Protein / target

Carbonic anhydrase 2

CA2P00918Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
11
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

Carbonate dehydratase activity

Primary system

Musculoskeletal system

Strongest disease association

Osteopetrosis with renal tubular acidosis

Genetic evidence · score 0.87

Therapeutic maturity

Clinically validated target

11 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Approved Drug

Clinical development

11 approved

30 linked trials

Derived from structured UniProt, Open Targets and literature data on this page.

Protein profile

UniProt 2026_02

Canonical identity and biological annotation from UniProt.

Function

Catalyzes the reversible hydration of carbon dioxide (PubMed:11327835, PubMed:11802772, PubMed:11831900, PubMed:12056894, PubMed:12171926, PubMed:1336460, PubMed:14736236, PubMed:15300855, PubMed:15453828, PubMed:15667203, PubMed:15865431, PubMed:16106378, PubMed:16214338, PubMed:16290146, PubMed:16686544, PubMed:16759856, PubMed:16807956, PubMed:17127057, PubMed:17251017, PubMed:17314045, PubMed:17330962, PubMed:17346964, PubMed:17540563, PubMed:17588751, PubMed:17705204, PubMed:18024029, PubMed:18162396, PubMed:18266323, PubMed:18374572, PubMed:18481843, PubMed:18618712, PubMed:18640037, PubMed:18942852, PubMed:1909891, PubMed:1910042, PubMed:19170619, PubMed:19186056, PubMed:19206230, PubMed:19520834, PubMed:19778001, PubMed:7761440, PubMed:7901850, PubMed:8218160, PubMed:8262987, PubMed:8399159, PubMed:8451242, PubMed:8485129, PubMed:8639494, PubMed:9265618, PubMed:9398308). Can also hydrate cyanamide to urea (PubMed:10550681, PubMed:11015219). Stimulates the chloride-bicarbonate exchange activity of SLC26A6 (PubMed:15990874). Essential for bone resorption and osteoclast differentiation (PubMed:15300855). Involved in the regulation of fluid secretion into the anterior chamber of the eye. Contributes to intracellular pH regulation in the duodenal upper villous epithelium during proton-coupled peptide absorption

Subcellular location

CytoplasmCell membrane
Domains and Gene Ontology detail (15)

Domains & features

Alpha-carbonic anhydrase

Gene Ontology

  • Capical part of cell
  • Ccytoplasm
  • Ccytosol
  • Cextracellular exosome
  • Cplasma membrane
  • Farylesterase activity
  • Fcarbonate dehydratase activity
  • Fcyanamide hydratase activity
  • Fzinc ion binding
  • Pangiotensin-activated signaling pathway
  • Pcarbon dioxide transport
  • Ppositive regulation of dipeptide transmembrane transport

260 aa · 29 kDa

Biological roles

Reactome v97

What this protein does, drawn together from its UniProt function, Gene Ontology terms and Reactome pathways.

View underlying pathways (4)

Concepts derived from UniProt GO Reactome — each badge above shows which sources supported that role.

Interaction neighbourhood

STRING v12.0

Proteins with the strongest functional or physical association. Node size and line weight reflect STRING confidence; hover or select a partner to inspect one association.

SLC9A1SLC4A1SLC4A4TCIRG1ATP6V1…CA1CBSLCBSCLCN7CYP24A1CA2

10 strongest partners — larger node and heavier line mean higher confidence

Functional and physical associations from STRING v12.0. Only associations with this protein are drawn — partner-to-partner links are not part of this evidence.

Drugs targeting this protein

1

Whether each drug engages this protein directly or through a complex, and how many other targets are recorded for it. Direct binders with few recorded targets are listed first.

Acetazolamide
ApprovedInhibitor

Carbonic anhydrase II inhibitor

Appears in clinical studies involving Seizure, glaucoma, edema, angle-closure glaucoma

Direct interaction with this protein · 1 of 4 recorded protein targets

ChEMBL mechanism, action type and target identity. Open Targets clinical status and indications.

Translational evidence

Open Targets 26

Why this target matters therapeutically — disease associations, drugs in development, tractability and safety, from Open Targets.

Strongest genetic associations

Human genetic evidence — the most direct causal link between this target and a disease.

Osteopetrosis with renal tubular acidosis0.87

Genetic · overall 0.79

autosomal recessive osteopetrosis 30.84

Genetic literature · overall 0.78

Highest-confidence therapeutic associations

Diseases where a drug acting on this target has already reached clinical development.

epilepsy0.99

Clinical · overall 0.61

ocular hypertension0.99

Clinical · overall 0.61

open-angle glaucoma0.99

Clinical · overall 0.60

glaucoma0.99

Clinical · overall 0.61

Seizure0.98

Clinical · overall 0.59

Highest overall evidence

Remaining associations by Open Targets' aggregated evidence score.

angle-closure glaucoma0.59

Clinical

altitude sickness0.59

Clinical

edema0.59

Clinical

Show all associations
Osteopetrosis with renal tubular acidosis0.79
autosomal recessive osteopetrosis 30.78
glaucoma0.61
epilepsy0.61
ocular hypertension0.61
open-angle glaucoma0.60
Seizure0.59
angle-closure glaucoma0.59
altitude sickness0.59
edema0.59

Open Targets ranks 918 associations for this target and we store the top 10 by aggregated score. The long tail is largely literature co-mention and RNA-expression evidence, not evidence that this target drives those diseases.

