H1 receptor Inhibitors
16 drugsAbout H1 receptor
The histamine H1 receptor (HRH1) is a G protein-coupled receptor that mediates histamine's effects, influencing inflammation, itching, and smooth muscle contraction. Its activation triggers downstream signaling cascades involved in allergic reactions and neurotransmission.
Human genetics provide moderate support for HRH1 as a therapeutic target, with variants linked to cholelithiasis (score 0.46) and male infertility (score 0.45). Colocalization analysis reveals 20 strong eQTL/pQTL signals, suggesting a role in gene regulation.
HRH1 is targeted by 13 FDA-approved small molecule drugs, including DOXEPIN HYDROCHLORIDE (first approved in 1972) and TONMYA (approved in 2025). Top drugs include KARBINAL ER and HYDROCODONE POLISTIREX AND CHLORPHENIRAMINE POLISTIREX.
H1 receptor Genetic Evidence Moderate
Genetic evidence offers moderate support for HRH1's role in diseases like cholelithiasis and male infertility.
Further research into the causal genes within the 20 strong eQTL/pQTL signals could reveal novel therapeutic opportunities.
Evidence Across Diseases
8 totalGWAS and other genetic studies link HRH1 to 8 diseases.
🔗 Colocalization Evidence 20 strong
max H4: 0.98eQTL/pQTL signals for HRH1 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 H1 receptor Drugs
Thirteen companies have approved drugs targeting HRH1, including BIONPHARMA and Teva.
The presence of multiple players suggests a competitive market, requiring differentiated strategies for new entrants.
| Drug | Company | Approved | Indications |
|---|---|---|---|
| CARBINOXAMINE MALEATE | STRIDES PHARMA INTL | 2003 | 7 |
| CLARINEX-D 12 HOUR | Merck | 2006 | 2 |
| DOXEPIN HYDROCHLORIDE | ZYDUS LIFESCIENCES | 1972 | 1 |
| BEPOTASTINE BESILATE | ALEMBIC | 2019 | 1 |
| AZELASTINE HYDROCHLORIDE AND FLUTICASONE PROPIONATE | PADAGIS ISRAEL | 2017 | 1 |
| DYMISTA | Viatris | 2012 | 1 |
| TONMYA | TONIX | 2025 | 1 |
| SILENOR | CURRAX | 2010 | 1 |
| BEPREVE | BAUSCH AND LOMB INC | 2009 | 1 |
| ZERVIATE | HARROW EYE | 2017 | 1 |
| RYALTRIS | GLENMARK SPECLT | 2022 | 1 |
| QUZYTTIR | ESTEVE | 2019 | 1 |
| DESLORATADINE AND PSEUDOEPHEDRINE SULFATE 24 HOUR | Dr. Reddy's | 2011 | - |
H1 receptor Drug Modality Landscape
Modalities
Routes of Administration
H1 receptor is amenable to small molecule drugs, with oral options available for convenient dosing.
Exploring alternative modalities like antibodies or biologics could provide a competitive advantage in targeting HRH1.
H1 receptor Clinical Trials 328 trials
Phase 1-4 trials started in 2008 or later that test an FDA-approved drug acting on H1 receptor. Source: ClinicalTrials.gov. How we count
Completion by Phase
| Phase | Total | Completed | Stopped | Active | Completion |
|---|---|---|---|---|---|
| Phase 1 | 49 | 44 | 3 | 2 | 94% |
| Phase 2 | 81 | 54 | 13 | 14 | 81% |
| Phase 3 | 115 | 89 | 16 | 9 | 85% |
| Phase 4 | 83 | 68 | 7 | 8 | 91% |
Top Sponsors
By Modality
Top Conditions
Top Drugs
H1 receptor Drug Approval Timeline (1972 - 2025)
Seasonal Allergic Rhinitis
Drug approvals for HRH1 span 54 years, from 1972 to 2025, indicating sustained interest.
The recent approval of TONMYA suggests continued innovation, but market saturation may necessitate novel approaches.
Pro Intelligence Preview
Deep insights for drug target analysis
Competitive Landscape
- • 16 companies competing
- • Market share by company
Full Drug Portfolio
- • All 16 approved drugs
- • Approval dates & indications
Genetic Validation
- • Full genetic evidence table
- • Effect sizes & directions
Approval Timeline
- • Full 16-drug timeline
- • First-of-modality markers
Clinical Trials Analysis
- • Sponsors: 174 (85 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 H1 receptor. A trial counts if an approved drug acting on H1 receptor 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.