I have a high tolerance to codeine and tramadol and i took methadone for the first time the other week i took 30mg first and then a further 15mg 4 hours later which wasnt a good idea....i would suggest you take 25mg/ml max which will get you pretty wasted and give you great pain relief if you want this from it ad methadone stays in your sytsem for 24hours plus and by that point the dose you took 24 hours before will be half the strength so if you were to re take some more you would only need half of what you took the night befiore to get as high....but be careful wuith it it is very addictive if taken to regularly and also if you take to much there is a very serious risk of OD'ing so take small amounts first, if you dont feel anything form your first dose give it upto 4 hours because it takes ages to kick in and then after 4 hours if nothing happens i wouldnt take anymore than 10ml more max, i took an extra 15mg because the nice gouch had wore off after 4hours but it hadnt actually it was just the strongest part whcih had so wen i took an extra 15mg it tipped me over the edge and i got no sleep and kept thinking i had to tell myself to breathe, funny looking back but at the time wasnt to nice, enjoy and be safe !