The FDA has approved vonoprazan, a potassium-competitive acid blocker, copackaged with amoxicillin (Voquezna Dual Pak – Phathom) and with amoxicillin and clarithromycin (Voquezna Triple Pak) for treatment of Helicobacter pylori infection in adults. Vonoprazan is the first potassium-competitive acid blocker to be approved in the US. It has been available in Japan for treatment of various acid-related disorders since 2014. Vonoprazan is not available alone in the US.

The FDA recently cleared the AmpliChip CYP450 Test (Roche), which analyzes blood-derived DNA to detect genetic variations in the activity of cytochrome P450 (CYP) enzymes CYP2D6 and CYP2C19 and determines the metabolizer status of the patient. The test is intended to help guide clinicians in prescribing individualized drug therapy. About 25% of all drugs, including many antidepressants and antipsychotics, are substrates of either CYP2D6 or CYP2C19. The test is being promoted initially to psychiatrists.

The FDA has warned that use of the macrolide antibiotic clarithromycin (Biaxin, and generics) may increase the risk of cardiovascular morbidity and mortality in patients with heart disease.

View the Inhibitors and Inducers of CYP Enzymes, P-Glycoprotein, and Other Transporters tables

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

The FDA has required the manufacturer of Plavix, an antiplatelet drug used in addition to aspirin to prevent cardiovascular events in high-risk patients,1 to add a boxed warning to the package insert about the risk of a poor response to the drug in patients with genetic polymorphisms of the cytochrome P450 enzyme CYP2C19. Clopidogrel is a prodrug and CYP2C19 is mainly responsible for its bioactivation. The Medical Letter reported last year that several studies have found higher rates of cardiovascular events, including stent thrombosis, in patients with these polymorphisms taking...

About 2.5 million persons in the US had hepatitis C between 2017 and 2020. Guidelines from the American Association for the Study of Liver Diseases (AASLD) and the Infectious Diseases Society of America (IDSA) on management of hepatitis C virus (HCV) infection were updated in 2023.

With the removal of Vioxx from the market and concerns about cardiovascular toxicity with other selective COX-2 inhibitors, patients are looking for safe alternatives, and manufacturers of other drugs are looking for additional market share. The COX-2 inhibitors first became popular because they have less upper GI toxicity than older less selective NSAIDs, at least in the short term, in patients not taking aspirin.

The FDA has approved ticagrelor (Brilinta – AstraZeneca), an oral antiplatelet drug, for use with low-dose aspirin to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome (ACS). It will compete with clopidogrel (Plavix) and prasugrel (Effient) for such use. Clopidogrel is expected to become available generically in the US within the next few months.

The FDA has approved the subcutaneously injected interleukin (IL)-4 receptor alpha antagonist dupilumab (Dupixent – Sanofi/Regeneron) for treatment of eosinophilic esophagitis (EoE) in patients ≥12 years old who weigh ≥40 kg and treatment of prurigo nodularis in adults. Dupilumab is the first drug to be approved in the US for each of these indications. It is also FDA-approved for treatment of atopic dermatitis, asthma, and chronic rhinosinusitis with nasal polyposis.