A method for treating Tourette's Syndrome and other central nervous system disorders. An effective amount of sildenafil or a pharmaceutically acceptable salt thereof is orally administered to patients suffering from Tourette's Syndrome and other central nervous system disorders to diminish the symptoms associated with such a disorder.
Sildenafil, a known pharmaceutical chemical useful in treatment of male sexual dysfunction, is prepared by processes in which the final chemical intermediate is of significantly lower basicity than sildenafil itself, so that sildenafil can be extracted in substantially pure form from the organic reaction mixture in which it is made by adding an aqueous medium of appropriately chosen acidic pH and causing phase shift of the sildenafil to occur selectively into the aqueous phase.
The present invention relates to new 1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one compounds of formula (I), or a pharmaceutically acceptable salt or a stereoisomer thereof, useful for treatment of impotence diseases: ##STR1## wherein R.sub.1 and R.sub.2 may be the same or different and independently be C.sub.1-6 alkyl. The present invention also provides a method of preparing the compounds of formula (I).
There is provided compounds of formula IA and of formula IB, ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and A have meanings given in the description, which are useful in the curative and prophylactic treatment of a medical condition for which inhibition of a cyclic guanosine 3',5'-monophosphate phosphodiesterase (e.g. cGMP PDE5) is desired.
