INSULIN (REGULAR)

(in'su-lyn)

Humulin R, Novolin R, Regular Insulin, Velosulin BR
Classifications: hormone; antidiabetic agent; insulin short-acting;
Therapeutic: antidiabetic; insulin short-acting
Pregnancy Category: B

Availability

100 units/mL

Action

Short-acting, clear, colorless solution of exogenous unmodified insulin extracted from beta cells in pork pancreas or synthesized by recombinant DNA technology (human). Enhances transmembrane passage of glucose across cell membranes in muscle and adipose tissue. Promotes conversion of glucose to glycogen in the liver.

Therapeutic Effect

It lowers blood glucose levels by increasing peripheral glucose uptake and by inhibiting the liver from changing glycogen to glucose.

Uses

Emergency treatment of diabetic ketoacidosis or coma, to initiate therapy in patient with insulin-dependent diabetes mellitus, and in combination with intermediate-acting or long-acting insulin to provide better control of blood glucose concentrations in the diabetic patient. Used IV to stimulate growth hormone secretion (glucose counter regulatory hormone) to evaluate pituitary growth hormone reserve in patient with known or suspected growth hormone deficiency. Other uses include promotion of intracellular shift of potassium in treatment of hyperkalemia (IV) and induction of hypoglycemic shock as therapy in psychiatry.

Contraindications

Hypersensitivity to insulin animal protein; children <1 y.

Cautious Use

Renal impairment, renal failure; hepatic impairment, fever, thyroid disease; older adults; pregnancy (category B), children and infants.

Route & Dosage

Diabetes Mellitus
Adult: SC 5–10 U 15–30 min a.c. and h.s. (dose adjustments based on blood glucose determinations)
Child: SC 2–4 U 15–30 min a.c. and h.s. (dose adjustments based on blood glucose determinations)

Ketoacidosis
Adult: IV 2.4–7.2 U loading dose, followed by 2.4–7.2 U/h continuous infusion
Child: IV 0.1 U/kg loading dose, followed by 0.1 U/h continuous infusion

Administration

Note: Insulins should not be mixed unless prescribed by physician. In general, regular insulin is drawn up into syringe first. Any change in the strength (e.g., U-40, U-100), brand (manufacturer), purity, type (regular, etc.), species (pork, human), or sequence of mixing two kinds of insulin is made by the physician only, since a simultaneous change in dosage may be necessary.

Subcutaneous

Use an insulin syringe.
Give regular insulin 30 min before a meal.
Avoid injection of cold insulin; it can lead to lipodystrophy, reduced rate of absorption, and local reactions.
Common injection sites: Upper arms, thighs, abdomen [avoid area over urinary bladder and 2 in. (5 cm) around navel], buttocks, and upper back (if fat is loose enough to pick up). Rotate sites.

Intravenous

PREPARE: Direct: Give undiluted. Continuous: Typically diluted in NS or 0.45% NaCl. 100 U added to 1000 mL yields 0.1 U/mL.

ADMINISTER: Direct: Give 50 U or a fraction thereof over 1 min. Continuous: Rate must be ordered by physician.

INCOMPATIBILITIES Solution/additive: Aminophylline, amobarbital, chlorothiazide, cytarabine, dobutamine, pentobarbital, phenobarbital, phenytoin, secobarbital, sodium bicarbonate, thiopental. Y-site: Dobutamine.

Regular insulin may be adsorbed into the container or tubing when added to an IV infusion solution. Amount lost is variable and depends on concentration of insulin, infusion system, contact duration, and flow rate.
Monitor patient response closely.

Insulin is stable at room temperature up to 1 mo. Avoid exposure to direct sunlight or to temperature extremes [safe range is wide: 5°–38° C (40°–100° F)]. Refrigerate but do not freeze stock supply. Insulin tolerates temperatures above 38° C with less harm than freezing.

