With so many athletes streaming in and out of drug rehabilitation centers, it seemed altogether fitting that a pro team would draft someone with a pharmacological background.

Katz conceived of the choice of Dr. Horvitz as a harmless prank among buddies, though the N.B.A., no kibitzers they, quickly checked into it and then declared the chunky backcourt operative ineligible. No reason was given. It is presumed that the N.B.A. officials got their heads together and decided that if no team had drafted him in the previous 26 years, then something must be fishy.

Dr. Horvitz said that if he can't crack the N.B.A., he'd probably go to Italy. ''You can get Guccis there at half-price,'' he said. He's not going anwyhere in basketball, of course, except to his box seat in the Spectrum to watch the N.B.A. champions. Like many fans, though, the doctor is troubled about the drug problems in sports. ''You know, when you're watching a game, you really don't think about the drug problem and it is almost impossible to detect from the stands if someone is taking them,'' he said. ''And if their performance suffers, the team just gets a new player. They're not hurting me as much as they're hurting themselves.

''The tragedy is in the effects the drugs have on the players' lives over a period of years. Drugs are debilitating to the body, and wear it down. So a player shortens his career. But that's not the worst part. From what I understand, the drug habit simply takes over a person's life.''

True, says Dr. Torrey Brown, consultant to the N.B.A. on drug and alcohol problems. ''I have counseled numerous athletes with these problems, and as a general rule they don't play under the influence,'' he said. ''But their addiction is round-the-clock. You become less than you used to be. Not only are you using drugs that act negatively on your body, but you spend most of your time obtaining them - the drugs they use are illegal - and hiding them and worrying about getting the money to pay for them.''