Usage
Lansoprazole is prescribed for the treatment of various gastrointestinal conditions caused by excessive gastric acid secretion. These include:
- Duodenal and gastric ulcers
- Gastroesophageal reflux disease (GERD)
- Erosive esophagitis
- Zollinger-Ellison syndrome (a condition characterized by excessive stomach acid production)
- Helicobacter pylori eradication (in combination with antibiotics)
- NSAIDs (Nonsteroidal anti-inflammatory drugs)-associated gastric ulcers.
Pharmacological Classification: Proton Pump Inhibitor (PPI)
Mechanism of Action: Lansoprazole irreversibly inhibits the H+/K+ ATPase enzyme system (proton pump) in gastric parietal cells. This action effectively blocks the final step of gastric acid production, reducing both basal and stimulated acid secretion.
Alternate Names
While “Lansoprazole” is the generic name internationally recognized, slight spelling variations may exist. Brand names include Prevacid, Zoton FasTab, and Inhibitol.
How It Works
Pharmacodynamics: Lansoprazole suppresses gastric acid secretion by inhibiting the proton pump, leading to a significant reduction in both basal and stimulated gastric acid levels.
Pharmacokinetics:
- Absorption: Lansoprazole is rapidly absorbed after oral administration, reaching peak plasma concentrations within 1.5 to 2.2 hours. The presence of food reduces the bioavailability of the drug.
- Metabolism: Lansoprazole is extensively metabolized in the liver, primarily by the CYP2C19 and CYP3A4 enzymes, to inactive metabolites.
- Elimination: The metabolites are excreted primarily in the urine and bile. The elimination half-life is relatively short, approximately 1.5 hours.
Mode of Action: Lansoprazole, a prodrug, is converted to its active form in the acidic environment of the parietal cell canaliculi. The active form then binds to the proton pump, irreversibly inhibiting its activity.
Receptor Binding/Enzyme Inhibition: Lansoprazole’s primary mechanism is the irreversible inhibition of the H+/K+ ATPase enzyme (proton pump).
Elimination Pathways: Primarily hepatic metabolism via CYP2C19 and CYP3A4, followed by renal and biliary excretion of metabolites.
Dosage
Standard Dosage
Adults:
- 15-30 mg orally once daily for conditions like GERD, duodenal ulcers, and gastric ulcers.
- 60 mg orally once daily for Zollinger-Ellison syndrome, adjustable up to 180 mg/day in divided doses if needed.
Children:
Dosage and usage must be determined by a doctor, depending on age, weight and medical condition. Doses generally start at 15mg/day for children under 30kg, and 30mg/day for those above 30kg or age 12 or older.
Special Cases:
- Elderly Patients: Dose adjustment may be necessary due to age-related decline in renal and hepatic function. Close monitoring recommended.
- Patients with Renal Impairment: No dose adjustment is typically required.
- Patients with Hepatic Dysfunction: A dose reduction (e.g. 50%) is recommended for moderate to severe hepatic impairment.
- Patients with Comorbid Conditions: Dose adjustments may be required based on the specific comorbidity and its potential impact on drug metabolism or clearance. Careful clinical evaluation is crucial.
Clinical Use Cases
Lansoprazole’s role in these settings is primarily for stress ulcer prophylaxis:
- Intubation/Surgical Procedures/Mechanical Ventilation/ICU Use: 30 mg IV once daily is common practice, with dose adjustments as per patient requirements.
- Emergency Situations: IV administration may be preferred for rapid onset of action in acute situations. The dosage will depend on the specific situation and is at the physician’s discretion.
Dosage Adjustments
Dose adjustments are based on individual patient factors such as hepatic impairment, age, and concomitant medications. Genetic polymorphisms in CYP2C19 can influence lansoprazole metabolism and may necessitate dose adjustments.
Side Effects
Common Side Effects:
- Diarrhea
- Constipation
- Abdominal pain
- Nausea
- Headache
Rare but Serious Side Effects:
- Clostridium difficile-associated diarrhea
- Fractures (with long-term use)
- Hypomagnesemia
- Cutaneous lupus erythematosus
- Stevens-Johnson syndrome
Long-Term Effects:
- Vitamin B12 deficiency (with prolonged use)
- Fundic gland polyps
Adverse Drug Reactions (ADR):
Severe allergic reactions (anaphylaxis), severe skin reactions, drug-induced liver injury, rhabdomyolysis.
