Blackout after only having 1 drink

I remember serving myself 1 drink and as soon as I finished it I blacked out. Everyone said I was beyond drunk and falling down several times. It was a premixed bacardi cocktail from a bottle and I drank only 6 ounces. Is it possible to blackout from only 1 drink? I have drank 10-12 drinks in 1 night and never experienced a blackout like this from only 1 drink and I have drank this same cocktail before and drank 6 cups of it and didn’t even get me tipsy.