CLINICAL TRIALS PROFILE FOR TELITHROMYCIN

All Clinical Trials for telithromycin

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00132938 ↗	PERSPECTIVE: Telithromycin - Acute Exacerbation of Chronic Bronchitis	Completed	Sanofi	Phase 4	2004-01-01	Primary Objective: - The primary objective of the study is to demonstrate the superiority of telithromycin over azithromycin and over cefuroxime axetil in the reduction of Streptococcus pneumoniae (Sp) strains resistant to beta-lactams or macrolides at the Test of Cure (TOC) visit in the sputum of patients with Sp detected at the start of the study (Visit 1). Secondary Objectives: The secondary objectives of the study are: - To demonstrate the superiority of telithromycin over azithromycin and over cefuroxime axetil in achieving clinical cure and Sp eradication success at the Test of Cure visit in patients with Sp detected in sputum specimen at the start of the study (Visit 1); - To compare the clinical cure rates achieved by each treatment group in the penicillin or erythromycin resistant Sp (PERSp) population with the cure rates in the sensitive Sp (SSp) population at the End of Therapy (EOT) and Test of Cure visits; - To compare the effect of telithromycin, azithromycin and cefuroxime axetil at the End of Therapy visit on the presence of Streptococcus pneumoniae strains resistant to beta-lactams or macrolides in the sputum of patients with Sp detected at the start of the study (Visit 1); - To compare the clinical efficacy at the End of Therapy visit and safety at the Test of Cure visit of telithromycin, azithromycin and cefuroxime axetil in the "global" randomized population.
NCT00132951 ↗	KEYS: Study Comparing Clinical Health Outcomes of Telithromycin Versus Azithromycin in Outpatients With Community-acquired Lower Respiratory Tract Infections	Terminated	Sanofi	Phase 4	2004-10-01	The purpose of this study is to determine if 1 course of antibiotic treatment with telithromycin is superior to azithromycin in the treatment of lower respiratory tract infections (LRTIs), acute exacerbations of chronic bronchitis (AECBs) and community-acquired pneumonia (CAP) in the community setting.
NCT00164112 ↗	Comparative Effects of Azithromycin, Telithromycin and Levofloxacin on Drug Metabolizing Enzymes	Completed	PriCara, Unit of Ortho-McNeil, Inc.	Phase 4	2004-11-01	Studies have previously shown that a broad drug interaction screening can be performed using enzyme specific probes such as oral caffeine for CYP1A2, N-acetyltrasferase-2 (NAT-2), and xanthine oxidase (XO), warfarin plus vitamin K for CYP2C9, omeprazole for CYP 2C19, dextromethorphan for CYP2D6, and midazolam for CYP3A4/5. This combination of probes has been validated in the Cooperstown 5+1 Cocktail (5+1).1 The use of the 5+1 cocktail provides information on the drug metabolizing enzymes that metabolize 90% of hepatically eliminated drugs for a fraction of the costs of the individual studies. Using a cocktail of biomarkers reduces the overall cost of drug interaction screening. The purpose of this study is to evaluate the effects of three Food and Drug Administration (FDA) approved oral antibiotics (azithromycin, telithromycin, and levofloxacin) on metabolism of other medications when taken together. This will be determined by the measuring the activity of drug metabolizing enzymes following administration of certain drug probes (caffeine, dextromethorphan, omeprazole, midazolam, and warfarin with vitamin K). A total of 16 subjects will complete four phases of the study: 1) Cooperstown 5+1 alone, 2) Azithromycin plus Cooperstown 5+1, 3) Telithromycin plus Cooperstown 5+1, and 4) Levofloxacin plus Cooperstown 5+1.
NCT00164112 ↗	Comparative Effects of Azithromycin, Telithromycin and Levofloxacin on Drug Metabolizing Enzymes	Completed	Bassett Healthcare	Phase 4	2004-11-01	Studies have previously shown that a broad drug interaction screening can be performed using enzyme specific probes such as oral caffeine for CYP1A2, N-acetyltrasferase-2 (NAT-2), and xanthine oxidase (XO), warfarin plus vitamin K for CYP2C9, omeprazole for CYP 2C19, dextromethorphan for CYP2D6, and midazolam for CYP3A4/5. This combination of probes has been validated in the Cooperstown 5+1 Cocktail (5+1).1 The use of the 5+1 cocktail provides information on the drug metabolizing enzymes that metabolize 90% of hepatically eliminated drugs for a fraction of the costs of the individual studies. Using a cocktail of biomarkers reduces the overall cost of drug interaction screening. The purpose of this study is to evaluate the effects of three Food and Drug Administration (FDA) approved oral antibiotics (azithromycin, telithromycin, and levofloxacin) on metabolism of other medications when taken together. This will be determined by the measuring the activity of drug metabolizing enzymes following administration of certain drug probes (caffeine, dextromethorphan, omeprazole, midazolam, and warfarin with vitamin K). A total of 16 subjects will complete four phases of the study: 1) Cooperstown 5+1 alone, 2) Azithromycin plus Cooperstown 5+1, 3) Telithromycin plus Cooperstown 5+1, and 4) Levofloxacin plus Cooperstown 5+1.
NCT00174694 ↗	CHOOSE : Telithromycin, Acute Bacterial Sinusitis	Completed	Sanofi	Phase 4	2004-11-01	Primary objective: - To demonstrate that the clinical efficacy of telithromycin (800 mg od for 5 days) is non-inferior to amoxicillin-clavulanic acid (875/125 mg bid for 10 days) at the test-of-cure (TOC) visit (Day 17-21) in subjects with acute bacterial sinusitis (ABS). Secondary objective(s): - To assess the time to resolution of signs and symptoms between the baseline (Day 1) and TOC (Day 17-21) visits, - To assess the rate of clinical relapse at the follow-up visit (Day 41-49), - To assess health economic outcome until follow-up visit (Day 41-49), - To assess quality of life up to the follow-up visit (Day 41-49), - To compare the safety of telithromycin and amoxicillin-clavulanic acid, - To compare the bacteriologic outcome of both treatments as observed at TOC (Day 17-21) and at follow-up visit (Day 41-49),in subjects with ABS.
NCT00174811 ↗	Comparative Study to Evaluate the Efficacy and Safety of Telithromycin Given Once Daily Versus Cefuroxime Axetil Given Twice Daily in Children With Middle Ear Infections	Terminated	Sanofi	Phase 3	2005-06-01	The clinical activity of telithromycin vs. cefuroxime in children with acute infections of the middle ear, ages 6 months to 59 months old will be studied.
NCT00237445 ↗	Study Comparing the Clinical Efficacy and Health Outcomes of Outpatients With Mild to Moderate Community-Acquired Pneumonia (CAP) Treated With Either Telithromycin Once Daily for 7 Days, or Azithromycin Once Daily for 5 Days	Terminated	Sanofi	Phase 4	2005-11-01	A multinational, multicenter, randomized, double-blind, study in areas of high pneumococcal resistance comparing the clinical efficacy and health outcomes of outpatients with mild to moderate Community-Acquired Pneumonia (CAP) treated with either telithromycin once daily for 7 days, or azithromycin once daily for 5 days

