You found a way to kill a Japanese honeysuckle shrub?
Please share it with us! They are invasive exotics and are a menace. In many parts of US they are taking over the landscape. They out-compete because they are the first to leaf out in the spring and the last to lose their leaves in the fall. So they choke everything else out. And they are nearly indestructible. You can cut the whole thing off at ground level and it will spring right back up. You can do that twice a year forever and you will never have killed it. They hardly ever get diseases or pests.
If you mean it is dropping leaves on the lower part of the stems, I would guess that means it is pruned so that the top part is widest and is shading out what is underneath. That doesn't mean the shrub is dead or dying, just that those leaves aren't getting any light. You can correct that by better pruning so that it is wider at the bottom.