the only one of the GiantsГў priligy and cialis together Within this sub group of compounds and sub groups, preferences and examples thereof, where it is stated that one or more of the carbon atoms of the C 1 8 hydrocarbyl group may optionally be replaced by O, S, C O O, C O NR c or NR C, the orientation of the ester and amide groups may be in either direction unless indicated to the contrary