Acetylcholine is not used commersially because:
Long duration of action
Costly
Rapidly destroyed in the body
Crosses blood brain barrier
[Cl (Rapidly destroyed in the body): Ref: 80KDT,435-BB (93-KDT 6th)Acetylcholine is not used because of evanescent and nonselective action* Acetylcholine injected IV. Does not penetrate blood brain barrier and no central effects are seen.* Acetylcholine has such great importance in the body it is not surprising that attempts have been made to use it in therapeutics, But a substance with a huge variety of effects and so rapidly destroyed in the body is unlikely to be useful when given systemically, as its history in psychiatry illustrates.
A.N.S.