Lansoprazole

Introduction Overview

Generic Name

lansoprazole

Brand Name

FIRST Lansoprazole, Prevacid

Dosage Form

oral capsules, orally disintegrating tablets, oral suspension (liquid)

Drug Class

Proton pump inhibitors

Pharmacokinetics

Absorption:
Lansoprazole is rapidly absorbed following oral administration, with peak plasma concentrations typically occurring within 1.5 hours post-dose. The absolute bioavailability of lansoprazole ranges between 80% to 90% after oral dosing. Food intake can reduce the rate but not the extent of absorption; hence, it is generally recommended to administer lansoprazole before meals to maximize plasma levels and therapeutic efficacy. The drug is acid-labile and formulated with enteric coatings to prevent degradation in the stomach acid, ensuring delivery to the intestine where absorption occurs.

Distribution:
Once absorbed, lansoprazole is extensively distributed throughout the body. It exhibits a moderate volume of distribution approximately 0.3 to 0.4 L/kg. The drug is highly protein-bound, approximately 97%, primarily to albumin and alpha-1-acid glycoprotein, which facilitates distribution and may modulate its tissue penetration. Distribution to gastric parietal cells is crucial as it targets the H+/K+-ATPase pumps localized there.

Metabolism:
Lansoprazole undergoes extensive hepatic metabolism primarily via the cytochrome P450 enzyme system, predominantly CYP3A4 and CYP2C19 isoenzymes. The drug is metabolized into inactive metabolites by sulfoxide and hydroxylation pathways. Genetic polymorphisms affecting CYP2C19 can alter the metabolism rate, leading to variable plasma levels and clinical response among different individuals and ethnic groups. Metabolism is a key determinant of its plasma half-life and duration of action.

Elimination:
The elimination half-life of lansoprazole is approximately 1.5 hours, but its acid suppression effect persists longer due to irreversible inhibition of the proton pump. The metabolites are primarily excreted in the urine (approximately 70%) and to a lesser extent via feces (around 30%). The drug undergoes enterohepatic recirculation to a limited degree. In patients with hepatic impairment, clearance may be reduced warranting dose adjustment. There is no significant renal clearance of unchanged drug, so renal insufficiency minimally affects pharmacokinetics.

Overall, lansoprazole demonstrates pharmacokinetic properties that allow once-daily dosing with sustained acid suppression. The enteric-coated formulation, extensive hepatic metabolism, high protein binding, and acid labile nature are critical features influencing its clinical use and dosing considerations.

Dosage Forms

Available Dosage Forms:
- Oral delayed-release capsules: 15 mg, 30 mg
- Orally disintegrating tablets (ODT): 15 mg, 30 mg
- Oral suspension (lansoprazole for suspension): 3 mg/mL concentration (provided in packets or bottles)

Dosages for Adults and Adolescents:
- Treatment of GERD and erosive esophagitis: 15-30 mg once daily for 4 to 8 weeks
- Duodenal ulcer treatment: 15 mg once daily for 2 to 4 weeks
- Helicobacter pylori eradication (in combination with antibiotics): 30 mg twice daily for 7 to 14 days
- Zollinger-Ellison syndrome: 60 mg daily initially, adjusted according to clinical response, up to 180 mg daily in divided doses
- Over-the-counter Prevacid OTC for frequent heartburn: 15 mg once daily for 14 days

Specific Patient Populations:
- Pediatric use: Oral suspension indicated for children 1 year and older for treatment of duodenal ulcers
- Elderly: No specific dosage adjustment necessary but caution advised due to comorbidities
- Hepatic impairment: Dose reduction may be required due to decreased metabolism
- Renal impairment: No dosage adjustment needed
- Pregnancy and breastfeeding: Use only if clearly needed after risk-benefit assessment

Clinical guidelines recommend administration before meals, usually before breakfast, to optimize acid suppression. For oral suspension, proper shaking and measuring devices should be used to ensure accurate dosing. Capsules should be swallowed whole without crushing or chewing. Orally disintegrating tablets should be allowed to dissolve on the tongue without chewing or swallowing whole. Treatment duration varies by indication and patient response, with maintenance therapy considerations in chronic cases.

