Phytonadione, also known as Vitamin K₁, is a life-saving drug used to correct bleeding disorders caused by vitamin K deficiency and to reverse warfarin effects. It is a high-yield topic in pharmacology, medicine, pediatrics, and surgery, especially for MBBS, nursing, pharmacy, and paramedical students.
What Is Phytonadione?
Phytonadione is the natural form of vitamin K (Vitamin K₁) obtained from plant sources. It plays a crucial role in blood coagulation.
Quick Drug Profile
| Feature | Details |
|---|---|
| Generic name | Phytonadione |
| Common names | Vitamin K₁ |
| Brand names | AquaMEPHYTON, Mephyton |
| Drug class | Fat-soluble vitamin |
| Main role | Synthesis of clotting factors |
| Routes | Oral, IM, IV |
Why Vitamin K Is Essential
Vitamin K is required for the synthesis of coagulation factors in the liver.
Vitamin K–Dependent Factors (Exam Favorite)
1. Factor II (Prothrombin)Without vitamin K, these factors are inactive, leading to bleeding.
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Mechanism of Action of Phytonadione (Very High-Yield)
Phytonadione acts as a cofactor in γ-carboxylation of clotting factors.
Step-by-Step Mechanism
1. Phytonadione enters the liverOne-Line Exam Answer
Vitamin K is required for γ-carboxylation of clotting factors II, VII, IX, and X
Clinical Uses of Phytonadione
1. Vitamin K Deficiency
- Malnutrition
- Fat malabsorption
- Prolonged antibiotic use
- Liver disease (partial benefit)
2. Warfarin Overdose (Very Important)
- Reverses anticoagulant effect of warfarin
- Restores clotting factor synthesis
Key Concept:
Warfarin blocks vitamin K recycling → phytonadione overcomes this block.
3. Hemorrhagic Disease of the Newborn
- Newborns have low vitamin K levels
- Prevents life-threatening bleeding
Routine IM vitamin K at birth is standard practice.
4. Obstructive Jaundice
- Fat-soluble vitamin absorption impaired
- Parenteral vitamin K needed
Routes of Administration
| Route | Notes |
|---|---|
| Oral | Preferred if absorption is normal |
| IM | Common in newborns |
| IV | Emergency use (slow infusion only) |
Rapid IV injection may cause anaphylactoid reactions.
Pharmacokinetics (Simplified)
- Fat-soluble
- Absorbed with bile salts
- Stored in liver
- Onset of action: 6–12 hours
- Full effect: 24 hours
Important: Not useful for immediate bleeding control.
Adverse Effects
Common
- Injection site pain
- Flushing
- Taste disturbance (oral)
Serious (Rare)
- Anaphylactoid reaction (IV use)
- Hypotension
- Bronchospasm
Contraindications & Precautions
Avoid or use cautiously in:
- Known hypersensitivity
- Severe liver failure (limited response)
- Neonates (dose must be precise)
Phytonadione vs Fresh Frozen Plasma (FFP)
| Feature | Phytonadione | FFP |
|---|---|---|
| Onset | Slow | Immediate |
| Mechanism | New clotting factor synthesis | Provides ready factors |
| Use | Warfarin reversal (stable) | Life-threatening bleeding |
Exam Tip:
Acute bleeding + warfarin → FFP + Vitamin K
Vitamin K Forms (Exam Table)
| Type | Name | Source |
|---|---|---|
| K₁ | Phytonadione | Plants |
| K₂ | Menaquinone | Gut bacteria |
| K₃ | Menadione | Synthetic (toxic, not used) |
Important Exam-Oriented Points
- Does not dissolve clots
- Corrects prolonged PT/INR
- Takes time to act
- Ineffective if liver is unable to synthesize factors
Easy Memory Tricks
Clotting Factors
“1972 – K was born”
(II, VII, IX, X)
Warfarin Link
“Warfarin blocks K → Give K back”
FAQs
1. What is phytonadione?
Phytonadione is vitamin K₁, essential for clotting factor synthesis.
2. Which clotting factors depend on vitamin K?
Factors II, VII, IX, X and proteins C and S.
3. Why is vitamin K given to newborns?
To prevent hemorrhagic disease of the newborn.
4. Is phytonadione an anticoagulant?
No, it promotes clotting by enabling clotting factor synthesis.
5. How does phytonadione reverse warfarin?
It restores vitamin K–dependent clotting factor synthesis.
6. Why is IV vitamin K given slowly?
Rapid injection may cause severe anaphylactoid reactions.
7. Can vitamin K stop active bleeding immediately?
No, it takes several hours to act.
8. What lab value improves after vitamin K?
Prothrombin time (PT) and INR.
9. Is vitamin K fat-soluble?
Yes, absorption requires bile salts.
10. What is the brand name of phytonadione?
AquaMEPHYTON, Mephyton.
