Substituted piperidino-dihydrothienopyrimidine compounds (I) and their salts, are new. Substituted piperidino-dihydrothienopyrimidine compounds of formula (I) and their salts, are new. Either R 1> : H or 1-6C alkyl and R 2> : H, 1-10C alkyl or 2-6C alkenyl or NR 1>R 2> : heterocyclic four to seven membered ring either R 3> : e.g. 6-10C-aryl and R 4> : e.g. H, CN, OH or CF 3 or R 3>R 4> : a mono- or bicyclic, unsaturated or or partially saturated heterocycle and X : SO or SO 2. Full Definitions are given in the DEFINITIONS (Full Definitions) Field. [Image] ACTIVITY : Respiratory-Gen. Gastrointestinal-Gen. Antiinflammatory Ophthalmological Dermatological Cytostatic CNS-Gen. Antiasthmatic Antiulcer Gastrointestinal-Gen. Antidepressant Neuroleptic Tranquilizer Neuroprotective Nootropic Antiparkinsonian Analgesic Vulnerary Cerebroprotective. MECHANISM OF ACTION : Phosphodiesterase-4 inhibitor. The ability of (I) to inhibit phosphodiesterase-4 was tested by using scintillation proximity assays (GE healthcare, number TRKQ7090). The result showed that (R)-2-{2-[4-(4-chloro-phenyl)-piperidin-1-yl]-5-oxo-6,7-dihydro-5H-5-thieno[3,2-d]pyrimidin-4-ylamino}-3-methyl-butan-1-ol (I) at a concentration of 1 mu m exhibited a percentage inhibition of 93.