Anyone who likes to eat and drink opulently knows the feeling: a sharp burning sensation that slowly rises up the throat, plus the urge to burp constantly. The cause of heartburn is acidic gastric juice, which gets back into the oesophagus. Often the symptoms are gone after a short time. However, for people who suffer from chronic heartburn, these symptoms become a real burden in everyday life. For some years now, stomach acid blockers with active ingredients such as pantoprazole or omeprazole have been helping them. Their principle is simple: So-called proton pump inhibitors (PPI) inhibit a certain enzyme in the stomach mucosa and thus reduce the production of the caustic fluid.
Ulcers or inflammation of the mucous membranes in the stomach, often caused by an excess of stomach acid, are also treated with the drugs. By reducing the acid, the affected mucous membrane can recover. Doctors have long been happy to prescribe the drugs prophylactically to accompany high-dose therapies with cortisone or painkillers, because many of these treatments make ulcers and stomach bleeding more likely. This is because drugs such as ibuprofen, aspirin and cortisone inhibit the production of the protective stomach mucus.
PPIs are now among the most frequently prescribed drugs in Germany. According to the Scientific Institute of the AOK, the total number of medical prescriptions has increased 14-fold over the last twenty years. In 2018, doctors prescribed around 3.6 billion daily doses, and actual consumption is even higher. Many of the drugs with low active ingredient doses have been available without a prescription in pharmacies since 2009 – and many patients are only too happy to use them. Almost five million packages went over the counter without a prescription last year – after all, this represents around 13 percent of total PPI sales. This is shown by data from the IMS PharmaScope, which was compiled by the market research company IQVIA at the request of ZEIT ONLINE.
This could not be without consequences. A regular and permanent intake of PPI is suspected to have a whole list of negative side effects: For example, the risk of dementia, heart attack or bone fractures (osteoporosis) is said to be significantly increased (JAMA Neurology: Gomm et al., 2016; Plos One: Shah et al., 2015; American Journal of Medicine: Yu et al., 2011). Long-term PPI use is also believed to increase susceptibility to infections, kidney disease and stomach cancer (American Journal of Gastroenterology: Kwok et al., 2012; Kidney International: Blank et al., 2014; Gut: Chung, Chan, Wong et al., 2018). Recently, the report that Austrian researchers had found a statistical correlation between the intake of acid blockers and a later allergy risk of the patients caused a sensation (Nature Communications: Jordakieva, Kundi, Untersmayr, et al., 2019). The highlight of the series was a study presented by researchers from the University of Saint Louis in 2017: Over an approximately six-year observation period, the mortality risk of PPI users was significantly increased compared to participants who did not take acid blockers (BMJ Open: Xie, Bowe, Li et al., 2017).
It is hardly surprising that the popular tablets are now also said to be associated with Covid-19. At least that is what the first studies suggest, which have recently been the subject of debate in the scientific community. For example, a preliminary publication from the USA, based on an online survey, comes to the conclusion that PPI users are more frequently infected with Sars-CoV-2. Depending on the PPI dose, the probability of a positive corona test was between twice and four times higher (American Journal of Gastroenterology: Almario, Chey, Spiegel, 2020, PDF).
In a study that has also not yet been reviewed, American researchers report that Covid-19 patients who had previously taken PPI regularly had a mortality risk that was more than twice as high as that of a control group. They were also more likely to require artificial respiration during treatment (MedRxiv: Preethi et al., 2020, PDF).
The presumed biological mechanisms underlying many of these dangers sound quite plausible. Take dementia, for example: the risk of disease could be increased by a permanent deficiency of vitamin B12, and PPIs in turn inhibit the release of a protein that is essential for vitamin B12 to pass from food into the blood.
A similar pattern of action is suspected behind the increased risk of bone fracture. Finally, gastric acid releases the mineral calcium from food, which is considered the most important bone building block. If this is no longer successful because of the acid blockers, the body eventually breaks down bones in order to maintain the calcium content in the blood.
With regard to the new coronavirus, the authors of the current papers refer to studies that show that infections with sars-CoV-2 may also be possible via the gastrointestinal tract (Gastroenterology: Xiao et al., 2020). The hypothesis: If the viruses find a less acidic environment there thanks to PPI, this favours their infectivity. This does not seem unlikely – after all, it has been shown with the predecessor Sars-Cov that low and thus acidic pH values can render the virus completely ineffective. Higher values, such as those caused by gastric acid blockers, did not, however, have anything against the intruders (Journal of Virological Methods: Darnell et al, 2004).
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