Michael Vaezi, MD, and David Peura, MD, on Acid Suppression in H pylori Treatment

Discover the importance of acid suppression in H. pylori treatment with hosts Dr Michael Vaezi, professor of medicine at Vanderbilt University Medical Center and Dr David Peura, professor emeritus at the University of Virginia School of Medicine.

Announcer:  This program is sponsored by Phathom Pharmaceuticals and is intended for physicians in the United States.

Dr. Michael Vaezi:  When faced with patients who have failed Helicobacter pylori eradications, we often focus on types of antibiotic use, but what about adequacy of acid suppression?

Hello, and welcome to fireside chats, a series on acid-related disorders in clinical practice. I'm your host, Dr. Michael Vaezi, a professor of medicine at Vanderbilt University Medical Center, and I'm joined today by my friend Dr. David Peura, professor emeritus at the University of Virginia School of Medicine.

Dr. David Peura:  Thank you for inviting me today. This is certainly a topic I feel passionate about.

Dr. Vaezi:  Perhaps, we can start by talking about the problem of declining Helicobacter pylori, or H. pylori, eradication rates with the standard regimen. A recent publication that examined the standard 14-day triple therapy regimen that included clarithromycin — this was from Rhode Island— showed eradication rates of only 79%.

This means about 1 in 5 patients failed these first-line therapies. What factors do you think are contributing to these rates of treatment failure?

Dr. Peura:  Well, there's probably not one simple answer, as bacteria have robust mechanisms to develop resistance, but we know overuse and misuse of antibiotics facilitate resistance. Part of misuse can be prescribing antibiotics such as clarithromycin with known resistance rates greater than 15% in some regions.

It's also important to consider patient antibiotic use history and to avoid antibiotics that have been previously taken to help prevent secondary H. pylori resistance that may have resulted from prior treatment.

Dr. Vaezi:  And beyond treatment choices, patient adherence can also pose a challenge that ultimately contributes to lower eradication rates, right?

Dr. Peura:  Right. Patient adherence to therapy can influence treatment success, and data on patient adherence for H. pylori treatment showed that those patients who complete more of their prescribed regimen have higher eradication rates.

Dr. Vaezi:  Now, what do you think contributes to the lower than ideal adherence?

Dr. Peura:  Some of it probably is likely to do with the complexity of the regimens which require a large number of pills taken 2 to 4 times a day for 7 to 14 days that may need to be timed according to meals. And for some patients, the side effects are just intolerable, and its poor adherence contributes to treatment failure.

Dr. Vaezi:  So far, we've focused on prescribing decisions and patients’ behaviors, but what I really brought you on to discuss today is the impact that pH or gastric acidity has on the probability of eradication treatment success.

Dr. Peura:  This is actually very exciting because we can increase the probability of eradication by optimizing acid suppression in the pH of the stomach environment during eradication treatment.

Dr. Vaezi:  I think too many of us have really forgotten about this critical aspect of acid suppression when we're dealing with eradication treatment, especially when it comes to H. pylori, which is a bit unique, right?

Dr. Peura:  Exactly. H. pylori replicates more rapidly at a neutral pH, ideally, between 6 and 7. At a lower acidic pH, its replication really slows down.

Dr. Vaezi:  Of course, that's a problem when you're using growth-dependent antibiotics like clarithromycin and amoxicillin, right?

Dr. Peura:  Exactly. The most commonly used antibiotics and eradication regimens require bacteria to be in a replicating stage. Otherwise, the nonreplicating bacteria remain and can recolonize as soon as you stop the antibiotics.

Dr. Vaezi:  That's really important, but additionally, I know that the stability of antibiotic is also impacted by pH. For example, one in vitro study that compared the degradation time of antibiotics that we commonly use to eradicate H. pylori like clarithromycin and amoxicillin—what they did, they studied the degradation at different pHs — pH 2 and pH 7.

What they found was that clarithromycin had a degradation half-life of 1 hour at acidic pH, pH 2. Whereas amoxicillin, it was 15.2 hours. When they raised the pH to pH 7, both antibiotics had increased half-lives over 68 hours.

Dr. Peura:  Clearly, there is some variability, but overall a pH above 6 over 24 hours is likely ideal when treating H. pylori, although maintaining that can be a challenge.

Dr. Vaezi:  That's definitely a challenge especially since twice-daily PPI use such as lansoprazole, omeprazole, and pantoprazole — and these are acid-suppressive agents we commonly use when we tried to do eradication of H. pylori — have shown that the mean 24-hour hold time of pH over 6 ranges from 23% to 55%.

Dr. Peura:  That may not be sufficient because sustaining that optimal pH level is really important, and we also know that absorption of these drugs may be influenced by meals. These factors are especially important to consider when treating patients with a multiantibiotic regimen as it requires the pH to be optimized for all antibiotics to work efficiently.

Dr. Vaezi:  That's really an important point, especially since testing for resistance prior to treatment is not routinely done in clinical practice. If you're giving your patients multiple antibiotics, you certainly want to give each of them the best chance to work.

Dr. Peura:  It's almost like we're doing our best to cover our bases using triple or quadruple therapies, but then we may not succeed because of insufficient acid suppression that's necessary for all those antibiotics to work most effectively. This leaves it open for additional antibiotic resistance to develop.

Dr. Vaezi:  Absolutely. That's definitely something all of us should consider when making treatment choices. So to recap, it's important that we pay attention to our patient's antibiotic history and avoid prescribing antibiotics such as clarithromycin if you're in a region where the resistance rate is greater than 15%.

Furthermore, it's important to consider the role of intragastric pH on treatment success. This may include considering our acid-oppressive options including the impact of higher doses of PPIs or more frequent dosing on treatment success. Dr. Peura, thank you so much for joining us today.

Dr. Peura:  Michael, it was a pleasure, and thanks for having me.

Dr. Vaezi:  For everyone listening, I hope this podcast has provided you with an overview of the importance of sufficient acid suppression for eradicating H. pylori. Thank you for joining us today on fireside chats and be on the lookout for the next podcast in the series, where we will discuss potential complications resulting from unresolved H. pylori infection.

Announcer:  The references for the information discussed today are available in the transcript which can be accessed on the site where you've listened to the podcast.