The use of a Petasitesextract (and/or its fraction(s)) (A) for: (1) the production of a specific cyclooxygenase-2 (COX-2) inhibitor; (2) treatment and/or prophylaxis of diseases treatable by specific COX-2 inhibition; and/or (3) production of a spasmolytic and/or analgesic medicament. Independent claims are included for: (1) a Petasitesextract (and/or its fraction(s)) (A') which contains not more than 30 (preferably less than 0.001) wt. % petasine (I) (based on the solvent-free extract or extract fraction); (2) a specific COX-2 inhibitor based on (A) (in (I)-containing, (I)-depleted or (I)-free form); and (3) a composition based on (A) (in (I)-containing, (I)-depleted or (I)-free form), where (A) is a polar or apolar extract or is enriched with a polar and/or apolar extract. ACTIVITY : Analgesic; antiarthritic; osteopathic; antirheumatic; cytostatic; antiulcer; antiinflammatory; thrombolytic; cardiant; vasotropic; antianginal; cerebroprotective; neuroprotective; hypotensive; antimigraine; antiasthmatic; antiallergic; dermatological; nootropic; tuberculostatic; antipsoriatic; gynecological; tranquilizer; hypnotic; antidepressant; Gastrointestinal-Gen.; Cardiovascular-Gen.; Respiratory-Gen.; Uropathic. MECHANISM OF ACTION : COX-2 inhibitor.