Lansoprazole vs omeprazole: comparing two leading PPIs

Proton pump inhibitors (PPIs) are among the most widely prescribed medicines in the UK.

Both lansoprazole and omeprazole belong to this class and work by the same fundamental mechanism.

How PPIs work:

PPIs irreversibly inhibit the hydrogen-potassium ATPase enzyme system (the "proton pump") on the surface of parietal cells in the stomach lining.

This is the final step in acid secretion, and blocking it reduces gastric acid production by approximately 90 to 95% at full doses.

Common indications:

• Gastro-oesophageal reflux disease (GORD): the most common reason for PPI prescriptions
• Peptic ulcer disease: both gastric and duodenal ulcers
• Helicobacter pylori eradication: PPIs are a core component of triple therapy regimens
• NSAID gastroprotection: preventing stomach damage in patients on long-term anti-inflammatory medicines
• Zollinger-Ellison syndrome: a rare condition of excess acid production

PPIs available in the UK:

• Omeprazole (Losec)
• Lansoprazole (Zoton)
• Esomeprazole (Nexium)
• Pantoprazole (Protium)
• Rabeprazole (Pariet)

Omeprazole and lansoprazole are the two most commonly prescribed PPIs in UK primary care, accounting for the vast majority of PPI prescriptions.

Multiple clinical trials and systematic reviews have compared lansoprazole and omeprazole across various conditions.

For GORD and oesophagitis:

• Both lansoprazole 30 mg and omeprazole 20 mg produce healing rates of approximately 85 to 95% for erosive oesophagitis at 8 weeks
• Head-to-head studies have generally found no statistically significant difference in healing rates
• Some studies suggest lansoprazole may provide slightly faster symptom relief in the first 1 to 2 days, likely due to its faster absorption

For peptic ulcers:

• Duodenal ulcer healing rates at 4 weeks: approximately 90 to 95% for both medicines
• Gastric ulcer healing rates at 8 weeks: approximately 85 to 90% for both
• No clinically meaningful difference has been demonstrated

For H. pylori eradication:

• Both are effective as the PPI component of triple therapy
• Standard regimens: PPI plus amoxicillin plus clarithromycin (or metronidazole) for 7 days
• Eradication rates are comparable at approximately 80 to 85%

For NSAID gastroprotection:

• Both are recommended by NICE for patients at risk of NSAID-related upper GI complications
• Lansoprazole 15 to 30 mg and omeprazole 20 mg are considered equivalent for this purpose

The BNF does not express a preference between the two for any indication. NICE guidance on GORD similarly treats them as interchangeable first-line options.

While both medicines work by the same mechanism, there are subtle pharmacological differences that may be relevant for some patients.

Onset of action:

• Lansoprazole: reaches peak plasma concentration in approximately 1.5 to 2 hours
• Omeprazole: reaches peak plasma concentration in approximately 1 to 3 hours
• Lansoprazole may provide marginally faster symptom relief, though this is rarely clinically significant

Bioavailability:

• Lansoprazole bioavailability is approximately 80 to 90%, which is slightly higher than omeprazole at approximately 35 to 60%
• Omeprazole's bioavailability increases with repeated dosing as the medicine inhibits its own metabolism

Metabolism:

• Both are metabolised in the liver by the cytochrome P450 system
• Omeprazole is primarily metabolised by CYP2C19 and CYP3A4, making it more susceptible to drug interactions
• Lansoprazole is also metabolised by CYP2C19 and CYP3A4, but to a lesser extent and with less impact on other medicines

Equivalent doses:

• Lansoprazole 30 mg is broadly equivalent to omeprazole 20 mg
• Lansoprazole 15 mg is broadly equivalent to omeprazole 10 mg
• For maintenance therapy, lansoprazole 15 mg and omeprazole 10 to 20 mg are standard

Formulations:

• Omeprazole: capsules, dispersible tablets (MUPS), intravenous infusion
• Lansoprazole: capsules, orodispersible tablets (useful for patients with swallowing difficulties)

One of the most clinically important differences between lansoprazole and omeprazole relates to their potential for drug interactions.

