Synergism of amlodipine and candesartan on blood pressure reduction and organ protection in hypertensive rats

Safety and efficacy of candesartan versus valsartan combined with amlodipine on peripheral and central blood pressure

INTRODUCTION

"Amlodipine/valsartan" or "amlodipine/candesartan" combinations represent two effective antihypertensive agents with complementary mechanisms of action. Nevertheless, a study has yet to be done to evaluate the effect of amlodipine/candesartan on central blood pressure and compare it with amlodipine/valsartan combination. To see how "amlodipine plus candesartan combination" reduces peripheral and central blood pressure compared to the most studied combination, "amlodipine plus valsartan".

MATERIAL AND METHODS

Eighty-six patients were randomized in an open-label, prospective study by 1:1 ratio to two groups. Group I (n=42) received the amlodipine and valsartan combination, and group II (n=44) received the amlodipine and candesartan combination. Peripheral and central blood pressure (CBP) was measured at baseline, at 6 and 12 weeks of follow-up.

DISCUSSION

Both treatment groups reduced peripheral systolic, diastolic, and mean blood pressure. There was no significant difference between and within both groups. The amlodipine/candesartan combination showed more reduction in peripheral systolic blood pressure (PSBP) after 12 weeks of treatment (p=<0.001). Both groups decreased CBP without significant differences between groups. The amlodipine/candesartan combination showed additional efficacy in decreasing CSBP after 12 weeks (p=<0.001). The two treatment groups did not exert significant efficacy in lowering heart rate (HR) and augmentation index% (AIx%).

CONCLUSION

To conclude, the amlodipine 10mg/candesartan 16mg combination was non-inferior to the amlodipine 10mg/valsartan 160mg combination in terms of reducing peripheral and CBP over time.

Synergism of amlodipine and telmisartan or candesartan on blood pressure reduction by using SynergyFinder 3.0 and probability sum test in vivo

This study was designed to evaluate the synergism of two couples of antihypertensive drugs (amlodipine + telmisartan and amlodipine + candesartan) on blood pressure reduction in vivo by both SynergyFinder 3.0 and probability sum test. Spontaneously hypertensive rats were treated with intragastric administration of amlodipine (0.5, 1, 2, and 4 mg/kg), telmisartan (4, 8, and 16 mg/kg), candesartan (1, 2, and 4 mg/kg), nine combinations for amlodipine and telmisartan, and nine combinations for amlodipine and candesartan. The control rats were treated by 0.5% carboxymethylcellulose sodium. Blood pressure was recorded continuously up to 6 h after administration. Both SynergyFinder 3.0 and the probability sum test were used to evaluate the synergistic action. The synergisms calculated by SynergyFinder 3.0 are consistent with the probability sum test both in two different combinations. There is an obviously synergistic interaction between amlodipine and telmisartan or candesartan. The combinations of amlodipine and telmisartan (2 + 4 and 1 + 4 mg/kg) and amlodipine and candesartan (0.5 + 4 and 2 + 1 mg/kg) might exert an optimum synergism against hypertension. Compared with the probability sum test, SynergyFinder 3.0 is more stable and reliable to analyze the synergism.

Antihypertensive Effect of a Novel Angiotensin II Receptor Blocker Fluorophenyl Benzimidazole: Contribution of cGMP, Voltage-dependent Calcium Channels, and BKCa Channels to Vasorelaxant Mechanisms

Background: The current study presents the novel angiotensin II receptor blocker fluorophenyl benzimidazole (FPD) as an antihypertensive agent in the SHR model of hypertension. We investigated the role of cGMP, voltage-dependent L-type calcium channels, and BK_Ca channels in the vasorelaxant mechanisms of FPD in the rat superior mesenteric artery.

Methods: The antihypertensive effect of FPD was examined using an invasive technique measuring blood pressure in SHR animals. Using a myograph, tension measurement was completed in the superior mesenteric artery to elucidate the mechanisms of vasorelaxation involving AT1 receptors, the NO/cGMP pathway, L-type calcium channels, and BK_Ca channels. Ion flux (Ca²⁺, K⁺) studies were conducted in aortic smooth muscle cells. Putative targets proteins were determined by in silico docking studies. A safety evaluation of FPD was carried out using Swiss albino mice.

Results: FPD significantly decreased blood pressure in SHR. It relaxed superior mesenteric arteries in a concentration-dependent manner and significantly inhibited angiotensin II-induced contraction. The relaxation response was also mediated by an increase in tissue cGMP levels, inhibition of L-type calcium channels, and the opening of BK_Ca channels. FPD further enhanced efflux of K⁺ and inhibited Bay K8644-stimulated Ca²⁺ influx in aortic smooth muscle cells and docked well in an in silico study with the targets. It was well tolerated in the toxicity study.

Conclusion: The present study reports the antihypertensive activity of novel AT-1 receptor blocker FPD at 50 and 100 mg kg⁻¹ with cGMP, L-type calcium channels, and BK_Ca channels as putative targets of vasorelaxation, and was found safe in oral toxicity.