Vitamin K

# Vitamin K ## Overview - **Classification**: Fat-soluble vitamin, Anticoagulant antagonist - **Mechanism**: Essential cofactor for gamma-carboxylation of coagulation factors II, VII, IX, X, and anticoagulant proteins C and S, promoting their activation. ## Primary Indications 1. **Reversal of Anticoagulation**: Specifically for warfarin-induced coagulopathy or bleeding. 2. **Vitamin K Deficiency Bleeding (VKDB)**: Prophylaxis and treatment in neonates. 3. **Hypoprothrombinemia**: Due to vitamin K deficiency states (e.g., malabsorption, obstructive jaundice). ## Adult Dosing ### Standard Dosing **Warfarin Reversal (Elevated INR without significant bleeding)** - **Dose**: **2.5-5 mg** - **Frequency**: Once, or repeat as needed based on INR response - **Route**: Oral (PO) is preferred for non-emergent situations - **Special considerations**: Often given when INR is >4.5-10.0 without bleeding. **Warfarin Reversal (Serious or Life-Threatening Bleeding / INR >10.0)** - **Dose**: **5-10 mg** - **Frequency**: Single dose, may repeat after 6-8 hours if INR still high - **Route**: Intravenous (IV) via slow infusion (over at least 30 minutes) - **Special considerations**: Administer with fresh frozen plasma (FFP) or prothrombin complex concentrate (PCC) for immediate effect. **Vitamin K Deficiency (Non-Warfarin related)** - **Dose**: **10 mg** - **Frequency**: Daily - **Route**: Oral (PO), Subcutaneous (SC), or Intramuscular (IM) - **Duration**: As needed based on underlying cause and response. ### Dose Adjustments - **Renal Impairment**: No specific renal dose adjustments are generally required. - **Hepatic Impairment**: No specific hepatic dose adjustments are generally required. - **Elderly Patients**: No specific dose adjustments needed; standard adult doses apply. Monitor closely for response. ## Pediatric Dosing ### Neonates (0-28 days) **VKDB Prophylaxis (Term infants, >2.5 kg)** - **Dose**: **1 mg** - **Frequency**: Single dose - **Route**: Intramuscular (IM) - **Special Notes**: Administer shortly after birth to prevent VKDB. **VKDB Prophylaxis (Preterm infants, <2.5 kg)** - **Dose**: **0.5 mg** - **Frequency**: Single dose - **Route**: Intramuscular (IM) - **Special Notes**: Administer shortly after birth. **VKDB Treatment** - **Dose**: **1 mg** - **Frequency**: Single dose, may repeat as clinically indicated - **Route**: Intravenous (IV) slow infusion (over 20-30 minutes) - **Maximum**: Not typically exceeded for single dose; total daily maximum up to **5 mg** if severe. - **Special Notes**: May be given with FFP if active bleeding. ### Infants (1-12 months) **Vitamin K Deficiency / Warfarin Reversal** - **Dose**: **1-2 mg** (for non-emergent reversal) - **Dose (serious bleeding/high INR)**: **2-5 mg IV** - **Frequency**: Once, or repeat based on INR - **Route**: PO, SC, IM, or IV (slow infusion) - **Maximum**: Up to **5 mg** daily for deficiency; up to **10 mg** for emergent reversal. ### Children (1-12 years) **Vitamin K Deficiency / Warfarin Reversal (Non-emergent)** - **Dose**: **2.5-5 mg** - **Frequency**: Once - **Route**: PO - **Maximum**: **10 mg** **Vitamin K Deficiency / Warfarin Reversal (Serious bleeding/high INR)** - **Dose**: **5-10 mg** - **Frequency**: Once, may repeat in 6-8 hours if needed - **Route**: Intravenous (IV) slow infusion (over 30 minutes) - **Maximum**: **10 mg** (adult dose equivalent) ### Adolescents (13-18 years) - **Dose**: Adult dosing guidelines apply. - **Maximum**: **10 mg** for single dose; total daily maximum up to **20 mg** in severe cases. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to phytonadione or any component. ### Common Adverse Effects - **Common (1-10%)**: Transient flushing, dizziness, rapid pulse, hypotension, taste perversion. - **Common (1-10%)**: Injection site pain, swelling, or tenderness. - **Serious but Rare**: Anaphylactoid reactions (with rapid IV administration), hyperbilirubinemia in neonates (rare with recommended doses). ### Key Drug Interactions - **Warfarin**: Vitamin K directly antagonizes the anticoagulant effect of warfarin. - **Effect**: Reduces INR, reverses anticoagulant effect. - **Clinical Significance**: Dose carefully to avoid over-reversal or under-reversal. - **Monitoring Requirement**: Monitor INR closely. ## Monitoring & Follow-up - **Before Treatment**: Baseline Prothrombin Time (PT) and International Normalized Ratio (INR). - **During Treatment**: Repeat PT/INR **6-8 hours** post-IV dose or **12-24 hours** post-PO dose. - **Clinical Signs**: Monitor for signs of bleeding (bruising, melena, hematuria) or thrombotic events. ## Clinical Pearls - 💡 **Timing**: Oral Vitamin K takes **6-24 hours** for full effect; IV onset is faster (within 2-6 hours). - 💡 **IV Administration**: Administer IV doses **SLOWLY** (over at least 30 minutes) to minimize risk of anaphylactoid reactions. - 💡 **Light Sensitivity**: Protect Vitamin K injectable solution from light. - 💡 **Pediatric Prophylaxis**: Universal Vitamin K prophylaxis at birth is crucial to prevent VKDB. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.