Lansoprazole
Lansoprazole is a gastric proton pump inhibitor, according to its UK product information. It is used in adults to heal and relieve the symptoms of active duodenal ulcer, and, combined with amoxicillin and clarithromycin as triple therapy, to eradicate the Helicobacter pylori infection behind duodenal ulcer disease, as set out in its US prescribing information. In common with other anti-ulcer therapies, a gastric ulcer should be confirmed as non-malignant before treatment, because lansoprazole can mask symptoms and delay diagnosis.
Key points
- Lansoprazole clears from the blood in under two hours, but its acid-suppressing effect on the stomach lasts more than 24 hours.
- It is broken down by the liver’s cytochrome P450 system, specifically the CYP3A and CYP2C19 enzymes.
- During 14 days of triple therapy with amoxicillin and clarithromycin, the most frequently reported reactions were diarrhoea (7%), headache (6%) and taste disturbance (5%).
- Its capsules contain acid-resistant granules, because lansoprazole itself is broken down by stomach acid, so absorption begins only once the granules have passed through the stomach.
How it works
Lansoprazole is a gastric proton pump inhibitor. It inhibits the final stage of gastric acid formation by inhibiting the activity of H+/K+ ATPase of the parietal cells in the stomach. It becomes concentrated in these cells and activated by their acidic environment, where it reacts with the enzyme to switch off acid production. This inhibition is reversible and reduces both baseline and stimulated acid secretion in the stomach. Lansoprazole does not exhibit anticholinergic or histamine type-2 antagonist activity.
Safety specific to lansoprazole
Symptom improvement while taking lansoprazole does not rule out a more serious underlying cause: in adults, a symptomatic response to therapy does not preclude the presence of gastric malignancy, so persistent or new stomach symptoms may still need investigation.
Several published observational studies suggest that taking a proton pump inhibitor such as lansoprazole may be associated with an increased risk of fractures of the hip, wrist or spine linked to osteoporosis.
Long-term use can also affect nutrient and mineral levels. Daily treatment with any acid-suppressing medicine for longer than three years may lead to malabsorption of vitamin B12. Low magnesium levels, with or without symptoms, have rarely been reported in people treated with proton pump inhibitors for at least three months, most often after a year of treatment.
When to seek urgent care
Tell a doctor promptly about new or worsening diarrhoea while taking lansoprazole, especially if you are in hospital: published observational studies suggest that PPI therapy like lansoprazole may be associated with an increased risk of Clostridium difficile-associated diarrhoea.