Insulin Isophane (NPH - Neutral Protamine Hagedorn) is an intermediate-acting insulin suspension used for the management of diabetes mellitus. It is a cloudy, white suspension of human insulin complexed with protamine and zinc, providing a longer duration of action than regular insulin. In India, the 40 IU/mL concentration (U-40) is a legacy strength, though U-100 (100 IU/mL) is now the global standard. U-40 requires specific U-40 syringes for accurate dosing.
Adult: Highly individualized. Typical starting dose in insulin-naïve Type 2 DM: 0.1-0.2 IU/kg/day, usually administered once daily (at bedtime) or twice daily. Dose is titrated based on fasting blood glucose levels.
Note: FOR SUBCUTANEOUS USE ONLY. Administer by subcutaneous injection in the abdominal wall, thigh, buttock, or upper arm. Rotate injection sites within the same region to prevent lipodystrophy. Gently roll the vial to resuspend the cloudy suspension; DO NOT SHAKE VIGOROUSLY. Use a U-40 insulin syringe. Inject at a 90-degree angle (or 45 degrees if thin). Typically administered 30-60 minutes before a meal (if used twice daily) or at bedtime (if used once daily).
Insulin Isophane is a suspension of insulin complexed with protamine and zinc, which delays absorption from the subcutaneous injection site. Once absorbed, it binds to the insulin receptor, a transmembrane tyrosine kinase receptor, initiating a cascade of intracellular signaling events.
Pregnancy: Pregnancy Category B (US FDA). Insulin is the drug of choice for glycemic control in pregnancy (both pre-existing and gestational diabetes). Requirements may decrease in first trimester and increase significantly in second/third trimesters. Close monitoring of blood glucose is mandatory.
Driving: Caution required. Patients must check blood glucose before driving and regularly during long journeys. They should be aware of hypoglycemia symptoms and keep a fast-acting carbohydrate source (glucose tablets) readily available.
| Beta-blockers (e.g., Propranolol) | Mask tachycardia warning signs of hypoglycemia; may potentiate or impair glucose recovery. | Major |
| Corticosteroids (e.g., Prednisone) | Increase insulin requirements due to hyperglycemic effect. | Major |
| Thiazide Diuretics (e.g., Hydrochlorothiazide) | May increase blood glucose levels, increasing insulin requirements. | Moderate |
| ACE Inhibitors (e.g., Ramipril) | May enhance hypoglycemic effect. | Moderate |
| Alcohol | Potentiates hypoglycemic effect; can cause delayed hypoglycemia, especially in fasting state. | Major |
| MAO Inhibitors, Anabolic Steroids | Increase hypoglycemic effect. | Moderate |
| Oral Hypoglycemics (e.g., Sulfonylureas) | Additive hypoglycemic effect, increasing hypoglycemia risk. | Major |
Same composition (Insulin Isophane (40IU)), different brands: