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Monday, July 28, 2025

Sotrovimab (Xevudy)


Generic Name: Sotrovimab
Brand Name: Xevudy
Drug Class: Monoclonal antibody – SARS-CoV-2 neutralizing agent
Molecular Type: Recombinant human IgG1-kappa monoclonal antibody
Formulation: Concentrate for intravenous infusion
Available Strength: 500 mg/8 mL (62.5 mg/mL) vial
Route of Administration: Intravenous infusion
Primary Use: Treatment of mild to moderate COVID-19 in high-risk patients not requiring oxygen therapy

Sotrovimab is a monoclonal antibody targeting the spike protein of SARS-CoV-2. It was developed for early outpatient use to reduce progression of COVID-19 and prevent hospitalization in high-risk individuals.

2. Mechanism of Action

Sotrovimab binds to a conserved epitope on the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. This prevents the virus from attaching to the human ACE2 receptor, blocking viral entry into host cells. Additionally, it promotes immune-mediated clearance of infected cells through antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP). The target epitope is relatively conserved across coronaviruses, making Sotrovimab less vulnerable to certain spike mutations.

3. Pharmacological Properties

Onset of Action: Within hours of infusion
Duration of Effect: Several weeks due to extended half-life
Bioavailability: 100% (intravenous)
Metabolism: Catabolized via proteolytic degradation pathways typical of IgG antibodies
Elimination Half-life: Approximately 49 days
Distribution: Broad tissue penetration including respiratory tract
Excretion: Not eliminated via renal or hepatic pathways

4. Indications

  • Treatment of mild to moderate COVID-19 in adults and adolescents (≥12 years old and ≥40 kg)

  • Patient must be at high risk for progression to severe disease, hospitalization, or death

  • Initiate therapy as soon as possible and within 5 days of symptom onset

  • Not authorized for use in hospitalized patients requiring oxygen or mechanical ventilation due to COVID-19

5. Dosage and Administration

Dose:
500 mg as a single intravenous infusion

Infusion Time:
Over 15 to 30 minutes depending on dilution volume

Preparation:
Dilute 8 mL (500 mg) of concentrate in 50 mL or 100 mL of 0.9% sodium chloride solution. Do not shake. Gently invert to mix. Administer immediately after preparation or store under recommended conditions.

Storage:
Store vials at 2–8°C. Protect from light. Diluted solution stable for 6 hours at room temperature or 24 hours in refrigerator.

Monitoring:
Observe patient for at least 1 hour after infusion for hypersensitivity or infusion-related reactions.

6. Contraindications

  • Known hypersensitivity to sotrovimab or excipients

  • Previous severe allergic reaction to monoclonal antibodies

  • Patients already hospitalized with severe or critical COVID-19

  • Not intended for use in patients requiring supplemental oxygen due to COVID-19

7. Precautions

  • Risk of serious infusion-related reactions, including anaphylaxis

  • Use with caution in patients with a history of hypersensitivity to biologics

  • Must be administered in a setting equipped to manage anaphylaxis

  • Efficacy is dependent on circulating SARS-CoV-2 variants; treatment should align with current variant susceptibility

  • Avoid delayed administration beyond 5 days from symptom onset

  • Limited data in pregnancy and lactation; use only if potential benefits outweigh risks

8. Use in Special Populations

Elderly:
No dosage adjustment needed. Safety profile similar to younger adults.

Renal Impairment:
No adjustment necessary. Not eliminated via kidneys.

Hepatic Impairment:
No dosage changes required.

Pediatrics:
Approved for use in adolescents ≥12 years and ≥40 kg. Not studied in younger children.

Pregnancy:
No adequate data in pregnant women. Theoretical risk due to immunoglobulin crossing the placenta in later trimesters.

Lactation:
Unknown whether sotrovimab is excreted in human milk. Minimal systemic absorption expected in the nursing infant.

9. Adverse Effects

Common (>1%):

  • Rash

  • Nausea

  • Diarrhea

  • Headache

  • Dizziness

  • Chills

  • Fatigue

  • Infusion site reactions (pain, erythema, swelling)

Less Common (<1%):

  • Hypotension

  • Chest discomfort

  • Pruritus

  • Fever

  • Facial swelling

Serious:

  • Anaphylaxis

  • Severe infusion-related reactions

  • Hypersensitivity reactions requiring medical attention

  • Potential risk of antibody-resistant mutations in immunocompromised patients

10. Drug Interactions

  • No known pharmacokinetic interactions

  • Does not involve cytochrome P450 enzymes or transporter systems

  • May be co-administered with COVID-19 antivirals or corticosteroids, if clinically indicated

  • Live vaccines should be delayed for at least 90 days after monoclonal antibody administration due to potential blunting of vaccine response

11. Clinical Monitoring

During Infusion:

  • Continuous observation for early signs of infusion-related reactions

  • Monitor vital signs (heart rate, blood pressure, respiratory rate, oxygen saturation)

Post Infusion:

  • Observe for 1 hour post-infusion

  • Watch for signs of delayed hypersensitivity

Laboratory Monitoring:

  • Not routinely required

  • Consider viral load tracking in research or high-risk patients

  • Evaluate renal function and inflammatory markers if clinical status deteriorates

12. Resistance and Variants

  • Sotrovimab was originally effective against Alpha, Beta, Gamma, and early Delta variants

  • Retained partial activity against Omicron BA.1 but reduced neutralization against BA.2, BA.4, BA.5 and later variants

  • Widespread resistance led to withdrawal of authorization in many jurisdictions

  • Clinicians must ensure sotrovimab is being used only when circulating variants are known to be susceptible

13. Discontinuation and Withdrawal

  • Sotrovimab was temporarily authorized during early pandemic phases

  • Emergency Use Authorizations were revoked in several countries due to emerging resistance

  • Currently no longer recommended as first-line monoclonal antibody therapy in regions dominated by Omicron subvariants or newer lineages

  • Replacement therapies now include newer monoclonal antibodies or oral antivirals with broader efficacy

14. Summary Points of Care Use

  • Administer within 5 days of symptom onset

  • Reserved for non-hospitalized high-risk patients

  • Contraindicated in advanced or critical illness

  • Must assess variant susceptibility before prescribing

  • Monitor closely during and after infusion

  • Educate patients about signs of allergic reaction

  • Avoid routine use in areas with resistant viral strains

  • Evaluate need for alternative antiviral options in evolving epidemiologic context



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