Adverse Effects (≥1%)

Body as a Whole: Most adverse effects are related to hypoglycemia; anaphylaxis (rare), hyperinsulinemia (profuse sweating, hunger, headache, nausea, tremulousness, tremors, palpitation, tachycardia, weakness, fatigue, nystagmus, circumoral pallor); numb mouth, tongue, and other paresthesias; visual disturbances (diplopia, blurred vision, mydriasis), staring expression, confusion, personality changes, ataxia, incoherent speech, apprehension, irritability, inability to concentrate, personality changes, uncontrolled yawning, loss of consciousness, delirium, hypothermia, convulsions, Babinski reflex, coma. (Urine glucose tests will be negatives.) CNS: With overdose, psychic disturbances (i.e., aphasia, personality changes, maniacal behavior). Metabolic: Posthypoglycemia or rebound hyperglycemia (Somogyi effect), lipoatrophy and lipohypertrophy of injection sites; insulin resistance. Skin: Localized allergic reactions at injection site; generalized urticaria or bullae, lymphadenopathy.

Diagnostic Test Interference

Large doses of insulin may increase urinary excretion of VMA. Insulin can cause alterations in thyroid function tests and liver function test and may decrease serum potassium and serum calcium.

Interactions

Drug: Alcohol, anabolic steroids, mao inhibitors, guanethidine, salicylates may potentiate hypoglycemic effects; dextrothyroxine, corticosteroids, epinephrine may antagonize hypoglycemic effects; furosemide, thiazide diuretics increase serum glucose levels; propranolol and other beta blockers may mask symptoms of hypoglycemic reaction. Herbal: Garlic, ginseng may potentiate hypoglycemic effects.

Pharmacokinetics

Absorption: Rapidly absorbed from IM and SC injections. Onset: 0.5–1 h. Peak: 2–4 h. Duration: 5–7 h. Distribution: Throughout extracellular fluids. Metabolism: In liver with some metabolism in kidneys. Elimination: <2% excreted in urine. Half-Life: Biological, up to 13 h.

Nursing Implications

Assessment & Drug Effects

Note: Frequency of blood glucose monitoring is determined by the type of insulin regimen and health status of the patient.
Lab tests: Periodic postprandial blood glucose, and HbA_1C. Test urine for ketones in new, unstable, and type 1 diabetes; if patient has lost weight, exercises vigorously, or has an illness; whenever blood glucose is substantially elevated.
Notify physician promptly for presence of acetone with sugar in the urine; may indicate onset of ketoacidosis. Acetone without sugar in the urine usually signifies insufficient carbohydrate intake.
Monitor for hypoglycemia (see Appendix F) at time of peak action of insulin. Onset of hypoglycemia (blood sugar: 50–40 mg/dL) may be rapid and sudden.
Check BP, I&O ratio, and blood glucose and ketones every hour during treatment for ketoacidosis with IV insulin.
Give patients with severe hypoglycemia glucagon, epinephrine, or IV glucose 10–50%. As soon as patient is fully conscious, give oral carbohydrate (e.g., dilute corn syrup or orange juice with sugar, Gatorade, or Pedialyte) to prevent secondary hypoglycemia.

Patient & Family Education

Learn correct injection technique.
Inject insulin into the abdomen rather than a near muscle that will be heavily taxed, if engaged in active sports.
Notify physician of local reactions at injection site; may develop 1–3 wk after therapy starts and last several hours to days, usually disappear with continued use.
Do not change prescription lenses during early period of dosage regulation; vision stabilizes, usually 3–6 wk.
Note: Hypoglycemia can result from excess insulin, insufficient food intake, vomiting, diarrhea, unaccustomed exercise, infection, illness, nervous or emotional tension, or overindulgence in alcohol.
Respond promptly to beginning symptoms of hypoglycemia. Severe hypoglycemia is an emergency situation. Take 4 oz (120 mL) of any fruit juice or regular carbonated beverage [1.5–3 oz (45–90 mL) for child] followed by a meal of longer-acting carbohydrate or protein food. Failure to show signs of recovery within 30 min indicates need for emergency treatment.
Carry some form of fast-acting carbohydrate (e.g., lump sugar, Life-Savers, or other candy) at all times to treat hypoglycemia.
Check blood glucose regularly during menstrual period; loss of diabetes control (hyperglycemia or hypoglycemia) is common; adjust insulin dosage accordingly, as prescribed by physician.
Notify physician of S&S of diabetic ketoacidosis.
Continue taking insulin during an illness, go to bed, and drink noncaloric liquids liberally (every hour if possible). Consult physician for insulin regulation if unable to eat prescribed diet.
Avoid OTC medications unless approved by physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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