Pharmacologic profiles of KRH-594, a novel nonpeptide angiotensin II-receptor antagonist.
We studied pharmacologic profiles of KRH-594, dipotassium (Z)-2-[[5-ethyl-3-[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl-1,3,4 -thiadiazolin-2-ylidene]aminocarbonyl]-1-cyclopentenecarb oxylate, a novel angiotensin II (AII)-receptor antagonist. KRH-594 potently displaced specific binding of [125I]-AII from AT1 receptor with a Ki of 0.39 nM in rat liver membranes, but not from AT2 receptor in bovine cerebellar membranes (Ki > 10 microM). KRH-594 exhibited no affinity for 21 other receptors and two enzymes [50% inhibitory concentration (IC50) > 10 microM], demonstrating its high specificity toward AT1 receptors. In isolated rabbit aorta, KRH-594 caused nonparallel shifts to the right of the dose-response curve to AII and decreased the maximal response with a pK(B) of 10.4. We evaluated the in vivo efficacy and the duration of action in freely moving rats under nonfasting conditions. In normotensive rats, orally administered KRH-594 inhibited AII-induced pressor responses with a 50% inhibitory dose (ID50) of 0.39 mg/kg. In spontaneously hypertensive rats (SHRs), both KRH-594 (1 mg/kg p.o.) and losartan (10 mg/kg p.o.) exerted similar blood pressure-reducing effects, and their effects were still significant at 24 h after drug administration. We concluded that KRH-594 is a specific and efficacious AT1 antagonist that may find its use in the treatment of human hypertension.
Tamura
K
K
Institute for Medical Research, Wakunaga Pharmaceutical Co., Ltd., Hiroshima, Japan.
Okuhira
M
M
Amano
H
H
Inokuma
K
K
Hirata
T
T
Mikoshiba
I
I
Hashimoto
K
K
D000804:Angiotensin II / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001667:Binding, Competitive; D001794:Blood Pressure / Q000187:drug effects; D002417:Cattle; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006973:Hypertension / Q000188:drug therapy*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D019808:Losartan / Q000494:pharmacology; D008297:Male; D011817:Rabbits; D011869:Radioligand Assay; D051381:Rats; D011918:Rats, Inbred SHR; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism; D013777:Tetrazoles / Q000494:pharmacology*; D013830:Thiadiazoles / Q000494:pharmacology*
D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; C108799:KRH 594; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D013830:Thiadiazoles; D000804:Angiotensin II; D019808:Losartan