McKenna's Pharmacology for Nursing, 2e

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P A R T 6  Drugs acting on the endocrine system

Drug therapy across the lifespan

BOX 38.1

Hypoglycaemic agents CHILDREN

GI tract. GLP-1 has a very short half-life and is metabo- lised by the enzyme dipeptidyl-peptidase-4 (DPP-4) . Insulin circulates through the body and reacts with specific insulin receptor sites to stimulate the transport of glucose into the cells to be used for energy, a process called facilitated diffusion. Insulin also stimulates the synthesis of glycogen (glucose stored for immediate release during times of stress or low glucose), the conver- sion of lipids into fat stored in the form of adipose tissue and the synthesis of needed proteins from amino acids. Insulin is released after a meal, when the blood glucose levels rise. It circulates and affects metabolism, allowing the body to either store or use the nutrients from the meal effectively. As a result of the insulin reminders about diet, the need for exercise, skin and foot care, and warning signs to report to the healthcare provider. The older person is also more likely to experience end organ damage related to the diabetes—loss of vision, kidney problems, coronary artery disease, infections— and the drug regimen of these people can become quite complex. Careful screening for drug interactions is an important aspect of the assessment of these people. be asked specifically whether they use any of these agents and adjustments should be made accordingly. PREGNANCY AND BREASTFEEDING Insulin therapy is the best choice for women with diabetes mellitus during pregnancy and breastfeeding, which are times of high stress and metabolic demands. Needs may change on a daily basis, and the mother should have ready support and extensive teaching about what to do if hypoglycaemia or hyperglycaemia occurs.The period of labour and birth is often a critical time in diabetes management because of the stress and sudden changes in body fluid volume and hormone levels.The obstetrician and the endocrinologist or primary care provider should consult frequently about the best way to support the woman through this period. OLDER ADULTS Older adults can have many underlying problems that complicate diabetes management. Poor vision and/or coordination may make it difficult to prepare a syringe. A week’s supply of syringes can be prepared and refrigerated for the usual dose of insulin. Dietary deficiencies related to changes in taste, absorption or attitude may lead to wide fluctuations in blood sugar levels, making it difficult to control diabetes. Many areas have nutritional assistance programs for older adults (e.g. Meals onWheels) or have places that can refer people to appropriate agencies that might be able to offer assistance. Older adults have a greater incidence of renal or hepatic impairment, and kidney and liver function should be evaluated before starting any of these drugs. Combinations of oral agents may not be feasible with severe dysfunction and the person may need to use insulin to control blood glucose levels. Older adults should receive periodic educational

Insulin Insulin is the hormone produced by the pancreatic beta cells of the islets of Langerhans. The hormone is released into circulation when the levels of glucose around these cells rise. It is also released in response to incre- tins , peptides that are produced in the gastrointestinal (GI) tract in response to food. One of these incretins, glucagon-like polypeptide-1 (GLP-1) , increases insulin release and decreases glucagon release (in preparation for the nutrients that will soon be absorbed). GLP-1 also slows GI emptying to allow more absorption of nutrients and stimulates the satiety centre in the hypothalamus to decrease the desire to eat because food is already in the Treatment of diabetes in children is a difficult challenge of balancing diet, activity, growth, stressors and insulin requirements. Children need to be carefully monitored for any sign of hypoglycaemia or hyperglycaemia and treated quickly because their fast metabolism and lack of body reserves can push them into a severe state quickly. Insulin dose, especially in infants, may be so small that it is difficult to calibrate. Insulin often needs to be diluted to a volume that can be detected on the syringe. A second person should always check the calculations and dose of insulin being given to small children. Teenagers often present a real challenge for diabetes management.The desire to be “normal” often leads to a resistance to dietary restrictions and insulin injections. The metabolism of the teenager is also in flux, leading to complications in regulating insulin dose. A team approach, including the child, family members, teachers, coaches, and even friends, may be the best way to help the child deal with the disease and the required therapy. New delivery methods for insulin may help this age group cope with the drug therapy in the future. Metformin is the only oral hypoglycaemic drug approved for children. It has established dosing for children 10 years of age and older. With the increasing number of children being diagnosed with type 2 diabetes, the use of other agents in children is being tested. ADULTS Adults need extensive education about the disease, as well as about the drug therapy. Warning signs and symptoms should be stressed repeatedly as the adult learns to juggle insulin needs with exercise, stressors, other drug effects and diet. Adults maintained on oral agents need to be monitored for changes in response to the drugs. Often additional drugs are added or doses are changed as the disease progresses over time. Exercise and diet should always be emphasised as the mainstay of dealing with diabetes. Adults need to be cautioned about the use of over-the-counter and herbal or alternative therapies. Many of these products contain agents that alter blood glucose levels and will change insulin or oral agent requirements. Adults should always