It's commonly accepted that most treatments for enteral poisons aren't very useful for alcohol, because it is absorbed so rapidly. For example, by the time a hospital could administer activated charcoal, most likely nearly all of the alcohol would already have passed into the blood. But what about preemptive treatment? If one were to expect a night of heavy drinking, what could be done in advance to decrease absorption and/or limit effects?
So you are searching for hung-over drugs :). I don´t see any problems with that. I have many times wondered the same thing. If you search online one will find hundreds and thousands of journal articles stating "the remedy for hang-over". Of course these "remedies" are based just on folklore.
There is also some scientific literature on this topic. The most comprehensive is a systematic review published 2005 in British Medical Journal.. Unfortunately the authors conclude: "The most effective way to avoid the symptoms of alcohol induced hangover is to practise abstinence or moderation".
I am quite sure that if an effective treatment to reduce or limit the effects of alcohol were to exist, that would have gained popularity beyond any limits.
However, I would present on interesting theory to try. Alcohol or ethanol itself is not the bad guy. Body processes ethanol by oxidating it to acethaldehyde with the help from alcohol dehydrogenase enzyme. The acethaldehyde is responsible for all the bad, including nausea, vomiting etc. It is also a carcinogen associated most importantly to gastric cancer.
To deal with this potential carcinogenity, a Finnish biotechnology Company Biohit has introduced a drug called Acetium. It is a very simple drug, it only contains l-cysteine, an essential amino acid. The trick is that L-cysteine reacts with acethaldehyde forming a compound molecule which has no meaning or effect in human body. As so the Biohit aims to market this product as a pre-emptive treatment for gastric cancer.
But the interesting part if, that is L-cysteine neutralizes acetaldehyde, why could not it therefore be an effective treatment for hangover? Just take some Acetium before drinking and do not worry about the next Morning.
Totally unrelated to the OP. My secret dream is to perform a randomized controlled trial about this idea. Of course, prior to it, I should contact Biohit to make sure that I receive the appropriate rojalties from their sells. Let´s say this treatment really worked in my trial, I would most likely become a multi-billionaire. Alongside I would be responsible for tripling or quadrupling the amount of consumed alcohol around the world since no one would ever suffer from hang-over. People would however get more drunk since this drug only prevents hangover. As so, the rate of homicides, beatings and drunk driving would go thorough the roof. Maybe I should not be waiting any medal from the parliament or president. Perhaps I should abandon my research idea....
I am going to take most of this from my answer to What is the healthiest way to drink excessively and chronically? Most of the advice does not change when we are talking about a one-time scenario instead of a more regular occurrence.
You mention decreasing absorption - an important thing is to get the alcohol to be delivered into the blood (and liver) slowly, definitely. That means eating before drinking, drinking slowly, and not taking any medication that worsens the effect of alcohol.
After the damage is done, so to speak, comes reducing its effects and speeding up recovery. Drink enough additional fluids (water, juices, etc) before, during and after drinking alcohol. Get enough sleep and give your body time to recover.
The paper Interventions for preventing or treating alcohol hangover: systematic review of randomised controlled trials has an overview over various hangover treatments studied in eight publications, from herbal remedies to dietary supplements, but ultimately has to conclude
No compelling evidence exists to suggest that any conventional or complementary intervention is effective for preventing or treating alcohol hangover. The most effective way to avoid the symptoms of alcohol induced hangover is to practise abstinence or moderation
I would suggest for hangover reduction to ensure good hydration before and during the drinking session. Eat some sugar and drink a pint of water before bed. Good idea to ensure that the person has fed well before the session.