TheraRadar
Data updated: May 26, 2026

SYNAGIS (palivizumab)

Fusion Protein Inhibitors Trial Activity: Declining
Infectious Disease Approved 1998-06-19

SYNAGIS is indicated for the treatment of Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with a history of premature birth (less than or equal to 35 weeks gestational age) who are 6 months of age or younger at the beginning of RSV season.; Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with bronchopulmonary dysplasia (BPD) that required medical treatment within the previous 6 months and who are 24 months of age or younger at the beginning of RSV season.; Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with hemodynamically significant congenital heart disease (CHD) and who are 24 months of age or younger at the beginning of RSV season..

Source: FDA Label • SWEDISH ORPHAN • Respiratory Syncytial Virus Anti-F Protein Monoclonal Antibody

How SYNAGIS Works

Palivizumab is a recombinant humanized monoclonal antibody that acts as a respiratory syncytial virus (RSV) F protein inhibitor. By targeting the F protein on the surface of the virus, the drug provides specific anti-RSV activity to protect the lower respiratory tract. This mechanism prevents the virus from causing serious infection in vulnerable pediatric populations.

Development Insights

Merck Sharp & Dohme LLC conducting 1 trials (14%)
9 indications explored (Moderate)
respiratory syncytial virus infection (2 trials)
rsv infection (1 trials)
respiratory syncytial virus infections (1 trials)
3
Indications
--
Phase 3 Trials
1
Priority Reviews
27
Years on Market

Details

Status
Prescription
First Approved
1998-06-19
Routes
N/A
Dosage Forms
VIAL

Companies

Active Ingredient: PALIVIZUMAB

SYNAGIS Approval History

1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
Original
New Indication
New Form
Label Update
22 FDA actions from 1998 to 2017 · 2 indication expansions
May 2017 SUPPL
Label · Labeling
Mar 2014 SUPPL
Label · Labeling
Apr 2012 SUPPL
Efficacy

What SYNAGIS Treats

3 indications

SYNAGIS is approved for 3 conditions since its original approval in 1998. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with a history of premature birth (less than or equal to 35 weeks gestational age) who are 6 months of age or younger at the beginning of RSV season.
  • Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with bronchopulmonary dysplasia (BPD) that required medical treatment within the previous 6 months and who are 24 months of age or younger at the beginning of RSV season.
  • Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with hemodynamically significant congenital heart disease (CHD) and who are 24 months of age or younger at the beginning of RSV season.
Source: FDA Label

SYNAGIS Competitive Set

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Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.

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Clinical Trial Registry

7 trials
Trial Sponsor ID Phase Status Title
NCT04938830 SMART results posted 1654-007 MK-1654-007, jRCT2031210664 Ph 3 completed Clesrovimab (MK-1654) in Infants and Children at Increased Risk for Severe Respiratory Syncytial Virus (RSV) Disease (MK-1654-007)
NCT03959488 results posted D5290C00005 2019-000201-69 Ph 2, Ph 3 completed A Study to Evaluate the Safety of MEDI8897 for the Prevention of Medically Attended Respiratory Syncytial Virus(RSV) Lower Respiratory Track Infection (LRTI) in High-risk Children
NCT04540627 results posted MB05-P-01-20 Ph 1 completed Exploratory Study to Estimate the Prophylactic Efficacy of Palivizumab in Healthy Adult Participants Inoculated With RSV
NCT02968173 Synagis Russia results posted M15-539 2016-000221-39 Ph 3 completed A Study to Assess the Safety and Effectiveness of Palivizumab Administered to Children at High Risk of Severe Respiratory Syncytial Virus (RSV) Infection in the Russian Federation and the Republic of Belarus
NCT02442427 14302/14 Ph 3 completed "Palivizumab Therapy for RSV-bronchiolitis"
NCT01466062 results posted M12-420 Ph 3 completed Clinical Study of Palivizumab in Japanese Newborns, Infants and Young Children at the Age of 24 Months or Less With Immunocompromised Medical Conditions
NCT01006629 results posted W10-664 Ph 2, Ph 3 completed Palivizumab for Prevention of Severe Respiratory Syncytial Virus Infection in Russian Children
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Active Pipeline

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Ongoing clinical trials by development phase

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Key Completed Trials

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Completed studies with published results, ranked by significance

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

SYNAGIS FDA Label Details

Indications & Usage

FDA Label (PDF)

SYNAGIS is indicated for the treatment of Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with a history of premature birth (less than or equal to 35 weeks gestational age) who are 6 months of age or younger at the beginning of RSV season.; Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with bronchopulmonary dysplasia (BPD) that required medical treatment within the previous 6 months and who are 24 months of age or younger at the beginning of RSV season.; Prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in pediatric patients with hemodynamically significant congenital heart disease (CHD) and who are 24 months of age or younger at the beginning of RSV season..

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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.

How We Calculate These Metrics

Trial Activity Stage

Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.

Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.

  • Growth: High proportion of early-phase trials (Phase 1/2), active development
  • Expansion: Significant Phase 3 activity, approaching or pursuing approvals
  • Mature: Substantial Phase 4 post-marketing studies
  • Stable: Mixed phase distribution, steady development
  • Declining: Low active trial ratio, reduced R&D investment