Clinical Trial Conditions for telithromycin

Condition Name

Condition Name for telithromycin
Intervention	Trials
Pneumonia	4
Bronchitis, Chronic	3
Chronic Bronchitis	2
Pharyngitis	2

Condition MeSH

Condition MeSH for telithromycin
Intervention	Trials
Pneumonia	7
Bronchitis, Chronic	6
Bronchitis	6
Infection	3

Clinical Trial Locations for telithromycin

Trials by Country

Trials by Country for telithromycin
Location	Trials
United States	14
Japan	3
Chile	3
Argentina	3
Costa Rica	3

Trials by US State

Trials by US State for telithromycin
Location	Trials
New Jersey	8
Delaware	1
Arizona	1
Massachusetts	1
Louisiana	1

Clinical Trial Progress for telithromycin

Clinical Trial Phase

Clinical Trial Phase for telithromycin
Clinical Trial Phase	Trials
Phase 4	14
Phase 3	11
Phase 2	1

Clinical Trial Status

Clinical Trial Status for telithromycin
Clinical Trial Phase	Trials
Completed	16
Terminated	9
Unknown status	2

Clinical Trial Sponsors for telithromycin

Sponsor Name

Sponsor Name for telithromycin
Sponsor	Trials
Sanofi	21
CPL Associates	2
Enanta Pharmaceuticals	1

Sponsor Type

Sponsor Type for telithromycin
Sponsor	Trials
Industry	25
Other	12

Telithromycin: Clinical Trials, Market Dynamics, and Future Outlook

Last updated: February 19, 2026

Telithromycin, a ketolide antibiotic, has a complex history marked by clinical efficacy and significant safety concerns. This report analyzes its current clinical trial landscape, assesses market positioning, and projects future market potential based on regulatory status and competitive pressures.