Mechanism Of Action

Lansoprazole is a proton pump inhibitor (PPI) that exerts its therapeutic effect by selectively and irreversibly inhibiting the H+/K+ ATPase enzyme system—the proton pump—in the parietal cells of the stomach. This enzyme catalyzes the final step in the secretion of gastric acid into the gastric lumen. By binding covalently to the cysteine residues on the proton pump, lansoprazole blocks the exchange of hydrogen ions and potassium ions, thereby suppressing gastric acid secretion regardless of the stimuli (whether histamine, acetylcholine, or gastrin-mediated).

The drug is a weak base that requires activation in the acidic environment of the secretory canaliculi of the parietal cells. After oral administration, it is absorbed into the systemic circulation and diffuses into the acidic milieu of activated parietal cells, where it converts to its active sulfenamide form. This reactive intermediate then forms disulfide bonds with the proton pump, leading to prolonged inhibition of acid secretion. This mechanism contributes to a sustained reduction in gastric acidity, allowing healing of acid-related mucosal damage.

Compared to histamine H2-receptor antagonists which competitively inhibit histamine receptors, lansoprazole inhibits the proton pump directly and irreversibly, resulting in a more profound and longer-lasting suppression of gastric acid production. This pharmacodynamic profile allows for once-daily dosing in most indications. The delayed onset of effect relative to acid-neutralizing agents such as antacids is due to the requirement for active proton pumps and systemic absorption.

Clinical studies have demonstrated that lansoprazole effectively raises gastric pH and maintains it above 4.0 for prolonged periods, facilitating ulcer healing and symptom relief in conditions such as gastroesophageal reflux disease (GERD), erosive esophagitis, Zollinger-Ellison syndrome, and Helicobacter pylori eradication regimens. Ongoing research continues to explore its effect on gastric mucosal protection and its potential impact on gastric microbiome and long-term use complications.

Pharmacological Actions

Selective and irreversible inhibition of the gastric H+/K+ ATPase proton pump in parietal cells.
Suppression of basal and stimulated gastric acid secretion, raising gastric pH.
Reduction of gastric acid-mediated mucosal injury and promotion of healing in erosive esophagitis and peptic ulcers.
Synergistic action with antibiotics for H. pylori eradication due to acid suppression enhancing antibiotic efficacy.
Sustained acid suppression enabling once-daily dosing in acid-related disorders.
Demonstrates acid labile prodrug characteristics converted in acidic environment to active inhibitor.
Minimal central nervous system penetration, limiting systemic adverse effects.
Influences gastric motility indirectly via acid inhibition, potentially reducing symptoms of reflux.
Has gastroprotective effects by decreasing pepsin activation through acid suppression.
May affect absorption of certain nutrients (e.g., vitamin B12, magnesium) due to lowered stomach acidity over long-term use.
Potential to induce fundic gland polyps in chronic high dose usage through mucosal cellular proliferation.
Metabolized extensively by CYP450 enzymes, leading to clinically significant drug-drug interactions.
Does not significantly inhibit cytochrome P450 enzymes but may affect plasma levels of CYP2C19 substrates.
Exhibits low potential for direct cardiotoxicity or hepatotoxicity at therapeutic doses.
Effectively reduces symptoms of acid-related disorders improving patient quality of life.

