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.
A method of treating myasthenia gravis confined to the eyes iby administering, orally, a therapeutically effective dose the nucleotide (cGMP) phosphodiesterase inhibitor Sildenafil either 100 mg. once a day, or 25 mg. four times a day. The object of this oral therapy being the alleviation of myasthenic complications such as diplopia and ptosis.