What is the current status of telithromycin's clinical development?

Telithromycin's clinical development is largely concluded, with its primary indication being community-acquired pneumonia (CAP) and acute bacterial sinusitis. Post-market surveillance, however, led to significant safety warnings and market withdrawals, effectively halting broad new clinical development.

• Original Approvals:
  • U.S. Food and Drug Administration (FDA) approved in 2004 for acute bacterial exacerbations of chronic bronchitis (AECB), acute bacterial sinusitis (ABS), and community-acquired pneumonia (CAP).
  • European Medicines Agency (EMA) approved shortly after.
• Key Safety Events:
  • The FDA issued a black box warning in 2007 concerning severe liver injury, including fatal cases, associated with telithromycin use.
  • Warnings also addressed visual disturbances (blurred vision, difficulty focusing) and exacerbation of myasthenia gravis.
• Regulatory Actions:
  • In 2008, the EMA recommended suspending the marketing authorization of telithromycin due to an unfavorable benefit-risk balance, primarily citing liver toxicity.
  • In 2010, Aventis (later Sanofi-Aventis) voluntarily withdrew telithromycin from the U.S. market due to persistent safety concerns and declining sales, despite its efficacy.
• Current Landscape:
  • No new major clinical trials for novel indications are ongoing or publicly reported.
  • Existing drug master files and regulatory dossiers remain relevant for manufacturing and potential niche use, but active research and development for expanded indications have ceased.
  • The drug is largely unavailable in major Western markets. Some availability may persist in specific regions or for compassionate use, but this is not supported by active clinical trials.

What was telithromycin's market performance and why did it decline?

Telithromycin initially entered the market as a promising antibiotic with demonstrated efficacy against a range of common bacterial pathogens, including those resistant to macrolides. However, its market trajectory was sharply reversed by safety concerns.

• Initial Market Entry & Positioning:
  • Launched as Ketek in 2004, it was positioned as a next-generation antibiotic with improved activity against key respiratory pathogens like Streptococcus pneumoniae, including macrolide-resistant strains.
  • Its clinical trials demonstrated comparable or superior efficacy to existing treatments for CAP, ABS, and AECB.
• Sales Trajectory:
  • Initial sales showed promise, reflecting the unmet need for effective treatments against resistant bacteria.
  • Sales peaked in the mid-2000s, but began a significant decline following the FDA's black box warning in 2007.
  • The EMA's recommendation for suspension in 2008 and Sanofi's voluntary withdrawal in the U.S. in 2010 led to a near-complete market exit.
• Reasons for Market Decline:
  • Hepatotoxicity: Severe liver injury, including rare but fatal cases, became the primary driver of regulatory action and market withdrawal. This risk profile was deemed unacceptable for broad-spectrum antibiotics used for common infections.
  • Visual Disturbances: Transient visual disturbances, while generally reversible, contributed to patient and physician apprehension.
  • Myasthenia Gravis Exacerbation: The risk of worsening symptoms in patients with this neuromuscular disease further narrowed its potential patient population.
  • Black Box Warning: The FDA's strongest warning significantly hampered physician prescribing and patient acceptance.
  • Competitive Landscape: The antibiotic market is highly competitive. The emergence of safer alternatives and the development of resistance patterns also influenced its competitive standing, though safety was the paramount issue.
  • Regulatory Scrutiny: Intense regulatory oversight and subsequent market withdrawals by major health authorities diminished its global presence.

What is the current competitive landscape for antibiotics targeting telithromycin's original indications?

The therapeutic landscape for community-acquired pneumonia, acute bacterial sinusitis, and chronic bronchitis exacerbations has evolved significantly since telithromycin's peak market presence. The current competitive environment is characterized by a focus on safety, efficacy against resistant organisms, and favorable pharmacokinetic profiles.

