensive testing was reinforced by the ‘thalidomide disaster’ in the early 1960s. The hypnotic drug thalidomide was regarded as suitable for use during pregnancy. However, the drug had not been tested on pregnant animals and was subsequently found to be a potent teratogen (i.e. causing adverse effects on the foetus). This resulted in more than 10,000 children born with severe malformations. This process of evaluation signifi cantly reduces the number of potential drugs that actually make it to the end stage: for every 5000 chemicals that are identifi ed as being potential drugs, only one will become an approved drug. Before receiving fi nal approval for marketing to the public, drugs must pass through preclinical tests on animals and phase I, II and III studies on humans. Figure 1.1 highlights the various phases of drug development. Preclinical Tests In preclinical tests , chemicals that may have therapeutic value are tested on cell cultures and laboratory animals. Whole animal testing is an important part of the drug development process; however, there is signifi cant public opposition to the use of animals in experiments. A comment often quoted is that the physiological processes animals undergo are so different from our own. Although there are recognized differences in the way humans and laboratory animals (e.g. rats, rabbits) metabolize drugs ( Berthou et al. , 1992 ) for example, these differences are far outweighed by the similarities between species (Research Defence Society, 2009). It should also be recognized that the number of experiments using live animals has decreased by over 35% in the past 30 years (Home Offi ce, 2009). Preclinical tests have several purposes: • To assess if they are likely to have benefi cial effects in models of disease. • To evaluate any toxic effects in the short and long term. • To assess their
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