Known drugs · 11 total

ETHOXZOLAMIDEApproval

duodenal ulcer

DICHLORPHENAMIDEApproval

glaucoma · paramyotonia congenita of Von Eulenburg · hyperkalemic periodic paralysis

TOPIRAMATEApproval

epilepsy · migraine disorder · Lennox-Gastaut syndrome

SULTHIAMEApproval

epilepsy · obstructive sleep apnea syndrome · childhood-onset epilepsy syndrome

DORZOLAMIDEApproval

open-angle glaucoma · glaucoma · ocular hypertension

ACETAZOLAMIDE SODIUMApproval

Seizure · angle-closure glaucoma · edema

DORZOLAMIDE HYDROCHLORIDEApproval

open-angle glaucoma · ocular hypertension · glaucoma

METHAZOLAMIDEApproval

glaucoma · open-angle glaucoma · type 2 diabetes mellitus

BRINZOLAMIDEApproval

glaucoma · ocular hypertension · open-angle glaucoma

POLMACOXIBApproval

rheumatic disorder · Arthritis · osteoarthritis

Tractability

SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · High-Quality PocketSM · Druggable FamilyAB · UniProt loc high confAB · GO CC high confPR · Database UbiquitinationPR · Half-life DataPR · Small Molecule Binder

Clinical trials

30

Trials of drugs that target this protein — reached indirectly through those drugs, so a trial listed here studies the drug, not the protein.

Show remaining trials (24)

RECRUITING · via Acetazolamide · NCT02703220

COMPLETED · via Acetazolamide · NCT05589792

COMPLETED · via Acetazolamide · NCT00223691

COMPLETED · via Acetazolamide · NCT00714740

TERMINATED · via Acetazolamide · NCT02466074

ClinicalTrials.gov via the drug-target graph.

Forefront confidence

Synthesis

Our own weighting of the evidence behind each disease association. Human genetics and clinical evidence count for most; literature co-mention counts for little, because two entities sharing an abstract is not evidence that one drives the other.

Osteopetrosis with renal tubular acidosisWell supported
0.89
agreement 0.771.00
Genetic87%Animal model13%Genetic literaturedup

Open Targets aggregate 0.79 · 2 independent evidence families · 1 not counted as duplicate

autosomal recessive osteopetrosis 3Well supported
0.78
agreement 0.650.92
Genetic100%Literature0%Genetic literaturedup

Open Targets aggregate 0.78 · 2 independent evidence families · 1 not counted as duplicate

glaucomaWell supported
0.76
agreement 0.600.91
Clinical92%Literature8%

Open Targets aggregate 0.61 · 2 independent evidence families

epilepsyWell supported
0.75
agreement 0.590.91
Clinical98%Literature2%

Open Targets aggregate 0.61 · 2 independent evidence families

ocular hypertensionModerately supported
0.75
agreement 0.590.90
Clinical98%Literature2%

Open Targets aggregate 0.61 · 2 independent evidence families

The evidence agreement range shows how closely the independent evidence families agree — it is not a statistical confidence interval, and nothing here is fitted to outcome data. Derived from Open Targets evidence types under Forefront weighting; the underlying per-type scores are shown above so the calculation can be checked.

What's happening now

15

Recent activity around this target, drawn from one canonical event stream. Every item is reached through a drug that targets this protein, so each event is news about that drug rather than about the protein directly.

  1. Label change2026-07-14

    Label change: ACETAZOLAMIDE (ANDA040904)

    fda · regulatory · fda · via Acetazolamide

  2. Label change2026-07-01

    Label change: ACETAZOLAMIDE (ANDA040089)

    fda · regulatory · fda · via Acetazolamide

  3. Label change2026-06-05

    Label change: ACETAZOLAMIDE (ANDA202693)

    fda · regulatory · fda · via Acetazolamide

  4. Label change2024-07-26

    Label change: ACETAZOLAMIDE (ANDA202693)

    fda · regulatory · fda · via Acetazolamide

  5. Label change2024-07-26

    Label change: ACETAZOLAMIDE (ANDA202693)

    fda · regulatory · fda · via Acetazolamide

  6. Label change2024-01-25

    Label change: ACETAZOLAMIDE (ANDA040089)

    fda · regulatory · fda · via Acetazolamide

  7. New publication2023-07-18
    Treatment with GLP-1 receptor agonists is associated with significant weight loss and favorable headache outcomes in idiopathic intracranial hypertension.

    The journal of headache and pain · 2023 · 56 citations · Europe PMC · via Acetazolamide

  8. Label change2023-01-23

    Label change: ACETAZOLAMIDE (ANDA040904)

    fda · regulatory · fda · via Acetazolamide

  9. New publication2022-08-27
    Acetazolamide in Acute Decompensated Heart Failure with Volume Overload.

    The New England journal of medicine · 2022 · 374 citations · Europe PMC · via Acetazolamide

  10. Regulatory approval2014-12-19

    Approval: ACETAZOLAMIDE (ANDA202693)

    fda · regulatory · fda · via Acetazolamide

  11. New publication2014-04-01
    Effect of acetazolamide on visual function in patients with idiopathic intracranial hypertension and mild visual loss: the idiopathic intracranial hypertension treatment trial.

    JAMA · 2014 · 363 citations · Europe PMC · via Acetazolamide

  12. Regulatory approval2008-12-10

    Approval: ACETAZOLAMIDE (ANDA040904)

    fda · regulatory · fda · via Acetazolamide

Objective event titles are shown unmodified; the event kind and significance line are derived from structured fields. Forefront AttentionEvent stream aggregating Europe PMC Regulatory filings ClinicalTrials.gov.