Carbonic anhydrase Inhibitors
11 drugsAbout Carbonic anhydrase
Carbonic anhydrase catalyzes the interconversion of carbon dioxide and water to bicarbonate and protons. It is involved in various physiological processes, making it relevant to multiple therapeutic areas.
Human genetic studies provide strong validation for targeting CA2 (max score 0.87). Loss-of-function variants are associated with osteopetrosis and renal tubular acidosis, suggesting activation may be beneficial.
Carbonic anhydrase is targeted by 11 FDA-approved small molecule drugs, including TOPIRAMATE and EPRONTIA. These drugs are used in CNS disorders, metabolic conditions, and ophthalmology.
Carbonic anhydrase Genetic Evidence Strong
Genetic evidence strongly supports CA2 as a drug target (max score 0.87).
Strong genetic support increases confidence in target validation and clinical development.
💡 Why activation?
- • Loss-of-function variants increase disease risk (OR > 1) — restoring function may help
- • 100% directional consistency across 3 traits
- • Strong signal in urinary system disease, genetic, familial or congenital disease, musculoskeletal or connective tissue disease pathways
Cross-Disease Effects
Trade-off: LowDirection of Effect
100% alignedEvidence Across Diseases
5 totalGWAS and other genetic studies link CA2 to 5 diseases.
Loss-of-function causes disease; activation may help
Loss-of-function causes disease; activation may help
🔗 Colocalization Evidence 19 strong
max H4: 0.99eQTL/pQTL signals for CA2 colocalize with these GWAS traits, providing causal evidence that gene expression changes drive disease risk.
Understanding these scores
Association Score (0-1): Combines all evidence types (genetic, literature, drugs, animal models). Higher = more evidence linking target to disease. This is a ranking heuristic, not a confidence score.
L2G Score: Open Targets uses a machine learning model (Locus-to-Gene) to predict which gene is causal at each GWAS locus. L2G=0.5 means ~50% probability of being the causal gene. Only associations with L2G > 0.05 are included.
Odds Ratio (OR): From gene burden studies (UK Biobank, AstraZeneca PheWAS). Measures how loss-of-function variants affect disease risk. OR<1 = protective (inhibiting target may help), OR>1 = risk (losing function causes disease).
Beta (β): Effect size for continuous traits. β<0 = protective, β>0 = risk.
Clinical Translation (~1.8x): Based on Nelson et al. 2015: drug targets with genetic evidence have ~2x higher success rates in clinical trials. We estimate: Strong support (score ≥0.7) → ~1.8x, Moderate (0.3-0.7) → ~1.3x, Weak → baseline.
Colocalization (H4): Tests whether a GWAS signal and an eQTL/pQTL signal share the same causal variant. H4 is the posterior probability that both traits are associated AND share a causal variant. H4 > 0.8 = strong evidence that gene expression/protein levels drive disease risk. This links genetic variation → gene expression → disease, supporting the target-disease connection.
Top Carbonic anhydrase Drugs
Ten companies have approved drugs targeting carbonic anhydrase.
The presence of multiple players indicates a competitive market with moderate entry barriers.
| Drug | Company | Approved | Indications |
|---|---|---|---|
| QUDEXY XR | UPSHER SMITH LABS | 2014 | 5 |
| EPRONTIA | AZURITY | 2021 | 5 |
| TROKENDI XR | SUPERNUS PHARMS | 2013 | 5 |
| TOPIRAMATE | Teva | 2003 | 4 |
| ORMALVI | TORRENT | 2022 | 2 |
| DICHLORPHENAMIDE | RISING | 2025 | 2 |
| SIMBRINZA | Novartis | 2013 | 2 |
| ZONISADE | AZURITY | 2022 | 1 |
Carbonic anhydrase Drug Modality Landscape
Modalities
Routes of Administration
Carbonic anhydrase is amenable to small molecule drugs, with oral options available for convenient dosing.
Exploring alternative modalities like biologics could provide a competitive advantage.
Carbonic anhydrase Clinical Trials 234 trials
Phase 1-4 trials started in 2008 or later that test an FDA-approved drug acting on Carbonic anhydrase. Source: ClinicalTrials.gov. How we count
Completion by Phase
| Phase | Total | Completed | Stopped | Active | Completion |
|---|---|---|---|---|---|
| Phase 1 | 26 | 22 | 3 | 1 | 88% |
| Phase 2 | 58 | 34 | 16 | 8 | 68% |
| Phase 3 | 57 | 42 | 14 | 1 | 75% |
| Phase 4 | 93 | 69 | 9 | 13 | 88% |
Top Sponsors
By Modality
Top Conditions
Top Drugs
Carbonic anhydrase Drug Approval Timeline (1958 - 2025)
The first drug was approved in 1958, and the most recent in 2025.
The long approval history suggests sustained interest and potential for further innovation.
Pro Intelligence Preview
Deep insights for drug target analysis
Competitive Landscape
- • 10 companies competing
- • Market share by company
Full Drug Portfolio
- • All 11 approved drugs
- • Approval dates & indications
Genetic Validation
- • Full genetic evidence table
- • Effect sizes & directions
Approval Timeline
- • Full 11-drug timeline
- • First-of-modality markers
Clinical Trials Analysis
- • Sponsors: 120 (38 companies)
- • Completion rates by condition
Full summary • All drugs • Genetic evidence • Trials • Timeline
How We Count Trials
- Trials: phase 1-4 interventional trials on ClinicalTrials.gov that started in 2008 or later and test an FDA-approved drug acting on Carbonic anhydrase. A trial counts if an approved drug acting on Carbonic anhydrase is in any arm, including as a comparator, and a trial that tests two such drugs counts once. Trials that test only unapproved drugs are not counted. A trial listed as phase 1/2 counts as phase 1, and phase 2/3 as phase 2.
- Active: recruiting, not yet recruiting, enrolling by invitation, or active and no longer recruiting.
- Completion rate: of the trials that have ended, the share marked Completed rather than Terminated or Withdrawn. Completed means the trial ended as planned; it does not mean the drug worked. Suspended trials are not counted as ended.
- Stopped: terminated or withdrawn. Trials stop for many reasons, including slow enrolment and business decisions, not only safety or efficacy.
- Sponsors: the lead sponsor of each trial. Companies are the sponsors ClinicalTrials.gov classes as industry; the rest are universities, hospitals, cooperative groups, government bodies and individuals.