Critical safety information for insulin, heparin, warfarin, digoxin, lithium, potassium, and chemotherapy agents.
High-Alert Medications Overview
High-alert medications carry a heightened risk of causing significant patient harm when used in error. These require independent double-checks, special storage, and clear labeling.
Insulin
| Type | Onset | Peak | Duration |
|---|
| Rapid-acting (lispro, aspart, glulisine) | 15 min | 1 – 2 hrs | 3 – 4 hrs |
| Short-acting (Regular) | 30 – 60 min | 2 – 4 hrs | 6 – 8 hrs |
| Intermediate (NPH) | 2 – 4 hrs | 4 – 12 hrs | 12 – 18 hrs |
| Long-acting (glargine, detemir) | 1 – 2 hrs | No peak | 24 hrs |
Insulin Safety Rules
- Only Regular insulin can be given IV
- Always verify with a second nurse before administration
- Never shake insulin — gently roll NPH (cloudy)
- When mixing: draw clear (Regular) before cloudy (NPH)
- Do NOT mix glargine (Lantus) with any other insulin
- Rotate injection sites; monitor for lipodystrophy
- Monitor blood glucose before meals and at bedtime
- Hypoglycemia signs: tremors, diaphoresis, tachycardia, confusion
Heparin
| Parameter | Details |
|---|
| Route | IV (continuous drip) or SubQ (prophylaxis) |
| Monitoring | aPTT every 6 hours; therapeutic: 1.5 – 2.5 × control (46 – 70 sec) |
| Antidote | Protamine sulfate (1 mg per 100 units heparin) |
| Side Effects | Bleeding, HIT (heparin-induced thrombocytopenia) |
Heparin Safety
- Monitor platelet count — discontinue if platelets drop > 50% (HIT)
- Avoid IM injections; apply pressure to venipuncture sites
- Assess for signs of bleeding: petechiae, hematuria, tarry stools, gum bleeding
- Keep protamine sulfate at bedside
Warfarin (Coumadin)
| Parameter | Details |
|---|
| Route | PO only |
| Onset | 36 – 72 hours (overlap with heparin for 4 – 5 days) |
| Monitoring | PT/INR; therapeutic INR: 2.0 – 3.0 (mechanical valve: 2.5 – 3.5) |
| Antidote | Vitamin K (phytonadione) |
Warfarin Teaching Points
- Maintain consistent vitamin K intake (do not eliminate, just keep steady)
- Avoid: NSAIDs, aspirin, cranberry juice, alcohol
- Use soft toothbrush, electric razor
- Report unusual bruising, bleeding gums, dark stools
- Multiple drug interactions — check every new medication
Digoxin (Lanoxin)
| Parameter | Details |
|---|
| Therapeutic Level | 0.5 – 2.0 ng/mL |
| Action | Positive inotrope, negative chronotrope/dromotrope |
| Antidote | Digoxin immune Fab (Digibind) |
Digoxin Safety
- Hold if apical pulse < 60 bpm (adults) or < 70 bpm (children)
- Take apical pulse for a full 60 seconds before giving
- Toxicity signs: anorexia, nausea, vomiting, visual changes (yellow-green halos), bradycardia
- Hypokalemia increases digoxin toxicity — monitor K+ closely
- Do not give with antacids (decreases absorption)
Lithium
| Parameter | Details |
|---|
| Therapeutic Level | 0.6 – 1.2 mEq/L |
| Toxic Level | > 1.5 mEq/L |
| Use | Bipolar disorder (mood stabilizer) |
Lithium Safety
- Draw levels 8 – 12 hours after last dose
- Maintain adequate sodium and fluid intake (dehydration increases toxicity)
- Toxicity signs: coarse tremors, vomiting, diarrhea, confusion, seizures
- Monitor renal and thyroid function (can cause hypothyroidism and nephrogenic DI)
- Avoid NSAIDs and diuretics (increase lithium levels)
- No antidote — treatment is hydration and dialysis
IV Potassium
- NEVER give IV push — can cause fatal cardiac arrest
- Max rate: 10 mEq/hr peripheral; 20 mEq/hr central line
- Always dilute; use an infusion pump
- Assess IV site frequently (KCl is a vesicant — causes tissue necrosis)
- Monitor cardiac rhythm during infusion
- Verify urine output > 30 mL/hr before and during infusion
Chemotherapy Safety
- Verify with two nurses using the original prescriber order
- Administer only by chemotherapy-certified nurses
- Wear PPE during preparation and administration
- Monitor for extravasation — stop infusion immediately if suspected
- Monitor CBC frequently — nadir typically 7 – 14 days post-treatment
- Implement neutropenic precautions when ANC < 1,000
- Dispose of waste in designated chemotherapy waste containers