Voquezna (vonoprazan) is a potassium-competitive acid blocker (P-CAB) used to treat conditions like erosive esophagitis and H. pylori infection. Unlike proton pump inhibitors (PPIs), it doesn't require activation by stomach acid and can provide rapid and sustained acid suppression. However, this powerful effect on stomach acidity, combined with its metabolism by liver enzymes, means Voquezna can have significant drug interactions.
How drug interactions with Voquezna occur
Interactions with Voquezna primarily happen through two main mechanisms:
- Altered Gastric pH: As an effective acid blocker, Voquezna significantly raises the pH inside the stomach. This can dramatically reduce the absorption of drugs that require an acidic environment to be absorbed properly.
- Enzyme Metabolism: Voquezna is metabolized by cytochrome P450 (CYP) enzymes in the liver, primarily CYP3A4 and CYP2C19. Other medications that inhibit or induce these enzymes can either increase Voquezna's concentration (raising the risk of side effects) or decrease its concentration (making it less effective).
Medications to Avoid with Voquezna
Some medications are explicitly contraindicated or strongly advised against for use with Voquezna due to the high risk of serious interactions.
- Rilpivirine-containing products: This is a direct contraindication. Voquezna significantly lowers the effectiveness of antiretroviral drugs containing rilpivirine, which can lead to HIV drug resistance.
- Certain HIV Medications: The antiretrovirals atazanavir and nelfinavir should be avoided because Voquezna can decrease their absorption and efficacy.
- Certain Antifungals: Itraconazole and ketoconazole require stomach acid for proper absorption. Voquezna can make these drugs less effective, and concurrent use should be carefully managed.
- Strong CYP3A Inducers: Medications that speed up the CYP3A4 enzyme, such as the antiepileptic drugs carbamazepine and phenytoin, can cause Voquezna to be broken down too quickly, reducing its effectiveness.
Significant Interactions Requiring Careful Monitoring
For other medications, concurrent use is possible but requires close supervision by a healthcare provider. Adjustments to dosage or timing may be necessary.
- Clopidogrel (Plavix): Voquezna can reduce the effectiveness of this antiplatelet drug, potentially increasing the risk of blood clots. Alternative antiplatelet therapies may be considered.
- Citalopram and Cilostazol: Voquezna inhibits the CYP2C19 enzyme, which can increase the blood levels of these drugs. This increases the risk of side effects, and dose adjustments may be needed.
- Tacrolimus and Cyclosporine: These immunosuppressants are metabolized by CYP3A4. Voquezna's inhibition of this enzyme can increase their concentration, raising the risk of toxicity.
- Digoxin and Diuretics: Voquezna treatment can lead to low magnesium levels (hypomagnesemia). This can increase the toxicity of drugs like digoxin and is more likely to occur with long-term use or in combination with diuretics.
- Iron Supplements: The absorption of iron salts can be decreased by Voquezna's acid-reducing effects. Patients should discuss managing iron supplementation with their doctor.
- Antibiotics (Amoxicillin and Clarithromycin): Voquezna is often prescribed as part of a combination therapy for H. pylori. The antibiotics included (especially clarithromycin) have their own extensive lists of drug interactions and contraindications that must be considered.
Comparison Table: Common Voquezna Interactions
| Drug Type | Example Drug(s) | Interaction Mechanism | Result of Interaction | Recommended Action |
|---|---|---|---|---|
| HIV Medications | Rilpivirine, Atazanavir, Nelfinavir | Altered gastric pH | Decreased drug effectiveness, risk of HIV resistance | AVOID rilpivirine; AVOID atazanavir/nelfinavir |
| Antifungals | Itraconazole, Ketoconazole | Altered gastric pH | Decreased antifungal effectiveness | Monitor efficacy; adjust timing/dose as directed |
| Antiplatelets | Clopidogrel | CYP2C19 inhibition | Reduced antiplatelet effect, risk of blood clots | Monitor effectiveness; consider alternative therapy |
| Antidepressants | Citalopram | CYP2C19 inhibition | Increased citalopram levels and side effect risk | Monitor for side effects; dose adjustment may be needed |
| Immunosuppressants | Tacrolimus, Cyclosporine | CYP3A4 inhibition | Increased immunosuppressant levels and toxicity risk | Monitor drug levels closely; dose adjustment may be needed |
| Herbal Supplements | St. John's Wort | CYP3A4 induction | Decreased Voquezna effectiveness | AVOID St. John's wort |
| Anti-seizure Drugs | Carbamazepine, Phenytoin | CYP3A4 induction | Decreased Voquezna effectiveness | Monitor; alternative treatment may be required |
Non-Prescription Interactions
Even without a prescription, some over-the-counter and herbal products can interfere with Voquezna. St. John's wort, for example, is a known inducer of the CYP3A4 enzyme, and its use is strongly discouraged. Patients taking iron supplements should discuss potential reduced absorption with their doctor. Cannabis and CBD products have not been extensively studied but should be discussed with a healthcare provider before concurrent use.
Conclusion
While Voquezna is an effective treatment for acid-related conditions, its potential for significant drug interactions is a crucial consideration for patient safety. The medication's impact on gastric pH and its metabolism via CYP enzymes necessitate a thorough review of all other medications, supplements, and herbal products a person is taking. It is never advisable to self-diagnose or self-treat. To ensure the safe and effective use of Voquezna, patients must maintain open communication with their healthcare providers and pharmacists.
For more detailed information, consult the official FDA prescribing information for Voquezna and its combination packs.
Diagnostic Test Interactions
Voquezna can also interfere with certain lab tests, leading to false results. It may cause false-positive results for Chromogranin A (CgA) tests for neuroendocrine tumors and the secretin stimulation test for gastrinoma. If these tests are necessary, Voquezna should be temporarily discontinued at least 14 to 28 days beforehand to ensure accurate results.
Summary of key considerations for safe use
- Contraindicated Medications: Do not take Voquezna with any product containing rilpivirine, or with atazanavir or nelfinavir.
- Gastric pH-Dependent Drugs: Inform your doctor if you take drugs like itraconazole, ketoconazole, or iron salts, as Voquezna can impair their absorption.
- Enzyme-Metabolized Drugs: Be cautious with drugs like clopidogrel, citalopram, and tacrolimus, as Voquezna affects their metabolism via CYP enzymes.
- Herbal Supplements: Avoid St. John's wort, which can reduce Voquezna's effectiveness.
- Combination Packs: When using Voquezna Dual or Triple Pak, be mindful of additional interactions from amoxicillin and clarithromycin.
- Full Disclosure: Always provide your doctor and pharmacist with a complete list of all your medications and supplements before starting Voquezna.