Omeprazole interactions:

• Clopidogrel: omeprazole inhibits CYP2C19, the enzyme that converts clopidogrel to its active metabolite. The MHRA advises avoiding the combination of omeprazole with clopidogrel because it may reduce clopidogrel's antiplatelet effect, potentially increasing the risk of cardiovascular events
• Methotrexate: omeprazole may increase methotrexate levels, particularly at high doses
• Phenytoin and warfarin: omeprazole can increase levels of both, requiring monitoring
• Citalopram and escitalopram: omeprazole may increase levels of these SSRIs via CYP2C19 inhibition

Lansoprazole interactions:

• Lansoprazole has a weaker inhibitory effect on CYP2C19 and is generally considered safer to use with clopidogrel, though the BNF still advises caution
• The MHRA recommends lansoprazole or pantoprazole as alternative PPIs for patients who need gastroprotection alongside clopidogrel
• Lansoprazole has fewer clinically significant interactions overall

Shared interactions:

• Both reduce the absorption of medicines that require an acidic stomach environment, including ketoconazole, itraconazole and some HIV medicines
• Both may reduce the absorption of oral iron supplements

For patients on multiple medicines, lansoprazole may be the preferred choice due to its lower interaction potential.

The side effect profiles of lansoprazole and omeprazole are very similar, reflecting their shared mechanism of action.

Common side effects (both medicines):

• Headache: reported by approximately 3 to 7% of patients
• Nausea and diarrhoea: usually mild
• Abdominal pain: typically self-limiting
• Flatulence and bloating
• Dizziness

Uncommon side effects:

• Skin rashes
• Dry mouth
• Altered taste
• Joint pain

Long-term risks (shared by all PPIs):

The MHRA and NICE have highlighted potential risks of prolonged PPI use:

• Bone fractures: long-term PPI use is associated with a small increased risk of osteoporotic fractures, particularly of the hip, wrist and spine
• Hypomagnesaemia: low magnesium levels can develop with prolonged use, causing muscle cramps, tremor and cardiac arrhythmias. The BNF recommends checking magnesium levels if treatment is expected to last beyond 12 months
• Clostridium difficile infection: reduced stomach acid may increase susceptibility to gut infections
• Vitamin B12 deficiency: reduced acid secretion impairs B12 absorption over time
• Rebound acid hypersecretion: stopping a PPI abruptly after long-term use may cause a temporary rebound in acid production, worsening symptoms

Both medicines are generally well tolerated for short-term use. Long-term use should be reviewed regularly, and patients should be on the lowest effective dose.

For most patients, the choice between lansoprazole and omeprazole comes down to practical and clinical factors rather than dramatic efficacy differences.

Choose lansoprazole if:

• The patient is taking clopidogrel (to avoid the CYP2C19 interaction)
• The patient has swallowing difficulties and would benefit from orodispersible tablets
• There are concerns about drug interactions with other CYP2C19 substrates
• The patient has tried omeprazole and experienced side effects

Choose omeprazole if:

• The patient is already stable on omeprazole with no issues
• A dispersible formulation for nasogastric tube administration is needed (omeprazole MUPS)
• Cost is a primary consideration (omeprazole is marginally cheaper, though both are very affordable)
• The patient has no significant drug interactions

NHS prescribing considerations:

• Both are available as inexpensive generic preparations
• Monthly costs are typically under 2 pounds for either medicine
• NICE does not preferentially recommend one over the other for standard indications
• Local formularies may express a preference based on cost or availability

The most important question:

Regardless of which PPI is chosen, the BNF and NICE emphasise that the need for ongoing treatment should be reviewed regularly. Many patients are prescribed PPIs for longer than necessary.

Stepping down to a lower dose or stopping altogether (with a gradual taper) should be considered at each review.