[SolomonQ]

Thats the most probable reason for it being more i think, but amount lost depends on pouring techniques and if a pharmacy had 15 addicts on the same methadone type e.g. s/f then most likely all will be prepared in one go in the morning meaning only one rinse of the measuring aparatus is needed minimising wastage and the 20-15ml on top i mentioned above was actually an under-estimate its more like >20ml, and because of the need to keep a running balance the dispenser of methadine would try their hardest to minimize wastage e.g. trying more hard to increase the accuracy of the measurement and to pour out the last drop of methadone back in the bottle before rinsing.

PS running balances are still good practice not obligatory