While the prices of 28 packs have been increased, ranging from 0.96 per cent to 19.72 per cent, the prices for 12 packs have been revised downwards from their existing level with decrease ranging from 17.24 per cent to 85.44 per cent, a NPPA spokesperson said on Friday.The new prices would become effective within 15 days fron the date of notification in the official Gazette. In the case of 4 formulations, the prices have been fixed for the first time, the ceiling price for 16 other packs have been revised.