Which gut drugs might end up in a lawsuit? Are there really links with cancer and kidney disease? Should I stop taking them?
- Written by Nial Wheate, Professor and Director - Academic Excellence, Macquarie University
Common medicines used to treat conditions including heartburn, reflux, indigestion and stomach ulcers may be the subject of a class action lawsuit in Australia.
Lawyers are exploring whether long-term use of these over-the-counter and prescription drugs are linked to stomach cancer or kidney disease.
The potential class action follows the settlement of a related multi-million dollar lawsuit in the United States. Last year, international pharmaceutical company AstraZeneca settled for US$425 million (A$637 million) after patients made the case that two of its drugs caused significant and potentially life-threatening side effects.
Specifically, patients claimed the company’s drugs Nexium (esomeprazole) and Prilosec (omeprazole) increased the risk of kidney damage.
Which drugs are involved in Australia?
The class of drugs we’re talking about are “proton pump inhibitors” (sometimes called PPIs). In the case of the Australian potential class action, lawyers are investigating:
Depending on their strength and quantity, these medicines are available over-the-counter in pharmacies or by prescription.
They have been available in Australia for more than 20 years and are in the top ten medicines dispensed through the Pharmaceutical Benefits Scheme.
They are used to treat conditions exacerbated by stomach acid. These include heartburn, gastric reflux and indigestion. They work by blocking the protein responsible for pumping acid into the stomach.
These drugs are also prescribed with antibiotics to treat the bacterium Helicobacter pylori, which causes stomach ulcers and stomach cancer.
What do we know about the risks?
Appropriate use of proton pump inhibitors plays an important role in treating several serious digestive problems. Like all medicines, there are risks associated with their use depending on how much and how long they are used.
When proton pump inhibitors are used appropriately for the short-term treatment of stomach problems, they are generally well tolerated, safe and effective.
Their risks are mostly associated with long-term use (using them for more than a year) due to the negative effects from having reduced levels of stomach acid. In elderly people, these include an increased risk of gut and respiratory tract infections, nutrient deficiencies and fractures. Long-term use of these drugs in elderly people has also been associated with an increased risk of dementia.
In children, there is an increased risk of serious infection associated with using these drugs, regardless of how long they are used.
How about the cancer and kidney risk?
Currently, the Australian consumer medicine information sheets that come with the medicines, like this one for esomeprazole, do not list stomach cancer or kidney injury as a risk associated with using proton pump inhibitors.
So what does the evidence say about the risk?
Over the past few years, there have been large studies based on observing people in the general population who have used proton pump inhibitors. These studies have found people who take them are almost two times more likely to develop stomach cancer and 1.7 times more likely to develop chronic kidney disease when compared with people who are not taking them.
In particular, these studies report that users of the drugs lansoprazole and pantoprazole have about a three to four times higher risk than non-users of developing chronic kidney disease.
While these observational studies show a link between using the drugs and these outcomes, we cannot say from this evidence that one causes the other.
Researchers have not yet shown these drugs cause kidney disease.
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What can I do if I’m worried?
Several digestive conditions, especially reflux and heartburn, may benefit from simple dietary and lifestyle changes. But the overall evidence for these is not strong and how well they work varies between individuals.
But it may help to avoid large meals within two to three hours before bed, and reduce your intake of fatty food, alcohol and coffee. Eating slowly and getting your weight down if you are overweight may also help your symptoms.
There are also medications other than proton pump inhibitors that can be used for heartburn, reflux and stomach ulcers.
These include over-the-counter antacids (such as Gaviscon and Mylanta), which work by neutralising the acidic environment of the stomach.
Alternatives for prescription drugs include nizatidine and famotidine. These work by blocking histamine receptors in the stomach, which decreases stomach acid production.
If you are concerned about your use of proton pump inhibitors it is important to speak with your doctor or pharmacist before you stop using them. That’s because when you have been using them for a while, stopping them may result in increased or “rebound” acid production.
Authors: Nial Wheate, Professor and Director - Academic Excellence, Macquarie University
