I noticed no one replied. Sorry about that so I'll add my two cents of what I know.

My SO has used a rx for ED but for different reasons. First problem he had was that he combined it with alcohol! Major no no!!! No other drugs or alcohol should be used.

I do know that the drug is not supposed to make sex last longer per say, not like marathon sex, but to engage in sex again within a reasonable time frame. Easier to get an erection again.

I'd treat the situation just like any other & not change anything just bec he's using a drug.
Maybe just see how it goes the first few times & go from there.

I know if one has a side effect that there's others to choose from.
Enjoy!