Drug test KSA

None that I know off. Test like that are done only during the process of getting a residency permit. If you are not coming to do any health related works and just pure business like meeting up with clients and checking products etc. I do not think a 4 days trip here would involve any drug test. You should be ok.

However I did advice to at least try not to use or smoke it for 24 hours before your journey. A little smell might start a wild fire for you.

They don't do drug tests on arrival or departure.  It is a rare event. 

Also, to correct the previous poster, there are NO drug tests done for residency permits either.  They are only testing for infectious diseases.

The way it happens (and I know of someone who had it happen to them in UAE):

You arrive, look suspicious or attract customs attention
They pull you aside and search your luggage - find nothing
You still arouse suspicion or bad mouth them
They do a swab test of your belongings
It comes back positive for drugs
They are still unable to find the drugs in your belongings
They put you through a body scan and / or do a blood test
It comes back positive and that is it

So as you can see, there are many many steps before this happens.  I wouldn't worry and just be careful not to get any residue on you or your luggage.