📋 Clinical Overview

Vitamin K is a fat-soluble vitamin essential for the synthesis of functional prothrombin and other clotting factors (II, VII, IX, X) and proteins involved in bone metabolism (osteocalcin, matrix Gla protein). The 10mg strength is a high-dose formulation primarily used for the treatment of significant vitamin K deficiency and reversal of over-anticoagulation from vitamin K antagonists like warfarin. In the Indian context, it is a critical agent for managing bleeding disorders and nutritional deficiencies.

💊 Dosage & Administration

Adult: For warfarin overdose: 2.5-10 mg orally; may repeat in 12-48 hrs based on INR. For deficiency: 10 mg orally daily for 3-5 days, then maintenance dose as needed.

Note: Administer orally with food, preferably a meal containing fats (e.g., milk, curd, nuts) to enhance absorption. Tablets should be swallowed whole with a glass of water. For patients with malabsorption, parenteral administration may be necessary.

⚠️ Contraindications

Hypersensitivity to phytonadione or any component of the formulation
Severe, life-threatening bleeding due to warfarin overdose (requires immediate reversal with Prothrombin Complex Concentrate (PCC) or Fresh Frozen Plasma (FFP); Vitamin K is an adjunct, not sole therapy)

🔬 Mechanism of Action

Vitamin K acts as an essential cofactor for the hepatic microsomal enzyme gamma-glutamyl carboxylase. This enzyme catalyzes the post-translational carboxylation of specific glutamic acid (Glu) residues to gamma-carboxyglutamic acid (Gla) residues on the precursor proteins of coagulation factors II, VII, IX, X, and proteins C, S, Z. The Gla residues are necessary for these factors to bind calcium ions, which is a critical step for their attachment to phospholipid surfaces and subsequent activation in the coagulation cascade.

🤕 Side Effects

Uncommon at therapeutic doses. Transient flushing sensation, altered taste.

🤰 Special Populations

Pregnancy: Category C (US FDA). Phytonadione crosses the placenta. Use only if clearly needed. High doses close to delivery may cause neonatal hyperbilirubinemia. Essential for preventing HDN.

Driving: No known effects on driving ability.

🔄 Drug Interactions

Warfarin / Acenocoumarol	Antagonizes anticoagulant effect, reduces INR. Can cause resistance.	Major
Broad-spectrum Antibiotics (e.g., Cephalosporins like Cefoperazone)	Can potentiate vitamin K deficiency by reducing gut flora that synthesize vitamin K2.	Moderate
Orlistat, Mineral Oil	Reduces absorption of fat-soluble vitamins including Vitamin K.	Moderate
Bile Acid Sequestrants (Cholestyramine, Colestipol)	Impairs absorption of Vitamin K.	Moderate
Salicylates (High Dose)	May potentiate hypoprothrombinemia.	Moderate

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