Lansoprazole

Generic Name: Lansoprazole
Pharmacological Class: Proton pump inhibitor (PPI)
Therapeutic Class: Antiulcer agent / acid suppressant
ATC Code: A02BC03
Common Brand Names: Prevacid, Zoton, Zoton FasTabs, Lansoprazole Teva, Takepron
Legal Status: Prescription-only in most countries; some formulations available OTC

Available Forms:
– Capsules (15 mg, 30 mg)
– Orodispersible tablets (FasTabs, SoluTabs)
– Granules for oral suspension
– Intravenous powder (limited availability)

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Mechanism of Action

Lansoprazole is a prodrug that selectively and irreversibly inhibits the H⁺/K⁺-ATPase enzyme (the "proton pump") in the gastric parietal cells.

• This action blocks the final step of acid production in the stomach.

• It significantly reduces both basal and stimulated gastric acid secretion.

• It requires acidic activation in the parietal cell canaliculi, where it is converted to its active sulfenamide form.

This pharmacological effect makes lansoprazole highly effective in healing and preventing acid-related gastric and duodenal mucosal injury.

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Indications

Gastrointestinal Disorders:

1. Gastroesophageal Reflux Disease (GERD):
   – Healing of erosive esophagitis
   – Maintenance therapy in chronic GERD
   – Symptomatic GERD (non-erosive reflux)

2. Peptic Ulcer Disease:
   – Duodenal ulcer treatment (4–8 weeks)
   – Gastric ulcer healing
   – NSAID-induced ulcer prophylaxis and treatment

3. Helicobacter pylori Eradication:
   – In triple therapy regimens with antibiotics (e.g., lansoprazole + clarithromycin + amoxicillin or metronidazole)

4. Zollinger-Ellison Syndrome:
   – Gastrin-secreting tumor causing severe hyperacidity
   – High-dose PPI maintenance

5. Stress Ulcer Prophylaxis (hospitalized, critically ill patients – IV formulation)

6. Eosinophilic Esophagitis (off-label use in some regions)

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Dosage and Administration

Adults:

• GERD (erosive esophagitis):
  30 mg once daily for 4–8 weeks

• GERD (maintenance):
  15–30 mg once daily

• Duodenal ulcer:
  15 mg once daily for 2–4 weeks

• Gastric ulcer:
  30 mg once daily for 4–8 weeks

• H. pylori eradication (triple therapy):
  – 30 mg twice daily with
  – Clarithromycin 500 mg twice daily
  – Amoxicillin 1 g twice daily
  – For 7–14 days

• Zollinger-Ellison Syndrome:
  Initial dose 60 mg/day; may increase to 120–180 mg/day in divided doses

Pediatrics (where approved):

• 1–11 years: 15–30 mg once daily depending on weight and indication

• 12–17 years: Dosing similar to adults

Administration Tips:

• Administer before meals, preferably in the morning

• Do not crush or chew delayed-release capsules or orodispersible tablets

• SoluTab/FasTab may be dissolved in water or placed on the tongue

• For patients with swallowing difficulty: Open capsule and sprinkle granules on applesauce/yogurt

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Pharmacokinetics

• Absorption: Rapid, peak plasma concentration in 1.5–2 hours

• Bioavailability: ~80% after multiple doses

• Protein Binding: ~97%

• Metabolism: Hepatic (CYP2C19, CYP3A4) to inactive metabolites

• Half-Life: 1–2 hours (acid suppression lasts >24 hours)

• Excretion: Renal (urine) and fecal routes

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Contraindications

• Known hypersensitivity to lansoprazole, substituted benzimidazoles, or excipients

• Concomitant use with rilpivirine (due to reduced absorption of this HIV drug)

• Phenylketonuria caution with orodispersible formulations (contain aspartame)

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Warnings and Precautions

1. Long-term use risks:

   • Vitamin B12 deficiency (gastric acid is needed for absorption)

   • Hypomagnesemia (especially with diuretics or long-term therapy)

   • Osteoporosis-related fractures (hip, wrist, spine)

   • Chronic kidney disease / interstitial nephritis

   • Gastric atrophy and gastric cancer risk with H. pylori infection

2. Clostridioides difficile–associated diarrhea:
   – Risk increases with long-term acid suppression

3. Masking of gastric malignancy:
   – Symptom relief may delay diagnosis
   – Investigate alarm symptoms (e.g., weight loss, vomiting, anemia)

4. Lupus erythematosus:
   – Cutaneous and systemic forms have been reported with PPIs

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Adverse Effects

Common (>1%):

• Headache

• Diarrhea

• Abdominal pain

• Constipation

• Nausea

• Dizziness

• Flatulence

Uncommon (0.1–1%):

• Rash, pruritus

• Insomnia

• Dry mouth

• Peripheral edema

• Arthralgia

Rare (<0.1%):

• Interstitial nephritis

• Hepatitis, jaundice

• Severe skin reactions (e.g., Stevens-Johnson syndrome)

• Anaphylaxis

• Hypomagnesemia

• Bone fractures (with prolonged use)

• Blood dyscrasias (leukopenia, thrombocytopenia)

• QT prolongation (especially with hypokalemia or in CYP2C19 poor metabolizers)

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Drug Interactions

Interacting Drug or Class	Interaction Description
Clopidogrel	Lansoprazole may reduce activation via CYP2C19 inhibition (less than omeprazole)
Ketoconazole, itraconazole	Decreased absorption due to reduced gastric acidity
Digoxin	Slight increase in digoxin bioavailability
Methotrexate	Delayed clearance at high doses
Warfarin	Slight INR changes; monitor if co-administered
HIV drugs (rilpivirine, atazanavir)	Reduced absorption due to pH-dependent solubility
Tacrolimus	Increased levels (especially in transplant patients)

Lansoprazole is a moderate inhibitor of CYP2C19 and substrate of CYP3A4, which underlies most interactions.

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Pregnancy and Lactation

Pregnancy:

• Category B (FDA) – Animal studies show no fetal risk; no adequate human data

• Generally considered safe in pregnancy if clinically necessary

Breastfeeding:

• Unknown if excreted in breast milk

• Use caution; omeprazole may be preferred due to better data

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Comparison with Other PPIs

Parameter	Lansoprazole	Omeprazole	Esomeprazole	Pantoprazole	Rabeprazole
Onset of action	Fast	Moderate	Moderate	Moderate	Fast
CYP2C19 impact	Moderate	High	Low	Minimal	Minimal
Formulations	Dispersible	Capsules	Capsules	Tablets	Tablets
Acid control	Strong	Strong	Strong	Moderate	Strong
Cost	Low	Low	Moderate	Moderate	Low

Lansoprazole has a fast onset, multiple formulations (especially orodispersible), and is generally well-tolerated.

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Monitoring Parameters

• Symptom resolution (e.g., heartburn, ulcer pain)

• Magnesium, calcium, and vitamin B12 in long-term use

• Renal function (if used chronically)

• Liver function tests if elevated baseline LFTs

• H. pylori test of cure if used in eradication therapy

• Signs of serious GI pathology in patients with warning symptoms

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Patient Counseling Points

• Take before meals, usually once daily in the morning

• Do not crush or chew capsules; use orodispersible forms if needed

• May take several days to reach full effect; not for immediate relief

• Inform provider if using other drugs affected by stomach acid

• Do not self-treat for >2 weeks without evaluation

• Report persistent diarrhea, abdominal pain, or rash

• Store at room temperature, protected from moisture

• Avoid alcohol and NSAIDs if being treated for ulcers