Methylpentynol sounds like a pretty old drug according to a quick Google search. We're talking about like, a hundred years old...so I wouldn't call it a "new" alcohol alternative, it just looks like an old sedative with a barbiturate-like safety profile...
Check out these resources:
Pharmacology of methylpentynol and methylpentynol carbamate (PubMed)
Oblivion (methylpentynol) - Psychobabble
Toxic Effects and Side-effects of Methylpentynol (PubMed)
I don't like the look of that triple bond, to be honest... human livers and kidneys are not known for processing huge amounts of unsaturated hydrocarbons very well. I could even see it becoming an epoxide somewhere and somehow.