compounds for use in the treatment or prophylaxis of pain , including acute and chronic pain , represented by general formula i : in which : the dotted line represents a single or a double bond ; and r 5 and r 5 ′ are independently — h , — oh or — or 6 , where r 6 is a linear or branched c 1 - c 4 alkyl ; x is — ch 2 o —; z is — ch 2 ch 2 o —, — chch 2 o — or — ch 2 cho —; m is 1 ; and n is an integer of 1 - 5 . the compounds of the invention are also effective for reducing inflammation and may be used alone or in combination with other analgesics .