Understanding Vonoprazan and Its Importance
Vonoprazan, sold under brand names like Voquezna, is a newer class of medication called a potassium-competitive acid blocker (P-CAB) [1.5.2]. It is used to treat conditions like erosive esophagitis, gastroesophageal reflux disease (GERD), and to eradicate Helicobacter pylori bacteria in combination with antibiotics [1.6.2, 1.6.3]. Unlike proton-pump inhibitors (PPIs), which require an acidic environment to work, vonoprazan acts more rapidly and has a longer-lasting effect on reducing stomach acid [1.5.1, 1.5.3]. Because of its potent mechanism, being aware of potential interactions and contraindications is vital for patient safety.
Absolute Contraindications: What You Must Avoid
A contraindication is a specific situation in which a drug should not be used because it may be harmful to the person. For vonoprazan, there are two primary contraindications:
- Known Hypersensitivity: Patients who have had a previous allergic reaction to vonoprazan or any of its inactive ingredients must not take the medication [1.2.3, 1.2.8]. Serious reactions, including anaphylactic shock, have been reported [1.2.8].
- Rilpivirine-Containing Products: Concomitant use of vonoprazan with rilpivirine, an antiretroviral medication used to treat HIV, is contraindicated [1.2.1, 1.2.3]. Vonoprazan reduces stomach acidity, which can significantly decrease the absorption and effectiveness of rilpivirine [1.2.1].
Significant Drug Interactions to Be Aware Of
Vonoprazan can interact with numerous medications. It's crucial to inform your doctor and pharmacist of all prescription drugs, over-the-counter medicines, and supplements you are taking [1.2.2].
Drugs Dependent on Gastric pH
By increasing the pH of the stomach (making it less acidic), vonoprazan can alter the absorption of many drugs. The effectiveness of these medications may be reduced.
- Antiretrovirals: Besides the contraindication with rilpivirine, it is recommended to avoid using vonoprazan with atazanavir and nelfinavir [1.2.1, 1.2.3].
- Antifungals: Medications like ketoconazole and itraconazole may have altered absorption [1.2.1, 1.2.6].
- Certain Cancer Drugs: Dasatinib, erlotinib, and nilotinib absorption can be affected [1.2.1].
- Iron Salts: The absorption of iron supplements can be reduced [1.2.1].
- Mycophenolate Mofetil: An immunosuppressant whose absorption may be altered [1.2.1].
Interactions Involving Liver Enzymes (CYP450)
Vonoprazan is primarily metabolized by the liver enzyme CYP3A4 and to a lesser extent by CYP2C19, CYP2B6, and CYP2D6 [1.5.2].
- CYP3A4 Inducers: Drugs that induce this enzyme can decrease the levels and effectiveness of vonoprazan. Examples include rifampin, St. John's wort, phenytoin, and primidone [1.2.4, 1.2.7].
- CYP3A4 Inhibitors: Strong inhibitors like clarithromycin can increase the concentration of vonoprazan [1.2.1].
- CYP3A4 Substrates: As a weak CYP3A4 inhibitor, vonoprazan may increase the levels of other drugs metabolized by this enzyme. Caution is advised with sensitive substrates like tacrolimus, sirolimus, and theophylline [1.2.4].
| Interaction Type | Examples of Drugs to Avoid or Use with Caution | Reason for Concern |
|---|---|---|
| pH-Dependent Absorption | Rilpivirine, Atazanavir, Nelfinavir, Ketoconazole, Iron Salts | Vonoprazan reduces stomach acid, which can decrease the absorption and effectiveness of these drugs [1.2.1]. |
| CYP3A4 Inducers | St. John's Wort, Rifampin, Phenytoin | These can speed up the metabolism of vonoprazan, making it less effective [1.2.4, 1.2.7]. |
| CYP3A4 Substrates | Tacrolimus, Sirolimus, Theophylline, Triazolam | Vonoprazan can slow the metabolism of these drugs, potentially increasing their levels and risk of side effects [1.2.4]. |
Pre-existing Conditions and Other Precautions
Patients should discuss their complete medical history with their healthcare provider before starting vonoprazan.
- Liver or Kidney Disease: Use is not recommended for patients with moderate to severe liver disease or severe kidney disease [1.2.7, 1.2.9]. Dosage adjustments may be needed for those with milder impairment [1.6.9].
- Low Mineral Levels: Inform your doctor if you have low blood levels of magnesium, calcium, or potassium, as long-term use of acid-reducing agents can sometimes cause hypomagnesemia (low magnesium) [1.2.2, 1.3.7].
- Pregnancy and Breastfeeding: The safety of vonoprazan during pregnancy is not well established [1.2.6, 1.3.7]. Patients should not breastfeed while taking vonoprazan and for 2 days after the final dose [1.2.7].
- Long-Term Use Risks: Using vonoprazan for more than a year may increase the risk of fundic gland polyps (abnormal stomach growths) and may make it harder for the body to absorb Vitamin B12 [1.2.2, 1.3.4].
Conclusion
While vonoprazan is an effective medication for acid-related disorders, safety is paramount. The most critical step for any patient is to maintain open communication with their healthcare provider. Always disclose all medications, supplements, and health conditions before starting treatment. Patients should specifically avoid rilpivirine and be cautious with other drugs whose absorption is pH-dependent. Understanding these interactions and contraindications helps ensure that the treatment is both safe and successful.
For more detailed information, you can refer to the FDA's official prescribing information. FDA Prescribing Information [1.6.2]
