Pharmacology and Nutrition

After studying this chapter, the student will be able to:

1. Identify the official and common names of insulins currently in use

2. Describe the mechanism of action of oral hypoglycemic agents

 

AGENTS USED TO TREAT HYPERGLYCEMIA AND HYPOGLYCEMIA

Diabetes mellitus is a complex disorder of carbohydrate, fat, and protein metabolism caused by lack or inefficient use of insulin in the body. Insulin is secreted by the beta cells of the islets of Langerhans in the pancreas. Most cases are due to a genetically determined pancreatic insufficiency.

However, diabetes may also be the result of other pancreatic or endocrine diseases or an autoimmune response, or it can be precipitated by certain forms of drug therapy. If not effectively controlled, diabetes mellitus may increase the client’s susceptibility to cardiovascular disease and potentially cause kidney and nerve damage, as well as vision

loss due to diabetic retinopathy.

Type 1 diabetics of the type 2 diabetics, 80% have the obese, type 2 form of the disease. An additional 10% have the stable, nonobese, type 2 form. Another 10% have the unstable, or brittle, type 2 form, similar to the type 1 form. To understand the pathophysiology of diabetes mellitus, one must be aware of how the body nor

INSULIN THERAPY

Commercial insulin preparations are generally available in concentrations of 100 units per milliliter (U-100) and 500 units per milliliter (U-500).

The U-500 strength can only be purchased with a prescription and is usually employed only in clients who have a marked insulin resistance and who, therefore, require doses of more than 200 units of insulin daily. This strength is used for implantable pumps.

Insulin preparations differ with respect to their:

onset and duration of action

degree of purity

source (cow, pig or human insulin)

The onset and duration of action of insulin may be controlled by modification of regular insulin.

Regular insulin has the most rapid onset and briefest duration of action. By precipitating

insulin with zinc, various modified insulins can be produced. Another way of modifying insulin to achieve a longer onset and duration of action is to precipitate insulin with zinc and a large protein, protamine. This results in NPH (intermediateacting) and protamine zinc (PZI) insulin products.

Because of the presence of protamine, some clients may experience an immunological reaction to these products.

 

ORAL HYPOGLYCEMIC AGENTS

Oral hypoglycemic agents stimulate pancreatic beta cells to secrete insulin. They may also

increase the degree of binding between insulin and insulin receptors or increase the number of receptors. Some pancreatic function is required for these drugs to act. Their use is limited to the noninsulin-dependent, type 2 diabetic who does not respond to diet control alone and who is unwilling or unable to use insulin when it may be indicated.

Metformin HCl (Glucophage) is an oral hypoglycemic agent in a chemical group known as

biguanides. This drug is used in clients who have not responded to sulfonylureas or in combination with a sulfonylurea drug to take advantage of the different action of each. The client using metformin should be observed for the possible development of lactic acidosis during treatment. Over time, the use of sulfonylureas may overstimulate the pancreas which, in essence, tires out the pancreas.

 

Oral Hypoglycemic Agents

Note: These drugs must be used only in conjunction with a thorough client education program and follow-up supervision.

Instruction must be provided about diet, foot care, and glucose testing, plus recognizing and treating diabetic acidosis and hypoglycemia.

An increase in dose or use of insulin therapy may be required when clients are under unusual stress.

Clients must avoid alcohol, as it may produce an Antabuse-like reaction, with vomiting, flushing, and excessive

perspiration, if using sulfonylureas or increased likelihood of lactic acidosis if using metformin.

Drugs known to interact with oral hypoglycemic agents to enhance their hypoglycemic effect include salicylates,

phenylbutazone, sulfonamides, MAO inhibitors, phenytoin, and anticoagulants.

Drugs that may increase blood glucose levels include liquid products sweetened with sugar, as well as oral nasal decongestants, such as phenylpropanolamine.

 

Storage and Care of Insulin and Supplies

1. Before injection, insulin is brought to room temperature. This minimizes local

skin reactions.

2. Many clients are instructed in the monitoring of blood glucose levels by use of a

visually or machine-read reagent strip.

3. Some drugs may cause false-positive tests for urinary glucose

 

Insulin Reactions and Diabetic Ketoacidosis

1. If unsure whether the client is experiencing an insulin reaction or diabetic ketoacidosis,

it is better to treat for an insulin reaction.

2. Insulin reactions are treated by giving approximately 4 oz of a sugar-containing

beverage or other rapidly absorbed sugar, if the client is able to swallow. This is

usually followed by administration of a complex carbohydrate or regularly

scheduled meal.

3. If unable to swallow, sugar-containing syrups or pastes may be applied to the

person’s buccal mucosa.

4. Family members should be taught how to reconstitute and administer glucagon.

5. Insulin is not administered to clients who are required to fast.

6. Beta-adrenergic blocking agents may mask the signs and symptoms of hypoglycemia.

Clients are taught to respond to subtle indicators such as weakness or dizziness