Guanidine hydrochloride, usually abbreviated GuHCl and sometimes GdnHCl or GdmCl, is the hydrochloride salt of guanidine.it has a strong basic compound with parasympathomimetic activity.Guanidine hydrochloride enhances the release of acetylcholine following a nerve impulse and potentiates acetylcholine actions on muscarinic and nicotinic receptors.