He needs to go back to the doc and get a proper briefing on what these are and how they work. I believe they are a brand name for Gliclazide, and that they aim to reduce blood sugar levels by improving insulin response in the body. Side effects include the possibility of hypoglycaemia, where blood sugar goes TOO low and can be dangerous. So your pal needs to see the doc if he doesn't understand his medication.
greenave - welcome to the forum. Zircon is gliclazide, normally gliclazide is available in 20mg and 80mg tablets, but Bristol Meyers brought out a 40mg tablet and called it Zircon.
Here you can find out more http://drugs.webmd.boots.com/drugs/drug ... cTac=false
But really I would advise your friend asks his doctor or nurse for information on any medicines he/she has been prescribed.