Last reviewed 2026-06-01 · How we verify

BAY 77-1931

Bayer · Phase 2 active Small molecule Under review

BAY 77-1931 is a Direct thrombin inhibitor Small molecule drug developed by Bayer. It is currently in Phase 2 development for Thromboembolism prevention and treatment.

BAY 77-1931 is a direct thrombin inhibitor that blocks the active site of thrombin to prevent blood clot formation.

BAY 77-1931, also known as lanthanum carbonate, is a small molecule used in clinical trials to treat hyperphosphatemia. It has been studied in a phase III double-blind comparative study with calcium carbonate to determine its efficacy in patients with hyperphosphatemia.

Likelihood of approval

16.3% vs 15.3% industry baseline

If approved by FDA: likely 2031–2034

Steps remaining: Phase 3 → NDA/BLA submission

Confidence: Medium

Why this estimate

Baseline phase 2 → approval rate +15.3pp
Industry-wide phase 2 drugs reach approval ~15.3% of the time (BIO/Informa 2023 industry benchmark across all therapeutic areas).
Cardiovascular Phase 3 risk -2.0pp
Modern cardiovascular outcome trials are large + long; many fail to beat aggressive standard-of-care.
Big-pharma sponsor +3.0pp
Bayer is a top-20 pharma sponsor — historical approval rates run ~3pp above average due to scale, regulatory experience, and trial-design quality.

Predicted approval windows by jurisdiction (conditional on FDA approval)

Regulator	Country	Likely year	Lag vs FDA
FDA	US	2031–2034	—
EMA	EU	2032–2035	+0.7 yr
MHRA	GB	2032–2035	+0.7 yr
Health Canada	CA	2032–2036	+0.9 yr
TGA	AU	2032–2036	+1.2 yr
PMDA	JP	2032–2036	+1.5 yr
NMPA	CN	2033–2037	+2.3 yr
MFDS	KR	2032–2036	+1.4 yr
CDSCO	IN	2032–2037	+1.8 yr
ANVISA	BR	2033–2037	+2.3 yr

Hover any row for the lag rationale. Lag estimates are reduced when the drug has FDA Breakthrough or EMA PRIME designation (sponsors file globally in parallel).

Estimate based on the BIO/Informa industry phase transition rates plus per-drug modifiers for therapeutic area, sponsor type, FDA designations, mechanism, and trial design. Per-jurisdiction lags from Tufts CSDD international approval studies. Not investment, clinical or regulatory advice. Methodology: /methodology#likelihood.

At a glance

Generic name	BAY 77-1931
Sponsor	Bayer
Drug class	Direct thrombin inhibitor
Target	Thrombin (Factor IIa)
Modality	Small molecule
Therapeutic area	Cardiovascular
Phase	Phase 2

Mechanism of action

As a small-molecule direct thrombin inhibitor, BAY 77-1931 binds directly to the catalytic site of thrombin, preventing the conversion of fibrinogen to fibrin and thereby inhibiting coagulation cascade amplification. This mechanism allows for more predictable anticoagulation compared to indirect inhibitors like heparin, which require antithrombin as a cofactor.

Approved indications

Thromboembolism prevention and treatment

Common side effects

Bleeding
Gastrointestinal disturbances

Key clinical trials

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Source	Used for
ClinicalTrials.gov	Trial enrolment, design, endpoints, results

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

BAY 77-1931 CI brief — competitive landscape report
BAY 77-1931 updates RSS · CI watch RSS
Bayer portfolio CI

Frequently asked questions about BAY 77-1931

What is BAY 77-1931?

BAY 77-1931 is a Direct thrombin inhibitor drug developed by Bayer, indicated for Thromboembolism prevention and treatment.

How does BAY 77-1931 work?

BAY 77-1931 is a direct thrombin inhibitor that blocks the active site of thrombin to prevent blood clot formation.

What is BAY 77-1931 used for?

BAY 77-1931 is indicated for Thromboembolism prevention and treatment.

Who makes BAY 77-1931?

BAY 77-1931 is developed by Bayer (see full Bayer pipeline at /company/bayer).

What drug class is BAY 77-1931 in?

BAY 77-1931 belongs to the Direct thrombin inhibitor class. See all Direct thrombin inhibitor drugs at /class/direct-thrombin-inhibitor.

What development phase is BAY 77-1931 in?

BAY 77-1931 is in Phase 2.

What are the side effects of BAY 77-1931?

Common side effects of BAY 77-1931 include Bleeding, Gastrointestinal disturbances.

What does BAY 77-1931 target?

BAY 77-1931 targets Thrombin (Factor IIa) and is a Direct thrombin inhibitor.

Drug class: All Direct thrombin inhibitor drugs
Target: All drugs targeting Thrombin (Factor IIa)
Manufacturer: Bayer — full pipeline
Therapeutic area: All drugs in Cardiovascular
Indication: Drugs for Thromboembolism prevention and treatment

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing