While I totally agree with nzseries1, (like I usually do) I can understand your bit of confusion.
Is the medicinal product strongly presumed or strongly effective? You have to ask yourself what the purpose in your sentence is going to be.
Either word would take an adverb. In this instance, strongly makes more logical sense to modify presumed.
If it's a good product, then it would also be strongly effective, but it wouldn't be as logical to use that word choice to make your point. You'd want to choose a more visually appropriate word. I say visually to mean it creates the right word picture in your mind.
You'd probably use words like: extremely effective, very effective, quite effective. You wouldn't use these words to modify presumed.
But the confusion occurs (for me) because strongly here almost fits both words.