HUMULIN R PEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HUMULIN R PEN (HUMULIN R PEN).
Insulin is a hormone produced by the pancreas that regulates glucose metabolism. Exogenous insulin replaces endogenous insulin, binding to insulin receptors on cell surfaces, activating tyrosine kinase activity, and promoting glucose uptake, glycogen synthesis, and lipogenesis while inhibiting gluconeogenesis and lipolysis.
| Metabolism | The metabolic pathways of insulin involve degradation by insulin protease or insulin-degrading enzyme, and insulin is primarily cleared by the liver, kidneys, and muscle tissue. |
| Excretion | Primarily renal (hepatic metabolism to inactive metabolites accounts for <20%); ~30-80% of dose excreted unchanged in urine via glomerular filtration. |
| Half-life | Intravenous: plasma half-life is ~5-10 minutes (distribution) and elimination half-life ~1.5-2 hours (reflecting clearance from peripheral compartments). Subcutaneous: prolonged due to absorption rate-limited kinetics; terminal half-life ~5-10 hours. |
| Protein binding | ~10-20% bound (primarily to albumin, but binding is weak and non-saturable at therapeutic concentrations). |
| Volume of Distribution | 0.1-0.2 L/kg (restricted to extracellular fluid; does not cross placenta or blood-brain barrier significantly). |
| Bioavailability | Subcutaneous: 55-80% (due to local degradation and incomplete absorption; absorption site, blood flow, and dose influence bioavailability). Intramuscular: 80-100% (more consistent). |
| Onset of Action | Subcutaneous: 0.25-0.5 hours (regular insulin); Intravenous: <0.1 hours (immediate). |
| Duration of Action | Subcutaneous: 5-8 hours (short-acting). Duration dose-dependent: higher doses (e.g., 0.5 U/kg) may extend to ~8 hours; lower doses (0.1 U/kg) ~5-6 hours. Intravenous: ~1-2 hours (rapid clearance from blood). |
Subcutaneous injection, usual starting dose 0.2 to 0.4 units/kg/day divided into two or more injections; total daily insulin requirements may range from 0.5 to 1.0 units/kg/day.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment guidelines; insulin requirements may decrease due to reduced insulin clearance; monitor blood glucose closely and adjust dose accordingly. |
| Liver impairment | No Child-Pugh based dose adjustment; hepatic impairment may alter glucose metabolism; monitor glucose levels and adjust insulin dose as needed. |
| Pediatric use | Individualized; typical starting dose 0.2 to 0.4 units/kg/day subcutaneously divided into multiple injections; dose titrated based on blood glucose monitoring. |
| Geriatric use | Initiate at lower doses (e.g., 0.2 units/kg/day) due to increased risk of hypoglycemia; titrate based on glucose monitoring; avoid long-acting insulins; prefer regular insulin for prandial coverage. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HUMULIN R PEN (HUMULIN R PEN).
| Breastfeeding | Insulin is secreted into breast milk in negligible amounts and is not orally bioavailable. M/P ratio not determined; considered compatible with breastfeeding. |
| Teratogenic Risk | Insulin does not cross the placenta in significant amounts and is not associated with an increased risk of major congenital anomalies. Poor glycemic control increases fetal risk for malformations, macrosomia, and neonatal hypoglycemia. |
| Fetal Monitoring |
■ FDA Black Box Warning
Changes in insulin strength, manufacturer, type, or method of administration may affect glycemic control and predispose to hypoglycemia or hyperglycemia. Any change should be made cautiously and under close medical supervision.
| Serious Effects |
["Hypersensitivity to insulin or any excipients (absolute)","During episodes of hypoglycemia (absolute)"]
| Precautions | ["Hypoglycemia is the most common adverse effect; careful monitoring and dosage adjustment are required.","Medication errors can occur due to confusion between different insulin products; verify product before administration.","Fluid retention and heart failure may occur with concomitant use of thiazolidinediones (TZDs).","Hypersensitivity reactions, including anaphylaxis, have been reported.","Changes in renal or hepatic function may necessitate dosage adjustments."] |
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| Monitor blood glucose, HbA1c, and fetal growth via ultrasound. Assess for maternal hypoglycemia and diabetic ketoacidosis. Fetal surveillance including non-stress test and biophysical profile in third trimester. |
| Fertility Effects | No direct effects on fertility. Improved glycemic control may restore normal ovulatory function in women with diabetes-related infertility. |