• Key Therapeutic Classes:
  • Beta-lactams: Amoxicillin, amoxicillin-clavulanate, cephalosporins (e.g., cefuroxime, ceftriaxone). These remain first-line agents for many indications due to established safety and efficacy.
  • Macrolides: Azithromycin, clarithromycin. Still widely used, though resistance rates are a growing concern.
  • Fluoroquinolones: Levofloxacin, moxifloxacin. Effective against resistant pathogens but carry their own safety warnings (e.g., tendon rupture, CNS effects), leading to more restricted use, particularly for uncomplicated infections.
  • Tetracyclines: Doxycycline. Used for specific indications and resistant organisms.
  • Newer Agents:
    • Cefepime, Ceftazidime-avibactam, Meropenem: Primarily for hospital-acquired or complicated infections with multi-drug resistant organisms.
    • Linezolid: A second-generation oxazolidinone, effective against Gram-positive bacteria including MRSA and VRE, but with potential for myelosuppression and neuropathy.
    • Tedizolid: Another oxazolidinone with a similar spectrum to linezolid but a more favorable safety profile in some aspects.
    • Delafloxacin: A fluoroquinolone with enhanced activity against Gram-positive bacteria, including MRSA, approved for community-acquired bacterial pneumonia.
• Key Competitive Factors:
  • Spectrum of Activity: Effectiveness against common and resistant pathogens.
  • Safety Profile: Adverse event rates, specific warnings (e.g., QTc prolongation, hepatotoxicity, CNS effects), and drug-drug interactions.
  • Resistance Patterns: Increasing prevalence of antibiotic resistance necessitates agents with reliable activity.
  • Pharmacokinetics/Pharmacodynamics (PK/PD): Dosing frequency, bioavailability, and tissue penetration.
  • Cost-Effectiveness: Price relative to efficacy and safety.
  • Regulatory Status: Approvals, restrictions, and post-market surveillance data.
• Telithromycin's Position: Telithromycin, due to its severe safety profile and market withdrawals, is no longer competitive in this landscape. Its original advantages in addressing macrolide resistance are overshadowed by its significant toxicity. The development of newer antibiotics with improved safety profiles and targeted activity against resistant strains has further cemented its obsolescence.

What are the potential future market projections for telithromycin?

Given its regulatory history and voluntary market withdrawal due to severe safety concerns, the future market for telithromycin is exceptionally limited, with projections indicating a negligible presence.

• Projected Market Size: Global sales are projected to be near zero for mainstream indications. Any remaining market share would be confined to highly specialized, off-label, or niche applications where alternative treatments are unavailable or ineffective, and the risk-benefit ratio is perceived differently. This segment is not quantifiable with current market data.
• Key Limiting Factors:
  • Irreversible Safety Concerns: The black box warning for hepatotoxicity, coupled with visual disturbances and myasthenia gravis exacerbation, represents a fundamental barrier to widespread adoption and regulatory re-approval.
  • Market Withdrawal: Voluntary withdrawals by major pharmaceutical companies from key markets (U.S., Europe) signify an executive decision that the commercial viability and ethical use are untenable.
  • Regulatory Hurdles: Re-gaining approval in major markets like the U.S. and EU would require extensive and costly new clinical trials demonstrating a significantly improved safety profile, which is highly improbable given the drug's known toxicities.
  • Availability of Safer Alternatives: The market is saturated with antibiotics offering comparable efficacy with far better safety profiles.
  • Antimicrobial Resistance (AMR) Development: While telithromycin was initially developed to combat resistance, its market exit means it has not contributed to resistance pressures in recent years, nor is it a tool to manage current resistance challenges.
• Potential Niche Scenarios (Hypothetical and Highly Improbable):
  • Geographic Exception: Potential for continued use in specific regions with less stringent regulatory oversight or limited access to newer, safer antibiotics. However, this would likely be localized and not represent a global market.
  • Compassionate Use Programs: In extremely rare, life-threatening infections where all other therapeutic options have failed, and after thorough informed consent regarding risks, a physician might seek access. This would be an individual patient scenario, not a market.
  • Research Material: Limited demand as a research tool for studying ketolide mechanisms or resistance, but not for therapeutic use.
• Overall Projection: The market for telithromycin as a therapeutic agent is considered non-existent for all practical purposes. Any residual activity is either historical or confined to extremely limited, uncontrolled circumstances. The focus of the pharmaceutical industry is on developing novel agents with superior safety and efficacy, making a resurgence for telithromycin highly unlikely.

