Usage
- Fibrinogen is prescribed for the treatment of bleeding caused by hypofibrinogenemia (low levels of fibrinogen) in patients with congenital or acquired fibrinogen deficiency. It is crucial for blood clot formation and wound healing.
- Pharmacological Classification: Hemostatic agent, replacement factor.
- Mechanism of Action: Fibrinogen is converted to fibrin by thrombin during the coagulation cascade. Fibrin monomers polymerize to form a stable clot, which stops bleeding.
Alternate Names
- Factor I
- Fibrinogen Concentrate
- Brand Names: FIBRYGA, RiaSTAP, others (availability may vary by region).
How It Works
- Pharmacodynamics: Fibrinogen increases plasma fibrinogen levels, promoting hemostasis. Its primary effect is within the vascular system.
- Pharmacokinetics:
- Absorption: Administered intravenously, achieving immediate systemic availability.
- Metabolism: Primarily metabolized through normal fibrinolytic pathways.
- Elimination: The breakdown products of fibrin are cleared through multiple pathways. Half-life is 72-120 hours.
- Mode of Action: Thrombin cleaves fibrinogen to form fibrin monomers, which spontaneously polymerize into a fibrin clot. Factor XIIIa crosslinks these polymers, stabilizing the clot.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Not applicable.
- Elimination Pathways: Breakdown products are cleared through general metabolic processes.
Dosage
Standard Dosage
Adults:
- Acquired Fibrinogen Deficiency: 4 g IV. Further doses may be needed based on fibrinogen level and clinical response.
- Congenital Fibrinogen Deficiency: Dose calculation based on target and measured fibrinogen levels (see below).
Children:
- Acquired Fibrinogen Deficiency:
- Adolescents (≥12 years): 50 mg/kg IV.
- Children (<12 years): 70 mg/kg IV.
- Congenital Fibrinogen Deficiency: Dose calculation based on target and measured fibrinogen levels (see below).
Special Cases:
- Elderly Patients: Dosage adjustments may be needed based on individual patient factors like renal or hepatic impairment.
- Patients with Renal Impairment: Caution advised; dose adjustment based on the degree of impairment and clinical response may be necessary.
- Patients with Hepatic Dysfunction: Use with caution; monitor for thrombotic events.
- Patients with Comorbid Conditions: Individualized dosing may be required. Careful monitoring is recommended.
Clinical Use Cases
Dosing is guided by fibrinogen levels and clinical bleeding:
- Intubation/Surgical Procedures/Mechanical Ventilation/ICU Use/Emergency Situations: Dose according to acquired or congenital deficiency guidelines and clinical context. Target fibrinogen levels often higher in major bleeding or surgical settings.
Dosage Adjustments
- For congenital fibrinogen deficiency, when fibrinogen levels are known:
- Adults and adolescents (≥12 years): Dose (mg/kg) = [Target fibrinogen level (mg/dL) - Measured fibrinogen level (mg/dL)] x 1.8
- Children (<12 years): Dose (mg/kg) = [Target fibrinogen level (mg/dL) - Measured fibrinogen level (mg/dL)] x 1.4
- Target fibrinogen levels: 100 mg/dL for minor bleeding; 150 mg/dL for major bleeding.
- If fibrinogen level is unknown, 70 mg/kg IV is recommended. Monitor fibrinogen levels and adjust dose as needed.
Side Effects
Common Side Effects:
- Nausea, vomiting
- Fever, chills
Rare but Serious Side Effects:
- Allergic reactions (including anaphylaxis)
- Thromboembolic events (especially in patients with risk factors).
Long-Term Effects:
- No known long-term side effects associated with short-term use.
Adverse Drug Reactions (ADR):
- Anaphylaxis
- Myocardial infarction
- Stroke
- Pulmonary embolism
Contraindications
- Known hypersensitivity to fibrinogen or any component of the product.
Drug Interactions
- No significant drug interactions have been reported.
Pregnancy and Breastfeeding
- Data are limited. Use only if clearly needed.
- It is unknown if fibrinogen is excreted in breast milk.
Drug Profile Summary
- Mechanism of Action: Converted to fibrin by thrombin, forming blood clots.
- Side Effects: Nausea, vomiting, fever, chills, allergic reactions, thromboembolic events.
- Contraindications: Hypersensitivity.
- Drug Interactions: No known clinically significant interactions.
- Pregnancy & Breastfeeding: Use with caution if benefits outweigh risks.
- Dosage: See detailed dosage guidelines above.
- Monitoring Parameters: Fibrinogen levels, coagulation tests, signs of bleeding/thrombosis.
Popular Combinations
- Often used in conjunction with other hemostatic agents or blood products depending on the specific clinical scenario.
Precautions
- General Precautions: Monitor for thromboembolic complications, particularly in patients at risk.
- Specific Populations: Use with caution in elderly patients, patients with hepatic or renal impairment, pregnant and breastfeeding women.
- Lifestyle Considerations: No specific lifestyle considerations.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Fibrinogen?
A: The dosage varies depending on the indication (acquired vs. congenital deficiency), patient age, and whether the baseline fibrinogen level is known. See detailed dosage information above.
Q2: How is Fibrinogen administered?
A: Intravenously.
Q3: What are the serious side effects of Fibrinogen?
A: Thromboembolic events (stroke, myocardial infarction, pulmonary embolism) and allergic reactions, including anaphylaxis.
Q4: What should be monitored during Fibrinogen therapy?
A: Fibrinogen levels, coagulation tests (e.g., PT, aPTT, thrombin time), and clinical signs of bleeding or thrombosis.
Q5: Can Fibrinogen be used in pregnant women?
A: Data are limited. Use only if potential benefit outweighs the potential risk to the fetus.
Q6: How does Fibrinogen interact with other drugs?
A: No clinically significant drug interactions have been reported.
Q7: What is the difference between acquired and congenital fibrinogen deficiency?
A: Acquired deficiency develops later in life due to underlying conditions, whereas congenital deficiency is present from birth due to genetic defects.
Q8: How is the dose of Fibrinogen calculated for congenital deficiency?
A: The dose is calculated based on the target fibrinogen level, measured fibrinogen level, and age-dependent conversion factors. If the fibrinogen level is unknown, a standard dose of 70 mg/kg is recommended.
Q9: What is the role of viscoelastic testing in Fibrinogen dosing?
A: Viscoelastic tests, like thromboelastometry (TEM), can provide real-time assessment of clot formation and guide fibrinogen replacement therapy, particularly in acute bleeding situations.