Contraindications
- Hypersensitivity to lansoprazole or other PPIs.
Drug Interactions
Lansoprazole can interact with several medications, including:
- CYP450 substrates: Lansoprazole inhibits CYP2C19 and may affect the metabolism of drugs like clopidogrel, warfarin, and phenytoin.
- Methotrexate: Concomitant use may increase methotrexate levels.
- Ketoconazole and Itraconazole: Their absorption is reduced when taken with lansoprazole.
- Sucralfate: May decrease lansoprazole absorption. Administer at least 30 minutes apart.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: B (animal studies haven’t demonstrated fetal harm, but human studies are lacking). Use with caution during pregnancy, considering the benefit-risk ratio.
- Breastfeeding: Small amounts are present in breast milk. Potential effects on nursing infants unknown.
Drug Profile Summary
- Mechanism of Action: Irreversible inhibition of the H+/K+ ATPase in gastric parietal cells.
- Side Effects: Diarrhea, constipation, abdominal pain, headache; rarely: C. difficile infection, fractures, hypomagnesemia.
- Contraindications: Hypersensitivity.
- Drug Interactions: Clopidogrel, warfarin, methotrexate, ketoconazole, itraconazole.
- Pregnancy & Breastfeeding: Use with caution in pregnancy; unknown effects on infants during breastfeeding.
- Dosage: Adults: 15-30 mg/day for most conditions; 60-180 mg/day for Zollinger-Ellison syndrome.
- Monitoring Parameters: Monitor for signs of adverse effects, including magnesium levels (for long-term use).
Popular Combinations
- Lansoprazole + amoxicillin + clarithromycin for H. pylori eradication.
- Lansoprazole + naproxen for pain relief with reduced gastrointestinal risk.
Precautions
- General Precautions: Assess for allergies, liver/kidney function before initiating treatment.
- Pregnant Women: Discuss potential risks and benefits with patient.
- Breastfeeding Mothers: Assess risk-benefit ratio.
- Children & Elderly: Consider dose adjustments.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Lansoprazole?
A: Adults: 15-30 mg once daily for conditions like GERD, gastric, and duodenal ulcers. 60-180 mg/day for Zollinger-Ellison syndrome. Pediatric dose needs individualized determination by a doctor.
Q2: How should Lansoprazole be administered?
A: Orally, preferably 30 minutes before a meal, as food may decrease absorption. It can also be given via IV infusion or injection in specific circumstances (e.g., NPO patients).
Q3: What are the common side effects of Lansoprazole?
A: Common side effects include diarrhea, constipation, abdominal pain, nausea, and headache.
Q4: Does Lansoprazole interact with other medications?
A: Yes, Lansoprazole can interact with certain medications, including clopidogrel, warfarin, methotrexate, ketoconazole, itraconazole, and sucralfate.
Q5: Can Lansoprazole be used during pregnancy and breastfeeding?
A: Lansoprazole should be used with caution during pregnancy and breastfeeding, after careful evaluation of the potential risks and benefits by a doctor.
Q6: What is the mechanism of action of Lansoprazole?
A: It irreversibly blocks the proton pump (H+/K+ ATPase) in gastric parietal cells, reducing gastric acid secretion.
Q7: What conditions are contraindicated with Lansoprazole use?
A: Known hypersensitivity to lansoprazole or other PPIs is a contraindication.
Q8: Are there any long-term side effects associated with Lansoprazole use?
A: Potential long-term effects include vitamin B12 deficiency and fundic gland polyps.
Q9: Can Lansoprazole be used in patients with renal or hepatic impairment?
A: No dose adjustment is typically needed for renal impairment. For moderate to severe hepatic impairment, a dose reduction is recommended.
Q10: When should Lansoprazole be taken – morning or evening?
A: Generally, once-daily dosing is recommended in the morning. If twice-daily dosing is prescribed (e.g., for H. pylori eradication), it should be taken once in the morning and once in the evening.
