McKenna's Pharmacology for Nursing, 2e

591

C H A P T E R 3 8 Agents to control blood glucose levels

Therapeutic actions and indications These agents increase the blood glucose level by decreas- ing insulin release and accelerating the breakdown of glycogen in the liver to release glucose. They are indic­ ated for the treatment of hypoglycaemic reactions related to insulin or oral hypoglycaemic agents, for the treatment of hypoglycaemia related to pancreatic or other cancers and for short-term treatment of acute hypoglycaemia related to anterior pituitary dysfunction (Table 38.4). Pharmacokinetics Glucagon is given parenterally only and is the preferred agent for emergency situations. Glucagon is rapidly absorbed and widely distributed throughout the body. It is excreted in the urine. Contraindications and cautions There are no adequate studies on glucagon and preg- nancy, so use should be reserved for those situations in which the benefits to the mother outweigh any potential risks to the fetus. Caution should be used during breast- feeding because the drug may cause hyperglycaemic effects in the baby. Caution should be used in individu- als with renal or hepatic dysfunction or cardiovascular disease. Prototype summary: Glucagon Indications: Counteracts severe hypoglycaemic reactions in diabetic people treated with insulin. Actions: Accelerates the breakdown of glycogen to glucose in the liver, causing an increase in blood glucose levels. Pharmacokinetics: Route Onset Peak Duration IV 1 min 15 mins 9–20 mins T 1/2 : 3 to 10 minutes; metabolised in the liver and excreted in the urine and bile. Adverse effects: Hypotension, hypertension, nausea, vomiting, respiratory distress with hypersensitivity reactions, hypokalaemia with overdose.

■■ Sulfonylureas work only if the pancreas has functioning beta cells. ■■ Other oral hypoglycaemic agents work to slow GI absorption of glucose, increase release of insulin by beta cells, increase insulin-receptor-site sensitivity and/or block liver release of glucose. ■■ In times of severe stress, individuals regulated on other oral hypoglycaemic agents usually need to be switched to insulin to control blood glucose levels. ■■ Proper diet and exercise are the backbone of diabetes mellitus management; oral hypoglycaemic drugs are adjuncts to help control blood glucose levels. GLUCOSE-ELEVATING AGENTS Glucose-elevating agents, as the name implies, raise the blood level of glucose when severe hypoglycae- mia occurs (less than 4.4 mmol/L [40 mg/dL]). Some adverse conditions are associated with hypoglycaemia, including pancreatic disorders, kidney disease, certain cancers, disorders of the anterior pituitary and unbal- anced treatment of diabetes mellitus (which can occur if the person takes the wrong dose of insulin or oral hypo- glycaemic agents or if something interferes with food intake or changes stress or exercise levels). One agent is used to elevate glucose in these conditions: glucagon ( GlucaGen ). Pure glucose can also be given orally or intravenously to increase glucose levels. schedule for follow-up and disease monitoring; and the need for follow-up lab testing to enhance knowledge of drug therapy and to promote compliance. Evaluation ■ ■ Monitor the person’s response to the drug (stabilisation of blood glucose levels). ■ ■ Monitor for adverse effects (hypoglycaemia, GI distress). ■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for and specific measures to avoid them). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. KEY POINTS

TABLE 38.4

DRUGS IN FOCUS Glucose-elevating agent

Drug name

Dosage/route

Usual indications

Adults and children >20 kg: 0.5–1 mg SC, IM or IV Children <20 kg: 0.5 mg SC, IM or IV

To counteract severe hypoglycaemic reactions

glucagon (GlucaGen)