If you have taken a proton pump inhibitor for eight weeks and your heartburn is still there, you are not an unusual case. Roughly one in five people with erosive esophagitis does not heal on a standard PPI course, and the gap is widest in those with the most damage.
A newer drug class, the potassium-competitive acid blocker or P-CAB, was built for exactly that gap.
Through 2025 and 2026 it moved from “promising alternative” to a treatment with head-to-head trial data, and in one 2026 trial it did something no P-CAB had done before against a PPI.[3]
What a potassium-competitive acid blocker actually does
Stomach acid is pumped out by an enzyme in the stomach lining often called the acid pump. A PPI has to be activated by acid before it can disable that pump, and it only binds pumps that are already switched on.
That is why PPIs are taken before a meal and why they take several days to reach full effect.
A P-CAB blocks the same pump by competing for its potassium binding site instead. It needs no acid activation, works on resting pumps as well as active ones, and reaches a steady effect from the first or second dose. It also has a longer half-life, which matters most overnight.[8]
Two practical consequences follow. Meal timing stops being critical, and the drug is far less affected by the genetic variation in the liver enzyme CYP2C19 that makes some people poor responders to certain PPIs.
In East Asian populations that variation is common enough to be clinically visible.[8]
The vonoprazan trials: equal overall, better where it is hardest
Vonoprazan is the most studied P-CAB outside Japan. In a phase 3 randomized trial of 1,024 patients with erosive esophagitis, it was noninferior to lansoprazole for both initial healing and maintained healing, with initial healing in 92.9 percent of patients versus 84.6 percent.[1]
The more interesting result was the subgroup analysis. In the same programme, run across the United States and Europe, vonoprazan was superior to lansoprazole for both healing and maintenance specifically in severe disease, meaning LA grade C or D.[2]
Where the damage was mild, the two drugs were interchangeable.
That pattern has held up across reviews and is now the standard way clinicians describe the class: no meaningful advantage in easy cases, a real advantage in difficult ones.
It is an unusually clean signal, because the harder-to-treat group is exactly where a stronger acid block should show itself.
Tegoprazan: the first clear superiority result
Tegoprazan is a P-CAB developed in Korea. Its earlier Korean trial showed the expected pattern: at 50 or 100 mg once daily it was noninferior to esomeprazole 40 mg, healing 90.3 percent versus 88.5 percent at week 4 and 99.1 percent versus 99.1 percent at week 8.[5]
The 2026 TRIUMpH trial changed the picture. Against lansoprazole, tegoprazan met complete healing at week 8 in 84.6 percent of patients versus 78.0 percent, clearing both the noninferiority and the superiority thresholds.[3]
More than three quarters of patients were healed by week 2.
Maintenance told a similar story. At week 24, sustained complete healing across all LA grades was 69.4 percent on tegoprazan 100 mg and 61.4 percent on 50 mg, against 50.6 percent on lansoprazole.[3]
A third Korean P-CAB, fexuprazan, has been compared with esomeprazole in a 2025 meta-analysis of randomized trials.[6]
What the guidelines actually say right now
Trial results and guideline text are not the same thing.
The American Gastroenterological Association clinical practice update, published in 2024, is deliberately conservative: clinicians should generally not use P-CABs as first-line therapy in milder erosive esophagitis, LA grade A or B.[2]
Where the update does open the door is for patients with documented acid-related reflux who have failed twice-daily PPI therapy.
Reviews add three more situations where a P-CAB is reasonable: severe esophagitis, clarithromycin-resistant Helicobacter pylori infection, and PPI intolerance.[4]
So the honest summary in September 2026 is that PPIs remain the default first step, and a P-CAB is the considered second step or the first step in a clearly severe case. The 2026 superiority data may move that line, but guideline committees move slowly and deliberately.
What we still do not know
Three gaps matter. First, long-term safety data for P-CABs are far younger than the decades of PPI experience. They suppress acid more completely, which raises the level of the hormone gastrin more, and the long-run meaning of that is not settled.
Second, almost all the trials measure healing on endoscopy rather than how patients feel a year later, and symptom relief and visible healing do not always move together.
Third, most of the tegoprazan and fexuprazan data come from East Asian populations, where CYP2C19 variation differs from other groups.
Cost is the fourth, less scientific gap. In most markets a P-CAB is meaningfully more expensive than a generic PPI, which is one reason “not first-line for mild disease” is a defensible position rather than an overcautious one.
What this means if you are the patient
Nothing here is a reason to stop a PPI that is working.
The useful takeaway is narrower: if you have completed a full eight-week course, ideally twice daily, and either your symptoms or a follow-up endoscopy say you have not healed, that is a specific, recognised situation with a specific option attached to it.
Bring three things to that conversation — how long you have taken the drug, at what dose, and whether you take it before eating.
The last one matters more than most people realise, because a PPI taken after a meal loses a large share of its effect and can look like a treatment failure when it is a timing problem.
| Aspect | Finding |
|---|---|
| Time to full effect | PPI needs several days of dosing; a P-CAB reaches steady acid suppression from the first or second dose |
| Meal timing | PPI must be taken before eating to work properly; a P-CAB is largely independent of meals |
| Genetic variation | PPI effect varies with CYP2C19 status; P-CAB effect is much less affected |
| Mild esophagitis (LA A/B) | No meaningful difference; guidelines advise against P-CAB as first-line here |
| Severe esophagitis (LA C/D) | Vonoprazan superior to lansoprazole for both healing and maintenance |
| Best 2026 head-to-head | Tegoprazan 84.6% vs lansoprazole 78.0% complete healing at week 8, superiority met |
| Six-month maintenance | Tegoprazan 100 mg 69.4% and 50 mg 61.4% vs lansoprazole 50.6% at week 24 |
| Main open question | Long-term safety of deeper acid suppression, and cost versus generic PPIs |
References
- Vonoprazan versus lansoprazole for healing and maintenance of healing of erosive esophagitis, phase 3 randomized trial in 1,024 patients (PHALCON-EE programme), reported in Gastroenterology
- AGA Clinical Practice Update on Integrating Potassium-Competitive Acid Blockers Into Clinical Practice: Expert Review, Gastroenterology, 2024
- Tegoprazan TRIUMpH phase 3 trial results in erosive esophagitis, reported by Medscape Medical News, 2026
- Will Vonoprazan Be the New First-Line Erosive Esophagitis Treatment?, Gastroenterology Advisor
- Bandyopadhyay S, et al. Tegoprazan in Gastroesophageal Reflux Disease and Related Acid-Mediated Conditions: A Systematic Review and Meta-Analysis, JGH Open, 2026
- Fexuprazan and Esomeprazole in Patients with Disorders Associated with Acid Reflux: A Comprehensive Review and Meta-Analysis of Randomized Controlled Trials, 2025
- Lapidot Alon N, Wong R, Navarro-Rodriguez T, Jimenez-Castillo RA, Fass R. Future Opportunities for Potassium Competitive Acid Blocker in Gastroesophageal Reflux Disease and Beyond, Foregut, 2026
- Potassium-competitive acid blockers: Clinical pearls and practical insights, Cleveland Clinic Journal of Medicine, 2026;93(6):341
