So taking niacinamide before drinking would be wise? What about thiamine (as you have written in the past) plus niacinamide before drinking?
Both are good. Alcohol depletes thiamine and this is what causes the infamous Wernicke-Korsakoff syndrome. Niacinamide is precursor to NAD and the NAD is needed to metabolize alcohol by alcohol and aldehyde dehydrogenases. So, taking both and maybe a little B2 and B6 (hello Energin) would be even better. I think B6 directly deactivates acetaldehyde and is useful in many pathologies with a build up of aldehydes.