The MRP of most of the medicines is uncontrolled. Big hospitals taking advantage of this get special brands designed for them and get the MRP printed at their own sweet will and in connivance with the pharma industry. To give you an example, the antibiotic piperacillin and Tazobactum combination is sold at ₹ 799- 899 in these hospitals, whilst the same antibiotics by other reputed companies is available for ₹200/- only.
There is almost a compulsion for the patients to buy these from internal pharmacy, because if you are lucky to get prescription, the brand that the hospital will ask will surely be not available outside, and even if you bring a comparable brand either they will not accept it or refuse it under the pretext of quality concerns etc.