The Paladin in AD&D 2e has the class ability of Lay on Hands.
A paladin can heal by Laying on Hands. The paladin restores 2 hit points per experience level. He can heal himself or someone else, but only once per day.
Drinking a potion is described as being one of the common and simple actions a character can do in a round (including digging around in a pack for the potion, unstoppering it, etc). Other than doing that in lieu of making an attack, no penalties or disadvantages or vulnerabilities appear to be applicable.
Spell casters in combat can cast spells, but at a risk. Firstly, they get no DEX adjustment to their AC, any successful attack against them spoils the spell, and (IIRC) any threats in melee range get an Attack of Opportunity. Any touch ranged spell the caster wants to apply to an ally who is in melee combat would need to succeed with a hit vs AC 10.
So … is the Paladin's Lay on Hands ability, if used on himself, the same as chugging a potion, or does it trigger all the negatives associated with casting a spell?