There are two sources I looked into before writing this, the first is from Dragon #344 the Elysian Dragons have a cone of "inebriation gas". The second is the rules for getting drunk written in Cityscape (pg 44).
Creatures within the cone of inebriating gas must succeed on a Fortitude save or be sickened for in minutes per age category of the dragon. While under this sickened effect, affected creatures become upbeat and happy, gaining a +1 bonus on saves versus fear effects. Creatures immune to poison are immune to this breath weapon. Some say that the release of the inebriation gas sounds suspiciously like a belch.
Personally, if I was to make such a potion, I'd ignore this and move onto the next bit of source material.
Since you want a potion, and potions are just drinkable spells, we need to craft a spell. Here's my attempt:
Vermouth
Transmutation
Level: Bard 2, Cleric 2, Wizard/Sorcerer 2
Components: V,M
Casting Time: 1 standard action
Range: Close (25ft + 5ft / 2 levels)
Target: One living creature
Duration: 1 hour / 2 level (min 1 hour / max 5 hours)
Saving Throw: Fort partial; See Text
Spell Resistance: Yes
Successfully casting this spell on the target counts as if the creature had consumed [1 / 3 level; min 1 / max 5] drink(s) and resets the duration of a drink's effect (normally an hour) to the duration of the spell. This "drink" counts towards the amount of drinks actually consumed and the effects of this spell itself (multiple casting stack). A creature that successfully saves against this spell does not gain more "drinks" consumed; however, the duration of any drink already consumed (or gained by previous casting of this spell) are reset to the new duration.
Whenever a creature has "consumed" a number of drinks exceeding one-half their Constitution score, they must make a Constitution check. The DC starts at 15 and increases by 1 per additional "drink". Creatures with bonuses against poison can apply them to this check. Creatures immune to poisons need not make this check at all. Each failed Constitution check imposes a cumulative -1 penalty to Dexterity and Wisdom (but does not actually reduce those ability scores) and a cumulative -1 penalty on Constitution checks to avoid further inebriation. A creature's effective Dexterity and Wisdom can't fall below 1 due to inebriation. A creature passes out when the penalty on Constitution check equals their one-half their Constitution score. They remain unconscious for [2d4] hours and are fatigued when they awaken, but the temporary penalties end.