Vonoprazan reversibly inhibits potassium adenosine triphosphatase (H+,K+-ATPase) activity, resulting in a 350-fold reduction in gastric acid secretion compared to standard PPIs.

drug interactions, tacrolimus, vonoprazan

Both vonoprazan and tacrolimus are metabolized by CYP3A4. Tacrolimus concentrations were monitored in 52 renal transplant recipients who switched from rabeprazole to vonoprazan (Mei et al., 2020)[c]. All patients received an extended-release, once-daily tacrolimus formulation with a trough target of 4-2 ng/mL, along with mycophenolate mofetil and methylprednisolone. Mean tacrolimus levels were 1.98 ± 1.02 (ng/mL)/(mg/day) at baseline and 2.19 ± 1.15 (ng/mL)/(mg/day) after conversion (P 0.001). This difference was statistically significant but was not considered clinically significant. Vonoprazan can be safely used in kidney transplant patients receiving tacrolimus.

Vonoprazan blocks gastric acid secretion, thus causing hypomagnesemia due to intestinal malabsorption. A 71-year-old woman presented with generalized tonic-clonic seizures 3 weeks after starting vonoprazan (Aiba et al., 2022) [A]. Laboratory analysis revealed a magnesium level of 0.4 mg/dL, which was thought to be the cause of the patient's seizures. Administration of 5 g of magnesium increased magnesium levels to 2.2 mg/dL, but continued to decrease with continued use of vonoprazan. On hospital day 7, vonoprazan was replaced with famotidine, which stabilized the patient's magnesium concentration at 2.1 mg/dL. Clinicians should monitor for electrolyte abnormalities associated with vonoprazan use, even for short-term use.