Lansoprazole is a proton pump inhibitor (PPI) that suppresses gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. The 15mg strength is commonly used for maintenance therapy and in specific conditions like non-erosive reflux disease (NERD). It is a substituted benzimidazole prodrug that is activated in the acidic environment of the parietal cell canaliculus.
Adult: For maintenance of healed erosive esophagitis: 15mg once daily. For NERD: 15mg once daily for up to 8 weeks. For H. pylori eradication: 30mg twice daily (as part of combination therapy) for 10-14 days.
Note: Take on an empty stomach, at least 30-60 minutes before a meal (preferably before breakfast). Swallow the capsule whole; do not crush, chew, or split. For patients with difficulty swallowing, the capsule can be opened and the granules sprinkled on 1 tablespoon of applesauce, yogurt, or acidic fruit juice (e.g., apple, orange) and swallowed immediately without chewing. The orally disintegrating tablet (ODT) should be placed on the tongue, allowed to disintegrate, and swallowed with or without water. Do not split or chew the ODT.
Lansoprazole is a prodrug that accumulates in the acidic compartment of the parietal cell. It is activated to a sulfenamide derivative which forms covalent disulfide bonds with cysteine residues (Cys813 and Cys321) on the alpha subunit of the H+/K+ ATPase (proton pump). This binding irreversibly inhibits the enzyme's function, blocking the final step of gastric acid secretion.
Pregnancy: Pregnancy Category B (US FDA). Animal studies have shown no risk, but adequate and well-controlled studies in pregnant women are lacking. Use during pregnancy only if clearly needed. Indian guidelines suggest using only when potential benefit justifies potential risk.
Driving: Lansoprazole is unlikely to affect the ability to drive or operate machinery. However, if dizziness or visual disturbances occur, patients should avoid these activities.
| Atazanavir, Rilpivirine | PPIs reduce gastric acidity, significantly decreasing the absorption and plasma concentration of these antiretrovirals, leading to loss of virologic response. | Major |
| Clopidogrel | Lansoprazole (a moderate CYP2C19 inhibitor) may reduce the antiplatelet effect of clopidogrel (a prodrug activated by CYP2C19), potentially increasing cardiovascular risk. Consider using an alternative PPI like pantoprazole or ranitidine. | Major |
| Methotrexate | Concomitant use may increase methotrexate serum levels and toxicity (especially with high-dose methotrexate) due to reduced renal clearance. | Major |
| Warfarin | Potential for increased INR and risk of bleeding due to possible interaction. Monitor INR closely when starting or stopping lansoprazole. | Moderate |
| Digoxin | Increased gastric pH may slightly increase the bioavailability of digoxin. Monitor digoxin levels. | Moderate |
| Ketoconazole, Itraconazole | Reduced gastric acidity decreases the absorption of these azole antifungals, reducing their efficacy. Administer antifungals with an acidic beverage or separate dosing. | Moderate |
| Tacrolimus | May increase tacrolimus blood levels. Monitor tacrolimus concentrations. | Moderate |