Humulin I (Isophane) (Insulin Human (Rdna))

Humulin I (Isophane) is indicated for the management of hyperglycemia in adults and children with diabetes.

• Basal insulin therapy for type 1 diabetes mellitus.
• Supplemental basal coverage in type 2 diabetes mellitus when diet, exercise, and oral agents are insufficient.
• Combination with rapid‑acting insulin analogues to provide a basal‑bolus regimen.
• Use in insulin‑pump therapy only when specifically prescribed (off‑label in some regions).

• Humulin I (Isophane) is a recombinant human insulin that binds to insulin receptors on muscle, adipose and hepatic cells. Receptor activation triggers autophosphorylation and downstream signaling through the PI3‑K/Akt pathway, promoting translocation of GLUT‑4 transporters to the cell surface and increasing glucose uptake. In the liver, it suppresses gluconeogenesis and glycogenolysis, thereby lowering circulating glucose levels over an intermediate duration.

Adverse reactions to Humulin I (Isophane) may vary in frequency and severity.

Common

• Pain, redness, swelling, or bruising at the injection site, usually mild and transient.
• Mild to moderate hypoglycemia, often occurring if a meal is missed, delayed, or carbohydrate intake is reduced.
• Localized lipodystrophy, presenting as lipoatrophy or lipohypertrophy at repeated injection sites.
• Gradual weight gain, typically modest and related to improved glycemic control.
• Nausea, occasional abdominal discomfort, or a feeling of fullness after injection.
• Headache, light‑headedness, or dizziness that resolves without intervention.

Serious

• Severe hypoglycemia with neuroglycopenic signs such as confusion, seizures, or loss of consciousness.
• Allergic reactions ranging from urticaria and angioedema to full‑body anaphylaxis requiring emergency treatment.
• Fluid retention, peripheral edema, or worsening of pre‑existing heart failure, especially in patients with cardiac disease.
• Hypersensitivity responses that may manifest as serum‑sickness–like syndrome, including fever, rash, and arthralgia.

When prescribing or using Humulin I (Isophane), clinicians and patients should consider several safety precautions to minimize risk.

• Assess renal and hepatic function before initiating therapy and monitor periodically.
• Adjust dose in patients with fluctuating dietary intake, physical activity, or concurrent illness.
• Use caution in pregnant or breastfeeding women; benefits must outweigh potential risks.
• Educate patients on recognizing and treating hypoglycemia promptly.
• Avoid use in individuals with known hypersensitivity to human insulin or any excipients.
• Monitor for signs of fluid retention or worsening heart failure, especially in cardiac patients.
• Store the product according to label instructions and discard after the recommended in‑use period.

Humulin I (Isophane) may interact with other medications that affect glucose metabolism or insulin action.

Avoid

• Concurrent use of other rapid‑acting insulin preparations without dose adjustment, which can cause severe hypoglycemia.
• Beta‑blockers that mask hypoglycemia symptoms and may prolong insulin’s glucose‑lowering effect.

Use with caution

• Oral antidiabetic agents (e.g., sulfonylureas, meglitinides) that increase the risk of additive hypoglycemia.
• Corticosteroids, thiazide diuretics, or sympathomimetics that raise blood glucose and may require higher insulin doses.
• Alcohol consumption, especially in excess, which can cause delayed hypoglycemia.
• Anticoagulants such as heparin, which may alter insulin absorption at the injection site.