Summary

The interaction between quetiapine and lansoprazole is generally considered minor to moderate, primarily involving potential changes in quetiapine absorption and metabolism. While this combination is commonly prescribed together, monitoring for altered quetiapine effectiveness or side effects may be warranted.

Introduction

Quetiapine (brand name Seroquel) is an atypical antipsychotic medication primarily used to treat schizophrenia, bipolar disorder, and major depressive disorder as an adjunct therapy. It belongs to the dibenzothiazepine class of antipsychotics and works by modulating dopamine and serotonin receptors. Lansoprazole (brand name Prevacid) is a proton pump inhibitor (PPI) commonly prescribed to treat gastroesophageal reflux disease (GERD), peptic ulcers, and other acid-related gastrointestinal conditions by reducing stomach acid production.

Mechanism of Interaction

The interaction between quetiapine and lansoprazole occurs through multiple pathways. Lansoprazole can alter gastric pH by significantly reducing stomach acid production, which may affect the dissolution and absorption of quetiapine, particularly the immediate-release formulation. Additionally, lansoprazole is a mild inhibitor of CYP2D6 and may have minor effects on CYP3A4, enzymes involved in quetiapine metabolism. However, since quetiapine is primarily metabolized by CYP3A4 with CYP2D6 playing a secondary role, the metabolic interaction is generally considered clinically insignificant.

Risks and Symptoms

The clinical risks associated with this interaction are generally low to moderate. Potential concerns include altered quetiapine bioavailability, which could lead to reduced therapeutic effectiveness or, less commonly, increased side effects. Patients may experience changes in mood stabilization, sleep patterns, or psychiatric symptoms if quetiapine levels are significantly affected. The risk is higher in patients taking immediate-release quetiapine formulations compared to extended-release versions. Individual patient factors such as genetic variations in drug metabolism, concurrent medications, and underlying health conditions may influence the interaction severity.

Management and Precautions

Healthcare providers should monitor patients taking both quetiapine and lansoprazole for changes in psychiatric symptoms or quetiapine side effects, particularly during the first few weeks of concurrent therapy. Consider spacing the administration of these medications by 2-4 hours if absorption issues are suspected. Regular psychiatric assessments and symptom monitoring are recommended to ensure therapeutic effectiveness of quetiapine is maintained. If significant interaction effects are observed, alternative acid-suppressing medications (such as H2 receptor antagonists) or quetiapine formulation changes may be considered. Patients should be advised not to adjust doses independently and to report any changes in mood, sleep, or side effects to their healthcare provider promptly.

Quetiapine interactions with food and lifestyle

Quetiapine should not be taken with alcohol as it can increase the risk of drowsiness, dizziness, and impaired coordination. Grapefruit juice may increase quetiapine levels in the blood and should be avoided. Patients should be cautious when driving or operating machinery due to potential sedation effects. Smoking may decrease quetiapine effectiveness, and patients should discuss smoking cessation with their healthcare provider.

Lansoprazole interactions with food and lifestyle

Lansoprazole should be taken on an empty stomach, preferably 30-60 minutes before meals, as food can significantly reduce its absorption and effectiveness. Alcohol consumption should be limited or avoided while taking lansoprazole, as alcohol can increase stomach acid production and counteract the medication's acid-reducing effects. Additionally, alcohol may worsen gastroesophageal reflux disease (GERD) symptoms that lansoprazole is intended to treat.