Humulin I (Isophane)

Humulin I (Isophane) is a recombinant human insulin (isophane) supplied as an injectable suspension for subcutaneous administration. The product contains insulin human (rDNA) in a premixed formulation, with the exact strength not specified on the label. It is marketed in the European Union as a prescription‑only antidiabetic agent used to manage blood glucose levels in patients with diabetes mellitus and is intended for use under medical supervision.

Humulin I (Isophane) is indicated for the treatment of diabetes mellitus when basal insulin coverage is required.

- Type 1 diabetes mellitus in adults and children. - Type 2 diabetes mellitus as part of a basal insulin regimen. - Adjunct therapy when oral antidiabetic agents are insufficient. - Use in patients requiring a long‑acting insulin to maintain fasting glucose control. - May be combined with rapid‑acting insulin for flexible dosing.

Adverse reactions reported with Humulin I (Isophane) are generally related to its insulin activity and formulation components.

Common: - Hypoglycemia, especially if meals are missed or dosing is excessive. - Injection site reactions such as redness, swelling, or itching. - Lipodystrophy at the injection site. - Weight gain associated with improved glycemic control. - Transient blurred vision due to rapid glucose changes. - Nausea or abdominal discomfort after injection. - Mild headache or dizziness during dose adjustments.

Serious: - Severe hypoglycemia with neuroglycopenic symptoms. - Allergic reactions including urticaria, angioedema, or anaphylaxis. - Lipohypertrophy leading to erratic insulin absorption. - Edema or heart failure exacerbation in susceptible patients. - Hypersensitivity leading to serum sickness‑like reaction.

When prescribing Humulin I (Isophane), clinicians should consider several precautions to minimize risks and ensure safe use.

- Assess renal and hepatic function before initiating therapy, as impairment may alter insulin clearance. - Monitor blood glucose closely during periods of illness, stress, or changes in physical activity. - Adjust dose in pregnant or lactating women, recognizing altered insulin requirements. - Use caution in patients with a history of severe hypoglycemia or unawareness of symptoms. - Inspect injection sites regularly for lipodystrophy or infection. - Evaluate cardiovascular status in patients with heart failure, as fluid retention may worsen symptoms.

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

Avoid: - Concurrent use of other rapid‑acting insulins without dose adjustment, which can cause severe hypoglycemia. - Combination with sulfonylureas or meglitinides without careful monitoring, increasing hypoglycemia risk. - Concurrent use of meglitinides with overlapping action profiles may cause additive hypoglycemia.

Use with caution: - Beta‑blockers, which may mask hypoglycemia symptoms. - Corticosteroids, which can raise blood glucose and require insulin dose increase. - Diuretics, especially thiazides, that may affect potassium levels and glucose control. - ACE inhibitors or ARBs, which may potentiate insulin’s antihyperglycemic effect. - Thyroid hormones, which can accelerate insulin metabolism and alter glycemic control.