Do whatever you can to make him drink that formula. Until 12months of age a baby should have some formula or breast milk for medical reasons which are the same as why a child should not have real milk until 12 months of age.
My daughter didn't have a problem taking or giving up her bottle but she did have trouble giving up milk/formula actaully. She would drink milk/formula but nothing else. At 11 months I started weaning and did 3/4 formula and 1/4 milk then 1/2 and 1/2 then 1/4 Form and 3/4 milk then all milk week by week until 12 months when she was on 100% milk. She took it ina sippy cup.
My suggestion would be to take him to the store adn let him pick out a sippy cup, get him very excited that he picked out this sippy cup and jsut be very thrilled and excited when he uses it. (Or try a different brand that perhaps he would adapt to better)
He needs liquids! Good luck!
@}~>~~