Out of two anticholinesterases, drug 'X' is a teiary amine while drug 'Y' is a quaernary ammonium compound. Then
Drug X is physostigmine and Drug Y is neostigmine. Physostigmine:- It is rapidly absorbed from g.i.t. and parenteral sites. Applied to the eye, it penetrates cornea freely. It crosses blood-brain barrier and is disposed after hydrolysis by ChE. Neostigmine and congeners:- These are poorly absorbed orally; oral dose is 20-30 times higher than parenteral dose. They do not effectively penetrate cornea or cross blood-brain barrier. They are paially hydrolysed and paially excreted unchanged in urine. Ref:- kd tripathi; pg num:-107,108