Introduction
Lansoprazole is a proton pump inhibitor (PPI) that suppresses gastric acid secretion by specifically inhibiting the H+/K+ ATPase enzyme system at the secretory surface of gastric parietal cells. It is widely prescribed for various acid-related gastrointestinal disorders and is available in both prescription and over-the-counter formulations.
Mechanism of Action
Lansoprazole is a substituted benzimidazole that accumulates in the acidic compartment of parietal cells, where it undergoes conversion to active sulfenamide metabolites. These metabolites form covalent disulfide bonds with cysteine residues on the H+/K+ ATPase proton pump, irreversibly inhibiting acid secretion. The drug effectively blocks the final step of gastric acid production, resulting in prolonged suppression of both basal and stimulated acid secretion.
Indications
- Healing of erosive esophagitis
- Maintenance of healed erosive esophagitis
- Symptomatic gastroesophageal reflux disease (GERD)
- Healing of duodenal ulcers
- Maintenance of healed duodenal ulcers
- Treatment of gastric ulcers
- Helicobacter pylori eradication (in combination with antibiotics)
- Pathological hypersecretory conditions (Zollinger-Ellison syndrome)
- Reduction of risk of NSAID-associated gastric ulcers
Dosage and Administration
Adults:- GERD: 15-30 mg once daily for up to 8 weeks
- Erosive esophagitis: 30 mg once daily for up to 8 weeks
- Maintenance of healed esophagitis: 15 mg once daily
- Duodenal ulcer: 15 mg once daily for 4 weeks
- H. pylori eradication: 30 mg twice daily with amoxicillin and clarithromycin for 10-14 days
- NSAID-associated ulcer risk reduction: 15 mg once daily
- Hepatic impairment: Consider dose reduction in severe liver disease
- Renal impairment: No dose adjustment necessary
- Geriatric patients: No dose adjustment necessary
- Pediatric patients: Dosing based on weight (1-1.5 mg/kg/day)
- Take 30 minutes before meals
- Swallow capsules whole; do not crush or chew
- Alternative administration: Capsule may be opened and contents sprinkled on applesauce or mixed with juice
Pharmacokinetics
Absorption: Rapidly absorbed with peak plasma concentrations occurring within 1.7 hours. Bioavailability is approximately 85% and is decreased by food. Distribution: Protein binding is 97%, primarily to albumin. Volume of distribution is approximately 0.5 L/kg. Metabolism: Extensively metabolized in the liver via cytochrome P450 enzymes (primarily CYP2C19 and CYP3A4) to inactive metabolites. Elimination: Primarily excreted in urine (14-23%) and feces (approximately 50%). Elimination half-life is 1-2 hours, but duration of acid suppression persists for 24-48 hours due to irreversible binding to proton pumps.Contraindications
- Hypersensitivity to lansoprazole or any component of the formulation
- Concomitant use with rilpivirine-containing products
- Patients taking drugs that are highly dependent on CYP2C19 for clearance and have narrow therapeutic windows
Warnings and Precautions
- Bone fracture: Long-term PPI use associated with increased risk of osteoporosis-related fractures of hip, wrist, or spine
- Hypomagnesemia: Reported with prolonged PPI use; monitor magnesium levels
- Clostridium difficile-associated diarrhea: Increased risk with PPI use
- Acute interstitial nephritis: May occur at any time during therapy
- Vitamin B12 deficiency: Long-term use may lead to malabsorption of vitamin B12
- Cutaneous and systemic lupus erythematosus: New onset or exacerbation reported
- Fundic gland polyps: Associated with long-term PPI use
Drug Interactions
- Clopidogrel: Reduced antiplatelet effect due to CYP2C19 inhibition
- Methotrexate: Increased methotrexate levels possible
- Warfarin: Increased INR monitoring recommended
- Ketoconazole, itraconazole, iron salts: Reduced absorption due to increased gastric pH
- Digoxin: Potential increased bioavailability
- Tacrolimus: Increased tacrolimus levels
- CYP2C19 substrates: Increased levels of drugs metabolized by CYP2C19
Adverse Effects
Common (≥1%):- Headache (3-4%)
- Diarrhea (3-4%)
- Abdominal pain (2-5%)
- Nausea (1-3%)
- Constipation (1-2%)
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
- Acute interstitial nephritis
- Clostridium difficile-associated diarrhea
- Hypomagnesemia
- Bone fracture
- Vitamin B12 deficiency
Monitoring Parameters
- Symptom improvement and resolution
- Endoscopic healing when indicated
- Magnesium levels with prolonged use
- Renal function with long-term therapy
- Bone density assessment with long-term use in high-risk patients
- Vitamin B12 levels with prolonged therapy
- Complete blood count with long-term use
- Signs of lupus erythematosus
Patient Education
- Take medication 30 minutes before meals for optimal effectiveness
- Do not crush or chew capsules; swallow whole
- Report any signs of allergic reaction (rash, itching, swelling)
- Notify healthcare provider if experiencing persistent diarrhea, abdominal pain, or bloody stools
- Be aware of potential bone fracture risk with long-term use
- Discuss need for calcium and vitamin D supplementation with prolonged therapy
- Inform all healthcare providers of lansoprazole use, especially before starting new medications
- Do not discontinue abruptly without medical guidance
References
1. Micromedex® [Internet]. Truven Health Analytics. Lansoprazole. 2. Lexicomp® [Internet]. Wolters Kluwer Health. Lansoprazole. 3. Shin JM, Sachs G. Pharmacology of proton pump inhibitors. Curr Gastroenterol Rep. 2008;10(6):528-534. 4. Katz PO, Gerson LB, Vela MF. Guidelines for the diagnosis and management of gastroesophageal reflux disease. Am J Gastroenterol. 2013;108(3):308-328. 5. FDA Prescribing Information: Prevacid (lansoprazole). 6. Strand DS, Kim D, Peura DA. 25 years of proton pump inhibitors: A comprehensive review. Gut Liver. 2017;11(1):27-37. 7. Savarino V, et al. Proton pump inhibitors: Use and misuse in the clinical setting. Expert Rev Clin Pharmacol. 2018;11(11):1123-1134.