Maybe you’ve passed a storefront business called a “compounding pharmacy” and wondered about the difference between it and retail and chain pharmacies such as CVS, Walgreens, Costco, Publix and other independent pharmacies. According to the American Pharmacists Association at pharmacist.com, “Of the approximately 56,000 community- based pharmacies in the United States, about 7,500 pharmacies specialize in compounding services.”