That sounds very strange. I'm trying to think of a mechanism that could be involved in blocking endocytosis of the virus... I supposed I can read the paper and see what the authors say.
If you read the study, you’ll see that other drugs had significant effect, though none with as much effect as amiodarone (Cordarone).
The ones that stuck out were theophylline and ECGC, which had almost as much effect as verapamil. So drink a lot of green tea...