Orally active GPIIb/IIIa antagonists: Synthesis and biological activities of masked amidines as prodrugs of 2-[(3S)-4-[(2S)-2-(4-amidinobenzoylamino)-3-(4-methoxyphenyl)propanoyl]-3- (2-methoxy-2-oxoethyl)-2-oxopiperazinyl]acetic acid

Article abstract of DOI:10.1248/cpb.49.268

To improve the in vivo potency of the potent GPIIb/IIIa antagonist 2-[(3S)-4-[(2S)-2-(4-amidinobenzoylamino)-3-(4-methoxyphenyl)propanoyl]-3- (2-methoxy-2-oxoethyl)-2-oxopiperazinyl]lacetic acid (4), the amidino group was converted to an oxadiazole ring, thiadiazole ring of substituted amidoxime group. These groups were expected to be metabolized to an amidino group in vivo. The compounds synthesized were evaluated for their potency to inhibit the ex vivo adenosine 5′-diphosphate (ADP)-induced aggregation of guinea pig platelets. Among the compounds examined, the methoxycarbonyloxyamidine 8a exhibited the most potent ex vivo inhibitory activity with a fast onset and prolonged duration of action after oral administration.