Therapeutic Or Clinical Uses

Treatment and maintenance of gastroesophageal reflux disease (GERD) including erosive esophagitis.
Healing and prevention of gastric and duodenal ulcers.
Management of Zollinger-Ellison syndrome and other pathological hypersecretory conditions.
Eradication of Helicobacter pylori infection when used in combination with appropriate antibiotics.
Treatment of erosive esophagitis caused by acid reflux damage.
Relief of frequent heartburn symptoms occurring two or more days per week (OTC indication).
Prevention of gastric ulcers in patients on long-term nonsteroidal anti-inflammatory drug (NSAID) therapy.
Treatment of gastric hypersecretion secondary to other medical conditions (e.g., systemic mastocytosis).
Symptomatic treatment of gastroesophageal reflux symptoms refractory to H2 antagonists.
Adjunct therapy to protect the gastric mucosa and reduce acid-related tissue injury.
Management of erosive esophagitis to improve esophageal mucosal healing.
Part of combination therapy to reduce risk of recurrent ulcers in patients with previous ulcer history.
Prevention of acid-related complications in patients undergoing endoscopy or surgery requiring acid reduction.

Side Or Adverse Effects

Nausea and mild to moderate abdominal pain or discomfort.
Diarrhea, which may occasionally signify Clostridium difficile-associated colitis.
Constipation and flatulence as gastrointestinal disturbances.
Headache, including migraine exacerbation.
Rare hypersensitivity reactions including urticaria, angioedema, and anaphylaxis.
Risk of fundic gland polyps with long-term administration.
Potential vitamin B12 deficiency with therapy longer than three years.
Hypomagnesemia presenting with tremors, muscle spasms, seizures, and arrhythmias in prolonged use.
Increased risk of bone fractures (hip, wrist, spine) especially with long-term or high-dose use.
Rare kidney-related adverse effects, including interstitial nephritis and chronic kidney disease.
New onset or worsening symptoms of systemic lupus erythematosus (joint pain, photosensitive rash).
Seizures reported infrequently in patients with magnesium disturbances.
Gastrointestinal infections due to alteration of gastric pH and microbiota balance.
Potential dizziness and fatigue reported anecdotally.
Elevated liver enzymes in rare cases during therapy.

Precautions

Use cautiously in patients with a history of liver disease due to hepatic metabolism.
Monitor magnesium levels during prolonged therapy or when used with other drugs causing hypomagnesemia.
Assess bone health status and consider supplementation in patients at risk for osteoporosis.
Avoid simultaneous administration with sucralfate; separate dosing by at least 30 minutes.
Use with caution in patients with lupus erythematosus; monitor for symptom exacerbation.
Avoid self-medication for frequent heartburn beyond recommended OTC duration without physician advice.
Advise patients not to crush or chew capsules or orally disintegrating tablets to maintain drug efficacy.
Consider dose adjustment or alternative therapy in patients with CYP2C19 polymorphisms affecting metabolism.
Screen for and monitor vitamin B12 deficiency during long-term treatment exceeding one year.
Report symptoms suggestive of kidney impairment promptly, including reduced urine output and hematuria.
Exercise caution if combined with methotrexate or rilpivirine-containing products due to interaction risks.
Contraindicate lansoprazole in children under 1 year; no safety data available.
Advise pregnant or breastfeeding women to consult healthcare provider prior to use.
In patients with low gastric acid states, consider risk of infections including Clostridium difficile.
Monitor for signs of allergic reactions, especially in prone individuals.

Warnings

May cause kidney problems, including interstitial nephritis; report decreased urination or hematuria immediately.
Can provoke diarrhea that may indicate a serious infection such as Clostridium difficile colitis.
Risk of new or worsening lupus symptoms; monitor for joint pain and sun-sensitive rash.
Increased risk of bone fractures (hip, wrist, spine) with long-term or multiple daily dosing.
Delayed onset of action; not suitable for immediate heartburn relief.
Long-term use (over 3 years) associated with vitamin B12 deficiency requiring monitoring.
Use with caution in patients taking sucralfate; separate dosing by at least 30 minutes to ensure absorption.
Allergic reactions including anaphylaxis have been reported; seek emergency care if symptoms occur.
Overuse or repeated 14-day treatment courses without physician guidance is discouraged.
Potential interactions with methotrexate may increase toxicity; close monitoring advised.
Heartburn may mimic cardiac events; patients with chest pain should seek emergency care to exclude heart attack.
OTC use not recommended in patients with alarming symptoms such as black stools, unexplained weight loss, or prolonged symptoms.
Phenylalanine content in some formulations requires caution in patients with phenylketonuria.
Risk of seizures reported in patients with marked hypomagnesemia induced by chronic use.
Supratherapeutic doses or overdose require emergency medical attention to prevent complications.

