How to give insulin, heparin and warfarin safely
NCLEX-RN topic: Medication administration
- High-alert drugs cause severe harm when given in error.
- Check a current blood glucose before every insulin dose.
- IV heparin: follow the aPTT; protamine sulfate reverses it.
- Warfarin: follow the INR, usually 2.0 to 3.0; vitamin K reverses it.
- A platelet drop of 30% or more on heparin suggests HIT.
Key facts
- ISMP lists all insulin (subcutaneous and IV) and anticoagulants such as warfarin and heparin as high-alert medications.
- Before subcutaneous insulin, check the most current blood glucose, assess for hypoglycemia, and tell the client the insulin name, dose and action.
- Hypoglycemia is a blood glucose below 70 mg/dL; a client who can swallow gets 15 g of fast-acting carbohydrate, such as 4 oz of juice.
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- IV heparin is adjusted by the aPTT, usually to 1.5 to 2 times normal (normal PTT is about 25 to 35 seconds); subcutaneous prophylactic heparin needs no aPTT.
- Protamine sulfate reverses heparin; vitamin K reverses warfarin.
- A platelet drop of 30% or more from baseline on heparin suggests heparin-induced thrombocytopenia (HIT); heparin is stopped.
- INR is about 0.8 to 1.1 without warfarin; on warfarin the target is usually 2.0 to 3.0, and higher values raise bleeding risk.
Quick check1 question · 2 more at the end
A client with type 2 diabetes is scheduled to receive insulin lispro 6 units subcutaneously with breakfast. At 0730 the client is sweaty and shaky but alert and able to swallow. Point-of-care blood glucose is 62 mg/dL (fasting 70–99 mg/dL). Which action should the nurse take first?
Correct answer: C.
A glucose below 70 mg/dL with shakiness and sweating is hypoglycemia, and a client who can swallow is treated right away with 15 g of fast-acting carbohydrate per the agency protocol. Treating the immediate physiological threat comes before notifying the provider, which is still done to discuss the cause and insulin changes. Giving the scheduled rapid-acting insulin now would push the glucose even lower.
A Giving rapid-acting insulin to a client whose glucose is already 62 mg/dL would drive it lower and could cause severe hypoglycemia.
B Waiting 15 minutes delays treatment of symptomatic hypoglycemia; the recheck comes after the carbohydrate is given.
C Correct: an alert client who can swallow receives 15 g of rapidly absorbed carbohydrate immediately per the hypoglycemia protocol.
D The provider should be notified, but treating the low glucose comes first because the client is symptomatic now.
Full lesson
Each part starts with its main idea. Open a part when you want the details.
The short answer: High-alert medications cause severe harm when given in error. Before insulin, check the current blood glucose and hypoglycemia symptoms. IV heparin is guided by the aPTT and reversed with protamine sulfate. Warfarin is guided by the INR, usually kept at 2.0 to 3.0, and reversed with vitamin K. Watch all three for bleeding or low glucose.
1 What makes a medication "high-alert"?A high-alert medication is one whose errors cause much more harm than usual. 1 min
A high-alert medication is one whose errors cause much more harm than usual. The Institute for Safe Medication Practices (ISMP) notes that these errors may not happen more often, but their consequences are far worse.
ISMP's acute care list includes all insulin, subcutaneous and IV, and the anticoagulants, including warfarin, unfractionated heparin and low molecular weight heparin. Safeguards include standard order sets and storage, auxiliary labels, automated alerts and independent double checks where they help.
| Drug | What you check | Reversal | Main danger |
|---|---|---|---|
| Insulin | Current blood glucose, meal timing, potassium | Fast carbohydrate, IV dextrose or glucagon | Hypoglycemia, hypokalemia |
| Heparin (IV) | aPTT, platelets, bleeding | Protamine sulfate | Bleeding, HIT |
| Warfarin | PT/INR, bleeding | Vitamin K | Bleeding |
2 How do you give insulin safely?Every insulin dose starts with a fresh blood glucose and a look at the client. 1 min
Every insulin dose starts with a fresh blood glucose and a look at the client. Before subcutaneous insulin, the nurse confirms the indication, checks the most current glucose, assesses for hypoglycemia, and tells the client the product name, dose and intended action.
