In general, if you have two drugs that inhibit AChE, if this were their only mode of action, it would be reasonable to expect similar effects. However, seldom do two drugs have exactly the same pharmacological profile, which can be due in part to their actions on other targets. In addition, you need to consider the pharmacokinetics. For example, you need to consider the tissue distribution of inhibition and the time-course of inhibition. Note that huperzine A is a tight-binding inhibitor whereas physostigmine carbamylates the active site serine. However, the carbamylated serine can be reactivated by aqueous hydrolysis to regenerate the active enzyme.

Thank you very much for your reply Dr. RIchardson.  So It is highly unlikely that Huperzine A will lower somatostatin and increase GH as physostigmine has been show to do in research.  I am wanting to file a report with the FDA against a supplement company who is claiming their huperzine A product does in fact reduce somatostatin and increase GH based on 4 studies they list that are all done on physostigmine.  Again, I do appreciate your response.

https://www.ncbi.nlm.nih.gov/pubmed/16508314 this may be what you initially found.

I found nothing similar about Huperzine A.

Huperzine A

SMILES: C\C=C1\[C@@H]2CC3=NC(O)=CC=C3[C@@]1(N)CC(C)=C2

PubChem  https://pubchem.ncbi.nlm.nih.gov/compound/907504

STITCH: http://stitch.embl.de/cgi/network.pl?taskId=udog70gWyQun

ChEMBL https://www.ebi.ac.uk/chembl/compound/inspect/CHEMBL1255901

Ironically, the nearly 400 bioactivities from ChEMBL resolve to Acetylcholinesterase or Butyrylcholinesterase (once you filter for lack of activity etc.)

Physostigmine

SMILES: CNC(=O)OC1=CC=C2N(C)[C@H]3N(C)CC[C@@]3(C)C2=C1

https://pubchem.ncbi.nlm.nih.gov/compound/5983

DrugCentral entry http://drugcentral.org/drugcard/2159/view?q=physostigmine

STITCH  http://stitch.embl.de/cgi/network.pl?taskId=zUb7B1Mq7piY

ChEMBL https://www.ebi.ac.uk/chembl/compound/inspect/CHEMBL94

Their chemical structure isn't remotely similar:

TANIMOTO similarity using MACCS keys (the druglike ones): 0.4 (so in 2D, not similar).

In 3D, using ROCS, the Tanimoto Combo score is 0.831 (not that high, max is 2). 

The only bioactivity they share in common is on cholinesterases.

Note that STITCH has very different profiles for the two molecules, though much of that is inferred from literature co-assocations.  

Although PubChem quotes DrugBank several times, Huperzine A is not an FDA approved drug (though I believe you know that). Enjoy this link as well.

http://www.fda.gov/ICECI/EnforcementActions/WarningLetters/ucm198452.htm

Apparently FDA does take aim at unsubstantiated claims!!!

IN SHORT: I would not expect that Huperzine A would have the same actions on Somatostatin. 

WOW!  Thank you very much for all of this great information Dr. Oprea.  Yes the study you liked to, Rubin et al 2006 was one of the 4 he had linked to his web site.  This guy is selling a product using MK677 and huperzine for a ridiculous price.  He outright claimed that the MK677 causes rises in somatostatin thus shutting down GH pulses and the huperzine a would keep this from happening.   I am surely not an expert in this field as you are but do understand the basic actions of the two substance and figured that there is most likely no connection between the two.  Even the studies on alzheimer's are pretty sketchy.  I will start putting together this information that you and Dr. Richardson have graciously provided and turn it over to the FDA.  I can't stand scammers that take advantage of athletes.  This industry is literally full of them.  Again, I appreciate all of the valuable information you have provided me.

Dr.Opera here are the links to the studies this company is using:

References:

1. https://www.ncbi.nlm.nih.gov/pubmed/8432781

2. https://www.ncbi.nlm.nih.gov/pubmed/9404449

3. https://www.ncbi.nlm.nih.gov/pubmed/1347008

Good luck. As I showed in one of the links, the FDA definitely takes seriously such false claims. I applaud your efforts to debunk unsubstantiated claims.