Humulin I (Isophane) (Insulin Human)

Humulin I (Isophane) is indicated for the long‑term control of blood glucose in patients with diabetes mellitus.

• Type 1 diabetes mellitus as part of basal insulin regimen.
• Type 2 diabetes mellitus when basal insulin is required.
• Combination therapy with rapid‑acting insulin analogues to achieve basal‑bolus coverage.
• Use in adults and pediatric patients when a steady, intermediate‑acting insulin profile is needed.
• May be employed during pregnancy under medical supervision if benefits outweigh risks.

• Humulin I (Isophane) contains 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, increasing glucose uptake, and inhibiting gluconeogenesis in the liver. The isophane protamine complex slows absorption, providing an intermediate duration of action and helps maintain basal insulin levels.

Adverse reactions to Humulin I (Isophane) are reported in clinical practice and may vary in frequency and severity.

Common

• Hypoglycemia (low blood glucose)
• Injection site reactions such as redness, swelling or itching
• Lipodystrophy (localized fat loss or accumulation)
• Weight gain
• Mild nausea or abdominal discomfort
• Transient headache
• Transient dizziness
• Mild skin discoloration at injection site

Serious

• Severe allergic reaction (anaphylaxis, angioedema)
• Hypokalemia (low potassium)
• Persistent hyperglycemia due to insulin resistance
• Edema or heart failure exacerbation
• Seizures related to severe hypoglycemia
• Acute pancreatitis (rare)
• Severe hypoglycemia leading to loss of consciousness

When using Humulin I (Isophane), several precautionary measures should be observed to minimize risks and ensure optimal therapeutic outcomes.

• Verify blood glucose before each dose to avoid hypoglycemia.
• Rotate injection sites to reduce lipodystrophy and tissue irritation.
• Adjust dose during periods of illness, stress, or changes in physical activity.
• Store the product in a refrigerator and avoid freezing; allow it to reach room temperature before injection.
• Use caution in patients with renal or hepatic impairment, as insulin clearance may be reduced.
• Monitor for signs of allergic reactions, especially after the first few administrations.
• Discuss pregnancy or breastfeeding plans with a healthcare professional before initiating therapy.

Humulin I (Isophane) may interact with other medicines, affecting glucose control or increasing the risk of adverse events.

Avoid

• Concurrent use of other rapid‑acting insulins without proper dose adjustment (risk of severe hypoglycemia)
• High‑dose beta‑blockers that mask hypoglycemia symptoms
• Use of MAO inhibitors in combination may lead to unpredictable insulin effects.

Use with caution

• Oral antidiabetic agents (e.g., sulfonylureas, meglitinides) – may potentiate hypoglycemia
• Corticosteroids – may increase insulin requirements
• Diuretics (especially thiazides) – can affect potassium levels and glucose
• ACE inhibitors or ARBs – may enhance insulin sensitivity, requiring dose review
• Alcohol consumption – can cause unpredictable glucose fluctuations
• Thyroid hormones – may increase metabolic rate and alter insulin requirements.