Medications for rate control
Most β-blockers can be safely used with investigational COVID-19 medications. Verapamil is P-glycoprotein (P-gp) related and metabolized by CYP3A4-type cytochrome P450-dependent enzymes (Table 2). Since HCLQ exerts impact on hyperpolarization-activated current Ifmodulation in sinoatrial node and atrioventricular node cells, co-administration of verapamil and HCLQ may cause bradycardia and conduction disturbance.37Digoxin is well-known for its narrow therapeutic range.38Moreover, investigational COVID-19 medications which consist of substrate of CYP3A4 and P-gp, such as HCLQ, may potentially increase digoxin level and its toxicity, resulting in conduction disturbance.39Therefore, ECG monitoring for bradycardia and conduction disturbance should be considered.