摘要 |
A compound of formula (I): wherein X represents O or S; R<SUB>1 </SUB>represents C<SUB>1-6 </SUB>alkyl, C<SUB>3-8 </SUB>cycloalkyl, C<SUB>3-8 </SUB>cycloalkylmethyl or C<SUB>3-8 </SUB>cycloalkenyl any of which optionally may be substituted by one or more methyl groups or halogen atoms or R<SUB>1 </SUB>represents aryl, substituted aryl, heteroaryl or substituted heteroaryl; R<SUB>2 </SUB>represents hydrogen, methyl, which may be in either the alpha or beta configuration, or methylene; R<SUB>3 </SUB>and R<SUB>4 </SUB>are the same or different and each independently represents hydrogen, halogen or a methyl group; and <img id="custom-character-00001" he="3.89mm" wi="6.01mm" file="US20080070880A1-20080320-P00900.TIF" img-content="character" img-format="tif"/> represents a single or a double bond; or a physiologically acceptable salt or solvate thereof, and pharmaceutical formulations and methods of use thereof.
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