NO Way JOSE!
Holiday=Lots of Visitors=SALES
Most farmacias are open on Sunday and are open until about 7 or so. Some on Revolucion are open 24 hours. Finding ones open wont be a problem.
Graneros (vet supply stores) are also open on Sundays . One I know of is open to 7 or 8 7 days a week. The only holidays they are closed are Xmas, easter,ect. They arent closed on turkey day b/c they dont give a shit about the Pilgrims-lol.
Email me if you need some info.