Dose - Why can my friend now take >3ml of GBL?

[Synesthesiac]

Hi all,

My mates been probably overdooing the GBL a bit recently, probably having a drink of it in the evening every other day or so. The thing that he says he has noticed is that the dosage he needs to get the same effects has drastically increased. He used to only need 2ml to get really wobbly and drunk, now to get the same its about 3ml, which he can down in one go. He even had 3.6ml the other day over the space of about 20-30 minutes, and surprisingly even this large dosage still did not really produce the same effedcts it used to. A few months ago this dosage would have sent him straight to sleep.

So is there an issue with tollerance and GBL? Are any other peoples dosages this high?

Thanks.