Lansoprazole is a proton pump inhibitor (PPI) that suppresses gastric acid secretion by irreversibly inhibiting the H+/K+-ATPase (“proton pump”) within parietal cells of the stomach. After absorption and transport into the acidic canaliculi of parietal cells, lansoprazole is protonated and converted to its active sulfenamide form, which covalently binds cysteine residues on the pump. Because the inhibition is irreversible, acid production remains reduced until new pumps are synthesised, allowing once-daily dosing for most indications despite a relatively short plasma half-life (≈1–2 hours).
By profoundly reducing basal and stimulated acid secretion, lansoprazole promotes healing of acid-related mucosal injury (e.g., peptic ulcers, erosive oesophagitis) and improves symptoms such as heartburn and epigastric pain. PPIs are generally more effective than H2-receptor antagonists for healing and maintenance therapy in gastro-oesophageal reflux disease (GORD/GERD) and duodenal/gastric ulcers. They are also essential components of Helicobacter pylori eradication regimens and are used to prevent upper GI bleeding in high-risk settings (e.g., NSAID therapy in susceptible patients).
Lansoprazole is available as delayed-release capsules or orally disintegrating tablets (ODT) designed to protect the drug from acid degradation. It can be given before meals (usually before breakfast). Granules from certain capsule products can be administered via nasogastric tube when mixed with appropriate fluids as per product instructions. While generally well tolerated, long-term or high-dose PPI use is associated with specific safety considerations that warrant periodic review of indication and dose (see Warnings & Precautions).
Administration: Take before a meal (preferably before breakfast). Swallow capsules whole or open and sprinkle granules on soft food without chewing, following product instructions.
Most side effects are mild and self-limiting. Patients should report persistent diarrhoea, severe abdominal pain, signs of low magnesium (muscle cramps, palpitations), or symptoms of infection.
Discuss a step-down strategy once symptoms are controlled (on-demand use, lowest effective dose, or trial of H2-blocker) to minimise long-term exposure where appropriate.
Lansoprazole alters gastric pH and is metabolised by CYP3A4 and CYP2C19, leading to both pharmacodynamic and pharmacokinetic interactions.
Always provide a full list of medicines and supplements to your clinician and pharmacist. Avoid starting new OTC NSAIDs for dyspepsia without advice, as they may worsen GI risk.
Overdose: Lansoprazole overdoses are generally well tolerated; symptoms may include headache, dizziness, flushing, or abdominal discomfort. There is no specific antidote; management is supportive. Seek medical advice for large ingestions or concerning symptoms.
Accidental double dose: Usually low risk. Do not take extra doses to “catch up.” Monitor for unusual symptoms; seek advice if unwell.
Missed dose: Take as soon as remembered unless it is near the time for the next dose, in which case skip the missed dose and resume the usual schedule. Do not double up.
Read the patient leaflet and follow your prescriber’s instructions. Persistent or severe symptoms should prompt medical review.
If using ODTs or granules, follow the leaflet for preparation and administration (e.g., sprinkling on soft food or giving via feeding tube) to ensure full dose delivery.
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