bond or is selected from the group consisting of ch 2 o s and n and z is a alkyl or cycloalkyl radical including from three to ten carbon atoms or an aromatic radical including a hydrocarbyl aromatic radical having from six to ten carbon atoms or a heterocyclic aromatic radical having from four to ten carbon atoms and including a heterocyclic atom selected from the group consisting of nitrogen oxygen and sulfur and pharmaceutically acceptable salts and esters thereof a preferred group of the compounds of the present invention includes compounds that have the following structural formula ii wherein the hatched segment represents an u03b1 bond and the solid triangle represents a u03b2 bond the most preferred group of compounds utilized in the method of the present invention are selected from the group wherein z is phenyl or represented by the formula iv wherein u is selected from the group consisting of o and s a is selected from the group consisting of n u2014 ch and c r 5 is selected from the group consisting of hydrogen halogen lower alkyl having from 1 to 6 carbon atoms and lower alkoxy having from 1 to 6 carbon atoms r 6 and r 7 are selected from the group consisting of hydrogen halogen lower alkyl having from 1 to 6 carbon atoms and lower alkoxy having from 1 to 6 carbon atoms or together with r 6 and r 7 forms a condensed aryl ring preferably r is co 2 r 4 and more preferably r 4 is h or methyl the above compounds of the present invention.