if you do not find it in sosua try la sirena in POP. there is a health store on the far right, where valentino's ice cream are. they have a good selection of vitamins and supplements, decently priced. i have seen few types of zinc there.
Farmacia Wecare in Ocean Dream Plaza in Cabarete has a good GNC section and will call other pharmacies for you and have what you need delivered there if you don't want to run around.
