Evaluation and improvement of bioavailability of a new angiotensin II receptor antagonist, 2-butyl-1-[2'-(1H-tetrazol-5-yl)biphenyl-4-yl] methyl-1H-benzimidazole-7-carboxylic acid by making prodrug

An angiotensin II receptor antagonist reduces myocardial damage in an animal model of myocarditis

BACKGROUND

Recently, an angiotensin-converting enzyme inhibitor was shown to have a beneficial effect on virus-induced myocardial injury. We investigated the effect of a new angiotensin II type 1 receptor antagonist, (+-)-1-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-([2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl)-1H-benz imi dazole-7- carboxylate (TCV-116), in an animal model of viral myocarditis induced by encephalomyocarditis virus.

METHODS AND RESULTS

Four-week-old DBA/2 mice were inoculated with the encephalomyocarditis virus. TCV-116 (in 5% gum arabic) was given 1 day before (1 or 10 mg/kg) or 2 days after virus inoculation (0.3 or 3 mg/kg). Control mice received the vehicle only. All drugs were administered orally on a daily basis, and the animals were killed on day 14. When treatment was started 1 day before inoculation, the survival of mice receiving 10 mg/kg of TCV-116 improved (17 of 20 [85%] versus 14 of 22 [64%] control mice), but the difference was not significant. Heart weight (106 +/- 24 mg versus 133 +/- 33 mg, P < .05), histological scores for myocardial necrosis (1.1 +/- 0.3 versus 2.3 +/- 1.2, P < .01), cellular infiltration (1.4 +/- 0.7 versus 2.6 +/- 1.3, P < .05), and calcification (1.1 +/- 0.3 versus 2.1 +/- 1.1, P < .01) were significantly decreased in mice given TCV-116 at 3 mg/kg compared with the vehicle control mice. The plasma angiotensin II level was significantly higher in infected mice than in noninfected mice (71.8 +/- 30.2 versus 31.8 +/- 22.5 pg/mL, P < .05). TCV-116 did not inhibit viral replication in the heart.

CONCLUSIONS

This study suggests that angiotensin II plays an important pathophysiological role in viral myocarditis. Treatment with TCV-116, an angiotensin II receptor antagonist, had a cardioprotective effect.

Role of angiotensin II in renal injury of deoxycorticosterone acetate-salt hypertensive rats

To investigate the role of angiotensin II (Ang II) in hypertension-induced tissue injury, we gave TCV-116 (1 mg/kg per day PO), a nonpeptide Ang II type I receptor antagonist, or enalapril (10 mg/kg per day PO) to deoxycorticosterone acetate (DOCA)-salt hypertensive rats for 3 weeks and examined the effects on tissue mRNA levels for transforming growth factor-beta 1 (TGF-beta 1) and extracellular matrix components. Tissue mRNA levels were measured by Northern blot analysis. Renal mRNA levels for TGF-beta 1; types I, III, and IV collagen; and fibronectin in DOCA-salt hypertensive rats were increased by severalfold (P < .01) compared with sham-operated rats. In the aorta of DOCA-salt hypertensive rats, TGF-beta 1 and fibronectin mRNA levels were increased, but types I, III, and IV collagen mRNAs did not increase. In the heart, increased mRNA was found only for fibronectin. Thus, these gene expressions are regulated in a tissue-specific manner. TCV-116 or enalapril did not lower blood pressure in DOCA-salt hypertensive rats. However, the increase in renal mRNAs for TGF-beta 1 and extracellular matrix components in DOCA-salt hypertensive rats was significantly inhibited by treatment with TCV-116 or enalapril, which was associated with a significant decrease in urinary protein and albumin excretions and histological improvement of renal lesions. In contrast, in the aorta and heart these gene expressions were not affected by TCV-116 or enalapril. Thus, local Ang II may contribute to renal injury of DOCA-salt hypertension by stimulating the gene expression of TGF-beta 1 and extracellular matrix components.