Abstract: The present invention relates to a method of treating and/or preventing Alzheimer's disease and/or other tauopathies.

Abstract: A radioactively labelled dihydropyridine compound of the formula ##STR1## in which R.sup.1 represents a phenyl radical which is optionally substituted once or twice, identically or differently, by halogen, nitro, trifluoromethyl or difluoromethoxy, or R.sup.1 represents benzoxadiazolyl,R.sup.2 represents a straight-chain or branched alkyl which has up to 8 carbon atoms and which is optionally substituted by cyano, phenyl, halogen, N-benzyl-N-methylamino, N-phenylpiperazino or by alkoxy having up to 4 carbon atoms, andR.sup.3 and R.sup.4 are identical or different and each represents a cyano or represents a straight-chain or branched alkyl which has up to 6 carbon atoms, is optionally interrupted in the chain by one oxygen atom and is optionally substituted by hydroxyl or amino. The compounds are useful in investigating the pharmacokinetics and pharmacodynamics of dihydropyridines, especially for determining metabolism, modes of elimination and organ-specific action.