- Rapid-acting (insulin lispro, insulin aspart): give within 15 minutes before or right after a meal; blood levels peak 30 to 90 minutes after the dose.
- Short-acting (regular insulin): about 30 minutes before meals; peaks about 3 hours. Regular insulin can be given IV with close glucose and potassium monitoring.
- Intermediate (NPH): cloudy; roll to mix. When mixing, draw the clear insulin into the syringe before the NPH.
- Long-acting (insulin glargine): no pronounced peak.
Use one insulin pen for one client only, even with a new needle. Measure U-500 only with a U-500 syringe. Never base a dose only on a glucose value someone told you verbally. Insulin moves potassium into cells, so it can cause hypokalemia.
Hypoglycemia is a glucose below 70 mg/dL. If the client can swallow, give 15 g of fast-acting carbohydrate (such as 4 oz of juice) per protocol. If the client is NPO or can't swallow, the protocol uses IV dextrose 50% or glucagon.
3 How is heparin monitored and reversed?IV heparin is adjusted by the aPTT, and its antidote is protamine sulfate. 1 min
IV heparin is adjusted by the aPTT, and its antidote is protamine sulfate. Most hospitals use weight-based protocols that titrate the dose to the aPTT; the label calls the dose adequate when the aPTT is 1.5 to 2 times normal. A normal PTT is about 25 to 35 seconds. Subcutaneous heparin given to prevent DVT doesn't need aPTT monitoring.
Heparin comes in many strengths and wrong-strength errors have been fatal, so confirm the strength every time. Bleeding is the chief sign of overdose: bruising, petechiae, nosebleeds, blood in urine, or tarry stools. A falling blood pressure with a rising heart rate can mean internal bleeding.
Watch platelets too. A drop of 30% or more from baseline suggests heparin-induced thrombocytopenia (HIT), and heparin is stopped. Heparin keeps new clots from forming but does not break down an existing clot.
4 How is warfarin monitored and reversed?Warfarin blocks vitamin K-dependent clotting factors, so the INR guides it and vitamin K reverses it. 1 min
Warfarin blocks vitamin K-dependent clotting factors, so the INR guides it and vitamin K reverses it. Without warfarin, the INR is about 0.8 to 1.1; on warfarin the usual target is 2.0 to 3.0, though some indications go up to 3.5. Too high means bleeding risk; too low means clotting risk.
In the hospital, IV heparin often overlaps with warfarin until the INR is therapeutic. Teaching includes a consistent intake of vitamin K foods, avoiding alcohol, cranberries and grapefruit, using an electric razor, and reporting bleeding such as dark stools or bleeding gums.
5 What the nurse doesThe same three-step habit of assess, act and teach keeps all three drugs safe. 1 min
The same three-step habit of assess, act and teach keeps all three drugs safe.
- Assess: glucose before insulin; aPTT, platelets and bleeding before heparin; INR and bleeding before warfarin.
- Act: follow the protocol for an out-of-range aPTT, report new bleeding or an INR above target to the provider right away, and treat low glucose by protocol.
- Teach: bleeding precautions (avoid aspirin and NSAIDs, use a soft toothbrush and an electric razor) and the signs of hypoglycemia.
Common mistakes
The traps students fall into most. Read these before you practice.
Watch out: Heparin is monitored with the aPTT, not the INR; warfarin is monitored with the INR.
Watch out: Vitamin K reverses warfarin, not heparin; heparin's reversal agent is protamine sulfate.
Watch out: Warfarin teaching is a consistent vitamin K intake, not avoiding green vegetables completely.
Watch out: Draw clear rapid- or short-acting insulin into the syringe before cloudy NPH, not the other way around.
Watch out: Heparin prevents new clots from forming; it does not break down a clot that already exists.
How to remember it
Two memory hooks link each anticoagulant to its lab and antidote. Heparin has two P's, aPTT and Protamine. Warfarin is a WINK: Warfarin, INR, vitamin K.
Self-check:
- Name the lab and the antidote for IV heparin and for warfarin.
- List three checks before giving subcutaneous insulin.
- Say what a platelet count falling from 240,000 to 120,000 on heparin suggests.