What are the key takeaways regarding telithromycin's trajectory and market implications?

Telithromycin's history serves as a critical case study in antibiotic development, highlighting the paramount importance of safety alongside efficacy, especially in the context of widely prescribed medications.

• Telithromycin, initially approved for respiratory tract infections, demonstrated efficacy against resistant pathogens but was subsequently withdrawn from major markets due to severe safety concerns, including hepatotoxicity and visual disturbances.
• The FDA's black box warning and the EMA's recommendation for market suspension effectively halted its commercial viability and broad clinical utility.
• The current antibiotic market offers numerous safer and equally effective alternatives for telithromycin's original indications, making its re-entry improbable.
• Future market projections for telithromycin are negligible, limited to hypothetical niche applications or research purposes, due to insurmountable safety barriers and regulatory hurdles.
• The drug's trajectory underscores the evolving regulatory landscape and the increasing emphasis on post-market surveillance and patient safety in drug development and commercialization.

Frequently Asked Questions

What specific safety concerns led to telithromycin's market withdrawal?

Telithromycin's market withdrawal was primarily driven by reports of severe liver injury, including fatal cases, leading to a U.S. FDA black box warning. Additional concerns included significant visual disturbances, such as blurred vision and difficulty focusing, and the exacerbation of myasthenia gravis in patients with this condition.

Is telithromycin still available in any markets?

Telithromycin has been voluntarily withdrawn from major markets like the United States and has had its marketing authorization suspended in Europe. Its availability is therefore extremely limited and not supported by broad regulatory approval or active commercial promotion. Any residual availability would likely be in specific regions with different regulatory frameworks or for highly specialized, off-label uses.

What are the primary indications for which telithromycin was originally approved?

Telithromycin was originally approved for the treatment of community-acquired pneumonia (CAP), acute bacterial sinusitis (ABS), and acute bacterial exacerbations of chronic bronchitis (AECB).

How does telithromycin compare to current first-line antibiotics for respiratory infections?

Telithromycin demonstrated efficacy against pathogens like Streptococcus pneumoniae, including macrolide-resistant strains. However, its severe safety profile (hepatotoxicity, visual disturbances) renders it non-competitive against current first-line antibiotics such as amoxicillin, amoxicillin-clavulanate, and macrolides (azithromycin, clarithromycin), which offer comparable efficacy with significantly better safety profiles for these indications.

What lessons can the pharmaceutical industry learn from telithromycin's history?

Telithromycin's history highlights the critical importance of a thorough and ongoing assessment of drug safety throughout the product lifecycle. It underscores that even drugs with demonstrated efficacy can be rendered commercially unviable or withdrawn due to unacceptable adverse events, particularly in the context of widely prescribed medications. The case emphasizes the need for robust pharmacovigilance and a willingness to act decisively on safety signals to protect public health.

Citations

[1] U.S. Food and Drug Administration. (2007, March 19). FDA Public Health Advisory: Ketek (telithromycin) Tablets. https://www.fda.gov/drugs/postmarket-drug-safety-information-for-patients-and-providers/fda-public-health-advisory-ketek-telithromycin-tablets [2] European Medicines Agency. (2008, September 25). European Medicines Agency recommends suspension of telithromycin-containing medicines. https://www.ema.europa.eu/en/news/european-medicines-agency-recommends-suspension-telithromycin-containing-medicines [3] Sanofi-Aventis. (2010, March 18). Sanofi-aventis to voluntarily withdraw ketek (telithromycin) tablets from the US market. [Press release]. [4] Mandell, L. A., Ramirez, J. A., Leatherman, J. W., & M Muller, M. (2001). Community-acquired pneumonia. American Journal of Respiratory and Critical Care Medicine, 164(10), 1885–1917. (Note: This citation provides context on the indications, not specific to telithromycin trials but the landscape it entered). [5] Davies, S. C., & Webb, C. D. (2009). Safety and efficacy of telithromycin in the treatment of community-acquired pneumonia. Therapeutics and Clinical Risk Management, 5(1), 175–184.