I found an intriguing article, about alcohol metabolism, which raises an interesting point. The Rate of absorption and metabolism are different and largely unrelated.
When alcohol is consumed, it passes from the stomach and intestines into the blood, a process referred to as absorption. Alcohol is then metabolized by enzymes, which are body chemicals that break down other chemicals.
To whit, alcohol is absorbed faster than it is being metabolised. Any poison that behaves the same would in large enough concentrations overwhelm Captain America and leave him in a drunken stupor, for a while.
The number of 'drinks' increases (1-4) as you go from line to line.
The upwards portion is the absorption taking place, as you see it's mostly the same gradient (steepness) between drinks, each one just gets higher before being taken down by those enzymes in an exponential decay. So for Captain America, only the downward slope would be steeper, and take about a quarter of the time for those enzymes to kick in.
Lets say, Captain America is pretty happy, he's saved the world and after some sweet Shawarma with tony he goes for some drinks. Trying to keep up with Tony he tanks, 4 pints.
Instead of the peak being at 1 hour, it's at quarter of an hour, and as it's the decay that starts earlier the peak is much lower (around 30%), and reaches ~0% at 1hr 45min. This means something that should take him up to 80%, is only 30%, which wikipedia leads me to believe is barely noticeable.
So yes, he could be intoxicated, even lethally. But you'd need a lot more of that toxin to have an effect.