Active compounds of Formula (I) are described: wherein: R.sub.1 and R.sub.2 are each independently C1-C4 alkyl; or R.sub.1 and R.sub.2 together form a C2-C7 alkylene chain; and Z is a non-steroidal anti-inflammatory drug (NSAID); along with pharmaceutically acceptable salts and prodrug thereof, and methods of using the same.