Lidocaine + Nirmatrelvir / ritonavir

MediHelp rates the interaction as major. Lidocaine and Nirmatrelvir / ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ritonavir is a potent CYP3A4 inhibitor and can substantially raise lidocaine exposure, particularly with systemic dosing. This may cause CNS toxicity and arrhythmias, and the product labeling advises caution with antiarrhythmic drugs such as lidocaine.

MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid systemic lidocaine if feasible, or use reduced doses with ECG monitoring and lidocaine concentrations where available. Standard local anesthetic doses can usually be used with attention to total dose and toxicity symptoms.

MediHelp also lists interactions of Lidocaine with, for example, Bupivacaine liposome, Disopyramide, Ex vivo expanded autologous human corneal epithelial cells containing stem cells. The full list is on the Lidocaine page.