Usage
- Docaravimab is prescribed in combination with miromavimab (as Twinrab™) for post-exposure prophylaxis (PEP) of rabies. It is used in individuals who have been exposed to the rabies virus through a bite or scratch from an infected or suspected rabid animal. It is crucial in category III exposures as defined by the WHO.
- Pharmacological Classification: Rabies monoclonal antibody (mAb) cocktail/ Rabies Immunoglobulin (RIG)
- Mechanism of Action: Docaravimab and miromavimab bind to specific epitopes on the rabies virus glycoprotein, neutralizing the virus and preventing its entry into nerve cells. This provides passive immunity while the body develops an active immune response following rabies vaccination.
Alternate Names
- No alternate generic names are available for docaravimab itself. However, the combination product is known as Twinrab™ which contains docaravimab and miromavimab.
- Brand Name: Twinrab™
How It Works
- Pharmacodynamics: Docaravimab and miromavimab neutralize the rabies virus by binding to distinct sites (site III and site II, respectively) on the viral glycoprotein. This prevents the virus from binding to receptors on host cells, thereby inhibiting viral entry and subsequent replication.
- Pharmacokinetics: Administered intramuscularly (IM) or infiltrated around the wound, Twinrab™ achieves a high concentration of rabies virus neutralizing antibodies (RVNA) in the blood rapidly. The pharmacokinetics of individual components haven’t been extensively studied, but the cocktail provides immediate passive immunity. Elimination pathways are not specifically defined.
- Mode of Action: The antibodies sterically hinder the interaction between the rabies virus glycoprotein and host cell receptors, thus preventing viral fusion with the cell membrane and subsequent infection.
- Receptor Binding: Targets rabies virus glycoprotein.
- Elimination Pathways: Not explicitly stated.
Dosage
Standard Dosage
Adults:
40 IU/kg body weight administered once as soon as possible after exposure, ideally within 7 days of the first rabies vaccine dose. The minimum dose is 400 IU, and the maximum dose used in studies is 4280 IU.
Children:
40 IU/kg body weight, same as adults. Safety and efficacy have been established in children older than 5 years of age. For children under 5 years of age, usage should be under careful medical supervision.
Special Cases:
- Elderly Patients: No specific dose adjustments are mentioned in available studies.
- Patients with Renal Impairment: No dose adjustments are explicitly stated.
- Patients with Hepatic Dysfunction: No dose adjustments are mentioned.
- Patients with Comorbid Conditions: No specific recommendations are made, but clinical judgment is advised.
Clinical Use Cases
Twinrab™ is specifically indicated for post-exposure prophylaxis of rabies following potential rabies virus exposure (Category III). There are no recommendations for other clinical use cases.
Dosage Adjustments
- No explicit dose adjustments are provided for specific conditions. Clinical judgment is required in special populations.
Side Effects
Common Side Effects
Injection site reactions (pain, swelling, redness, tenderness, induration), low-grade fever, headache, nausea, malaise, arthralgia, myalgia.
Rare but Serious Side Effects
Severe allergic reactions (anaphylaxis), including difficulty breathing, facial or throat swelling, hives, and drop in blood pressure.
Long-Term Effects
No data available regarding long-term side effects.
Adverse Drug Reactions (ADR)
Severe allergic reactions (anaphylaxis).
Contraindications
No specific contraindications for rabies PEP with Twinrab™ are known. However, a history of severe hypersensitivity reactions to monoclonal antibodies should be considered. Pregnancy and breastfeeding require careful evaluation of risks and benefits by a physician.
Drug Interactions
No specific drug interactions are known. However, informing the physician about all concurrent medications is essential.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (US FDA classification - as of 2023-08-16). Animal studies show adverse effects, but potential benefits may outweigh risks in pregnant women.
- Fetal risks are not well-defined, but potential adverse effects observed in animal studies warrant caution.
- Drug excretion in breast milk is unknown.
- Consultation with a healthcare provider is essential for pregnant or breastfeeding women. The risk of rabies infection to the mother and potential transmission to the fetus/newborn should be carefully weighed against the potential risks of Twinrab™.
Drug Profile Summary
- Mechanism of Action: Neutralization of rabies virus by binding to viral glycoprotein.
- Side Effects: Injection site reactions, low-grade fever, allergic reactions.
- Contraindications: History of severe hypersensitivity to mAbs. Pregnancy and breastfeeding require careful consideration.
- Drug Interactions: No specific interactions known.
- Pregnancy & Breastfeeding: Category C; careful risk/benefit assessment is needed.
- Dosage: 40 IU/kg IM (or wound infiltration), single dose.
- Monitoring Parameters: Observe for allergic reactions, especially after administration. Monitor wound healing.
Popular Combinations
Twinrab™ is always given in combination with the rabies vaccine for post-exposure prophylaxis.
Precautions
- General Precautions: Assess for prior allergic reactions to similar products. Ensure appropriate storage and handling of the medication (2°C to 8°C).
- Specific Populations: Pregnant and breastfeeding women must consult a healthcare provider. Safe in children older than 5 years. Use with caution in children under 5 years.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Docaravimab/Twinrab™?
A: 40 IU/kg body weight, administered IM or infiltrated around the wound, as a single dose in conjunction with the rabies vaccine.
Q2: Can Twinrab™ be used in pregnant women?
A: Pregnancy is not an absolute contraindication. However, the risks and benefits should be carefully evaluated by a healthcare provider, as animal studies suggest some fetal risks.
Q3: How is Twinrab™ administered?
A: It is administered intramuscularly (IM) in the deltoid or anterolateral thigh, or it can be infiltrated around the bite wound.
Q4: Are there any known drug interactions with Twinrab™?
A: No specific drug interactions are known. It is essential to inform your physician about all medications, supplements, and herbal products the patient is taking.
Q5: What are the common side effects of Twinrab™?
A: Common side effects include local reactions at the injection site (pain, swelling, redness), mild fever, headache, and nausea.
Q6: What should I do if a patient experiences a severe allergic reaction after Twinrab™ administration?
A: Severe allergic reactions require immediate medical attention. Administer appropriate emergency treatment, including epinephrine if necessary.
Q7: Can Twinrab™ replace the rabies vaccine?
A: No. Twinrab™ provides immediate passive immunity, but it does not induce long-term protection. It is essential to administer the rabies vaccine concurrently to ensure long-lasting immunity.
Q8: What is the role of Twinrab™ in rabies post-exposure prophylaxis?
A: Twinrab™ provides immediate passive immunity by neutralizing the rabies virus while the body mounts its own immune response following vaccination. It is particularly crucial in Category III exposures.
Q9: How long does the protection from Twinrab™ last?
A: The protection offered by Twinrab™ is temporary, lasting for several weeks. The rabies vaccine is necessary to provide long-term immunity.
Q10: Is skin sensitivity testing required before administering Twinrab™?
A: No, skin sensitivity testing is not required before administering Twinrab™, unlike with some equine rabies immunoglobulins (ERIG).
