I know my husband and know what he is like socially (2-3 beer guy) and if he isn't messaging me then something is weird. If I didn't hear from him I would have gone to where he was because I would have been worried something happened such as a fall or a car accident. We don't track each other's phones but we tell each other where we are going and often message each other and let the other know when we are leaving. If nobody answered the door I would have thought it was odd and thought they drank too much and passed out. I would have pounded on the door and then the windows. I would be mad. I would never think he had been doing drugs and overdosed. I would probably go home mad to wait it out but then when morning came I would start to really worry then go back and do the same thing. I can't say when I would involve the police or if I would even think of breaking in because it's a hypothetical question. If anything I would worry it was carbon monoxide poisoning inside the house or something.
It's funny how different people are, no way would I go home mad to wait (maybe I would in two weeks when the meds kick in fully and I'm not severely anxious, I'll get back to you on that). But that's what makes people interesting and why we are all different.