insulin (cont.)

A mixture of 50% NPH human insulin and 50% regular human insulin (Humulin 50/50) is available in vials.

Lente human insulin (Novolin L, Humulin L) is available in vials.

Ultralente human insulin (Humulin U) is available in vials.

Insulin lispro (Humalog) is available in vials and cartridges.

Insulin aspart (Novolog) is available in vials and cartridges.

Insulin glargine (Lantus) is available in vials and cartridges.

STORAGE: Unopened insulin should be stored in a refrigerator between 2 and 8°C (36 and 46°F); it should not be placed in a freezer. Insulin vials that are being used can be kept at room temperature for up to a month. All vials should be protected from light and excessive heat. Unused insulin should be thrown away after the expiration date. The vials should never be shaken.

PRESCRIBED FOR: Insulin is prescribed for the treatment of type 1 and type 2 diabetes mellitus.

DOSING: The abdomen is the preferred site for insulin injection, but the sites of injection must be rotated in order to prevent erosion of the fat beneath the skin, a condition called lipodystrophy.

DRUG INTERACTIONS: Several drugs augment the action of insulin and may lower blood glucose to a dangerous level (hypoglycemia). To prevent hypoglycemia when these drugs are used, the dose of insulin may need to be reduced. Such drugs include alcohol, MAO inhibitors like phenelzine (Nardil), beta-blockers like propranolol (Inderal), salicylates like aspirin (Bayer) or salsalate (Disalcid), and anabolic steroids like methyltestosterone (Android).

There are other drugs that augment the blood glucose-lowering effect of insulin, but they are less likely to interact with insulin or have less of an effect. Such drugs include tetracycline antibiotics like doxycycline (Vibramycin), guanethidine (Ismelin), oral hypoglycemic drugs like glyburide (Diabeta), sulfa antibiotics like sulfadiazine, and ACE inhibitors like captopril (Capoten).

There also are drugs that decrease the effect of insulin. Interactions are less likely and/or less serious. These drugs include diltiazem (Cardizem), niacin, corticosteroids like prednisone, estrogens, oral contraceptives, thyroid hormones like levothyroxine (Synthroid), isoniazid, epinephrine, thiazide diuretics like hydrochlorothiazide, and furosemide (Lasix).

PREGNANCY: Insulin is the drug of choice for controlling diabetes mellitus during pregnancy, that is, it is preferred over oral drugs to reduce blood sugar. Regular human insulin is preferred over insulin aspart or insulin glargine during pregnancy since the latter two insulins have not been studied in pregnant women. NPH, lente, and ultralente insulins also may be used in pregnancy.

NURSING MOTHERS: It is not known if insulin aspart, insulin glargine or insulin lispro are secreted in breast milk. Regular human insulin is secreted in to breast milk. Therefore, when insulin is used during breastfeeding, blood glucose levels should be monitored in both the mother and child.

SIDE EFFECTS: Hypoglycemia is the most common side effect that may occur during insulin therapy. Symptoms of hypoglycemia include confusion, nausea, hunger, tiredness, perspiration, headache, heart palpitations, numbness around the mouth, tingling in the fingers, tremors, muscle weakness, blurred vision, cold temperature, excessive yawning, irritability, and loss of consciousness.

Patients may experience blurred vision if they have had elevated blood sugar levels for a prolonged period of time and then have the elevated levels rapidly brought to normal. This is due to a shift of fluid within the lens of the eye. Over time, vision returns to normal. Other possible side effects that may occur include skin reactions (redness, swelling, itching or rash at the site of injection), worsening of diabetic retinopathy, changes in the distribution of body fat (lipodystrophy), allergic reactions, sodium retention, and general body swelling.

Reference: FDA Prescribing Information

Last Editorial Review: 3/26/1998 2:30:00 PM

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