JPH0310628B

New 2-piperazino- or 2-homopiperazino-pyrimido (5,4-d) pyrimidine derivs. are cpds. of formula (I) and their physiologically tolerable addition salts with organic and inorganic acids (where R1 is 1-3C alkoxy or alkylmercapto (opt. substd. by OH, (1-3C alkoxy) carbonyl, phenyl, (1-3C alkylmercapto)phenyl or di(1-3C alkyl)amino), mercapto (opt. substd. by 4-8C alkyl or 5-7C cycloalkyl), phenylmercapto or benzylmercapto (opt. mono- or disubstd. by OH, 1-3C alkyl, 1-3C alkoxy, CF3, amino or halogen) or indanylthio; R2 is morpholino, thiomorpholino, 1-oxide -thiomorpholino or 1,1-dioxido-thiomorpholino opt. substd. by 1 or 2 methyl groups; R3 is H, phenyl, 1-5C alkyl (opt. substd. by OH or phenyl), 1-4C alkanoyl (opt. substd. by OMe, acetyl or carboxy), acetoxybenzoyl, pyridinoyl, furanoyl or thenoyl; and n is 2 or 3). (I) are inhibitors of phosphodiesterase and of the aggregation of cancer cells circulating in the bloodstream.