There is סם רפואי tho, which declares a drug medical. Anyway, I think when the context is medical, one can infer סם refers to a medicine, however expresses the meaning of a strong drug for pain-killing, anesthesia, and the like - not a medicine. Otherwise, סם refers to cocaine/hero.
It is fairly rare in this use. Actually the only way I would think a sentence like that will be said in a real situation is an autopsy of an ODed person.
In medical use a doctor would say התרופה הזאת מנמיכה את לחץ הדם.