Piperidine derivatives (I) are new. Piperidine derivatives of formula (I) are new. [Image] R : H, alkali metal or alkaline earth metal； and n : 1-5. An independent claim is also included for 4-(3-cyclopentyloxy-4-difluoromethoxyphenyl)-4-cyanopiperidine (III) and its salts. ACTIVITY : Antiinflammatory； Antidiabetic； Antiallergic； Immunosuppressive； Antiasthmatic； Respiratory-Gen.； Antibacterial； Nephrotropic； Hepatotropic； Gastrointestinal-Gen.； Ophthalmological； Dermatological； Antiulcer； Antirheumatic； Neuroprotective； Osteopathic； Antiarthritic； Anorectic； Eating-Disorders-Gen.； Antidepressant； Antiparkinsonian； Nootropic； Vasotropic； Cytostatic； Anti-HIV. MECHANISM OF ACTION : Phosphodiesterase-Inhibitor-4. In assays using U937 cells 2-(4-(3-cyclopentyloxy-4-difluoromethoxyphenyl)-4-cyanopiperidin-1-yl)acetic acid monohydrate (Ia) had an IC 5 0 value for phosphodiesterase-4 of 42 nmol/L.
