Coadministration has not been studied. Amlodipine is metabolized by CYP3A4. Nirmatrelvir/ritonavir is predicted to increase amlodipine exposure by ~2-fold based on drug-drug interactions studies with amlodipine and indinavir/ritonavir or paritaprevir/ritonavir leading to the recommendation to reduce amlodipine dosage by 50% or to take the dose every other day. However, a dose adjustment can be optional in the case of amlodipine given that patients can be advised to monitor for symptoms of hypotension and to temporarily pause the antihypertensive drug if needed. If the dose is adjusted, the usual dose of amlodipine should be resumed 3 days after the last dose of nirmatrelvir/ritonavir as the inhibitory effect of ritonavir is expected to last up to 3 days after completing nirmatrelvir/ritonavir.