Compounds of the formula (I): ##STR1## or a pharmaceutically acceptable salt thereof, wherein: R.sup.1 is cycloalkyl of 5 to 7 carbon atoms; aryl of 6 to 10 carbon atoms unsubstituted or substituted by straight or branched chain alkyl of 1 to 4 carbon atoms, halo or trifluoromethyl; or ##STR2## wherein A is oxygen, sulfur or NR.sup.5, wherein R.sup.5 is hydrogen, straight or branched chain alkyl of 1 to 4 carbon atoms or halo, and R.sup.6 is hydrogen, straight or branched chain alkyl of 1 to 4 carbon atoms or halo;R.sup.2 is straight or branched chain alkyl of 1 to 4 carbon atoms or cycloalkyl of 5 to 7 carbon atoms; andR.sup.3 and R.sup.4 are the same or different and each is hydrogen; straight or branched chain alkyl of 1 to 8 carbon atoms unsubstituted or substituted by hydroxy, acyloxy of 2 to 5 carbon atoms, carboxyl or carbamoyl;are useful for treating pain, inflammation and fever in humans and animals.