Pharmacology Which of the following is naturally occurring tertiary amine and lipid-soluble reversible anticholinesterases: A Physostigmine. B Neostigmine. C Pyridostigmine. D All of the above. 💡 Explanation Which of the following is naturally occurring tertiary amine and lipid-soluble reversible anticholinesterases: ✓ Correct Answer: A. Physostigmine.