Contraindication

Known hypersensitivity or allergy to lansoprazole or any proton pump inhibitors.
Concurrent use with rilpivirine-containing products (e.g., Edurant, Complera, Odefsey) due to reduced antiviral efficacy.
Children under 1 year of age; safety and efficacy not established for this age group.
Use contraindicated in patients with unexplained persistent gastrointestinal symptoms without physician evaluation.
Patients with phenylketonuria should avoid formulations containing phenylalanine.
Not for immediate relief of heartburn symptoms; contraindicated for on-demand acute therapy.
Patients with bleeding disorders where acid suppression may exacerbate underlying risks should be cautious.
Known hypersensitivity to any excipients present in formulations.
Contraindicated in individuals with history of allergic-type reactions to other substituted benzimidazoles.
Should not be administered with drugs that have severe interactions altering lansoprazole pharmacokinetics without proper clinical supervision.

Drug Interactions

Sucralfate significantly decreases lansoprazole absorption; administer lansoprazole at least 30 minutes before sucralfate.
Methotrexate clearance may be reduced by lansoprazole, increasing risk of toxicity; monitor closely during coadministration.
Rilpivirine-containing antiretroviral drugs have reduced plasma levels when coadministered with proton pump inhibitors; contraindicated combination.
Lansoprazole may alter absorption of other drugs dependent on acidic gastric pH such as ketoconazole, atazanavir, and iron salts.
Possible interaction with warfarin and other anticoagulants may increase bleeding risk; monitor INR accordingly.
Clopidogrel activation may be impacted due to CYP2C19 inhibition by some proton pump inhibitors, though clinical significance with lansoprazole is less defined.
Concurrent use with digoxin may increase digoxin plasma concentration due to altered gastric pH and absorption.
Interaction with diazepam and phenytoin owing to CYP metabolism pathways; monitor therapeutic levels as necessary.
Drugs requiring acidic gastric environment for optimal absorption such as calcium carbonate or ampicillin may have decreased bioavailability.
Concomitant use with St. John's Wort may reduce lansoprazole effectiveness via CYP induction.
Potential interactions with clopidogrel require clinical judgment regarding cardiovascular risk and bleeding risk balancing.
Use caution when combined with other CYP2C19 substrates due to competitive metabolism.
Gastric acid suppression affects absorption and bioavailability of enteric-coated formulations of certain drugs.
Herbal products and vitamins altering CYP450 enzymes may alter lansoprazole pharmacokinetics.
Close monitoring required when combining with drugs that prolong QT interval to assess arrhythmia risk.

Preparations Of The Drug

FIRST Lansoprazole oral delayed-release capsules in 15 mg and 30 mg strengths for prescription use.
Prevacid capsules containing enteric-coated granules for delayed release to protect active drug from gastric acid.
Prevacid SoluTab orally disintegrating tablets available in 15 mg and 30 mg doses facilitating administration without water.
Lansoprazole oral suspension (likely 3 mg/mL) formulated for pediatric and adult patients unable to swallow capsules, includes dosing syringe for accurate measurement.
Over-the-counter Prevacid OTC 15 mg delayed-release capsules for treatment of frequent heartburn in adults.
Packaging includes appropriate child-resistant closures and instructions for preparation and administration.
Packets or bottles for oral suspension requiring shaking prior to dosing to ensure uniform drug distribution.
Excipients include buffers to maintain drug stability and flavor agents in oral suspension to improve palatability.
Some formulations may contain phenylalanine; labeling includes caution for patients with phenylketonuria.
Available as single-use packets or multi-dose bottles depending on formulation and indication.
Formulations designed to optimize bioavailability by protecting drug from acid degradation and targeting absorption in the small intestine.