bump from work
Cimetidine apppears to chelate zinc, calcium and magnesium. In your body, they are usually divalent cations, i.e. they lost 2 electrons so they are ions with a +2 positive charge. There must be electrical neutrality in ionic solutions, so they are in equilibrium with one or more negative ions, i.e. anions, such as hydroxide ions, chloride ions, carbonate ions, etc.
That's just in case you need some refreshing in your chemistry. I doubt if Rockingham does.