PHYTOZ

Indications

• Vitamin K deficiency
• Anticoagulant reversal
• Prophylaxis of vitamin K deficiency in newborns
• Malabsorption syndromes

Mechanism of action

Phytomenadione functions as a cofactor for the enzyme gamma-glutamyl carboxylase, which is essential for the post-translational modification of certain proteins. This modification allows these proteins to bind calcium ions, which is critical for their activity in the coagulation cascade. By facilitating the synthesis of vitamin K-dependent clotting factors in the liver, phytomenadione helps to restore normal blood coagulation processes.

Pharmacodynamics

Phytomenadione is involved in the carboxylation of specific glutamic acid residues on clotting factors, which is necessary for their activity. The vitamin's role in the coagulation cascade is vital for hemostasis, the process that prevents excessive bleeding when blood vessels are injured. Additionally, it contributes to bone health by regulating the calcium-binding properties of osteocalcin, a protein essential for bone mineralization.

Pharmacokinetics

After oral administration, phytomenadione is absorbed in the intestine, with peak plasma concentrations occurring within 1 to 4 hours. It is transported in the bloodstream bound to lipoproteins, and its distribution is primarily to the liver, where it exerts its effects. The elimination half-life of phytomenadione ranges from 1 to 2 hours, and it is metabolized primarily in the liver. The vitamin is excreted in bile and urine, and its fat-soluble nature allows for its storage in the liver and fatty tissues, which can serve as a reservoir during periods of deficiency.

Contra-indications

• Hypersensitivity to phytomenadione or any of its components
• Severe liver disease
• Active bleeding disorders
• Coagulopathy due to anticoagulant therapy

Adverse effects

• Allergic reactions
• Hypersensitivity reactions
• Injection site reactions
• Flushing
• Dizziness
• Nausea
• Abdominal pain

Interactions

• Anticoagulants (e.g., warfarin) - may reduce the effect of anticoagulants
• Other vitamin K antagonists - can lead to increased risk of bleeding
• Cholestyramine - may affect absorption of vitamin K
• Antibiotics - may alter gut flora and affect vitamin K synthesis

Precautions

• Use with caution in patients with liver impairment
• Monitor patients on anticoagulants closely when initiating or adjusting doses
• Assess for potential vitamin K deficiency in patients with malabsorption syndromes

Pregnancy

Phytomenadione is generally considered safe during pregnancy when used as prescribed, as it is important for fetal development of blood coagulation.

Breast-feeding

Phytomenadione is excreted in breast milk, but it is considered safe for use during breastfeeding.

Storage

Store in a cool, dry place away from direct sunlight. Protect from light.

Formulations

• Injection solution
• Oral tablets
• Capsules