• 약학회지
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• 제55권3호
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• pp.240-246
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• 2011

The present study was to investigate the effect of glipizide on the pharmacokinetics of losartan in rats. Losartan was administered intravenously (3 mg/kg) and orally (9 mg/kg) in the presence and absence of glipizide (0.3 and 1 mg/kg) to rats. The pharmacokinetic parameters of losartan were significantly altered by the presence of glipizide compared with the control group (given losartan alone). Presence of glipizide significantly (p<0.05, 0.3 mg/kg) increased the area under the plasma concentration-time curve (AUC) of losartan by 48.2% and peak plasma concentration ($C_{max}$) of losartan by 47.4%. Consequently, the absolute bioavailability (AB%) of losartan in the presence of glipizide was 38%, which was enhanced significantly (p<0.05) compared to that in the oral control group (25%). The relative bioavailability (RB%) of losartan increased by 1.18- to 1.48-fold in the presence of glipizide. However, there was no significant change in the peak plasma concentration ($T_{max}$) and terminal half-life ($T_{1/2}$) of losartan in the presence of glipizide. In contrast, glipizide did not affect the pharmacokinetics of intravenous losartan. In conclusion, the presence of glipizide significantly enhanced the oral bioavailability of losartan, implying that glipizide might be mainly to inhibit the cytochrome P450 (CYP) 2C9-mediated metabolism, resulting in reducing gastrointestinal and/or hepatic first-pass metabilism of losartan rather than in reducing P-glycoprotein-mediated efflux and renal elimination of losartan. Concurrent use of glipizide with losartan should require close monitoring for potential drug interactions.

• 약학회지
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• 제53권5호
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• pp.259-264
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• 2009

The present study was to investigate the effect of naringin, a flavonoid, on the pharmacokinetics of losartan in rats. Pharmacokinetic parameters of losartan in rats were determined after an oral administration of losartan (9 mg/kg) in the presence or absence of naringin (0.5, 2.5 and 10 mg/kg). The pharmacokinetic parameters of losartan were significantly altered by the presence of naringin compared with the control group (given losartan alone). Presence of naringin significantly (p<0.05, 2.5 mg/kg; p<0.01, 10 mg/kg) increased the area under the plasma concentration?time curve (AUC) of losartan by 43.7~63.0% and peak plasma concentration ($C_{max}$) of losartan by 31.7~45.5%. Consequently, the absolute bioavailability (AB) of losartan in the presence of naringin was 43.8~62.9%, which was enhanced significantly (p<0.05, p<0.01) compared to that in the oral control group (22.4%). The relative bioavailability (R.B.) of losartan increased by 1.44- to 1.63-fold in the presence of naringin. However, there was no significant change in the peak plasma concentration ($T_{max}$) and terminal half-life ($t_{1/2}$) of losartan in the presence of naringin. In conclusion, the presence of naringin significantly enhanced the oral bioavailability of losartan, implying that presence of naringin might be mainly effective to inhibit the cytochrome P450 (CYP)3A-mediated metabolism, resulting in reducing gastrointestinal and hepatic first-pass metabilism and Pglycoprotein (P-gp)-mediated efflux of losartan in small intestine. Concurrent use of naringin or naringin-containing dietary supplement with losartan should require close monitoring for potential drug interactions.

• The Korean Journal of Physiology and Pharmacology
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• 제14권5호
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• pp.299-304
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• 2010

Losartan is a selective angiotensin II (Ang II) type 1 ($AT_1$) receptor antagonist which inhibits vascular smooth muscle cells (VSMCs) contraction and proliferation. We hypothesized that losartan may prevent cell proliferation by activating AMP-activated protein kinase (AMPK) in VSMCs. VSMCs were treated with various concentrations of losartan. AMPK activation was measured by Western blot analysis and cell proliferation was measured by MTT assay and flowcytometry. Losartan dose- and time-dependently increased the phosphorylation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC) in VSMCs. Losartan also significantly decreased the Ang II- or 15% FBS-induced VSMC proliferation by inhibiting the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. Compound C, a specific inhibitor of AMPK, or AMPK siRNA blocked the losartan-induced inhibition of cell proliferation and the $G_0/G_1$ cell cycle arrest. These data suggest that losartan-induced AMPK activation might attenuate Ang II-induced VSMC proliferation through the inhibition of cell cycle progression.

• The Korean Journal of Physiology and Pharmacology
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• 제13권4호
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• pp.327-335
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• 2009

The aim of this study was to determine whether losartan, an angiotensin II (Ang II) type 1 ($AT_1$) receptor could influence the CA release from the isolated perfused model of the rat adrenal medulla. Losartan (5${\sim}$50 ${\mu}$M) perfused into an adrenal vein for 90 min produced dose- and time-dependent inhibition of the CA secretory responses evoked by ACh (5.32 mM), high $K^+$ (56 mM, a direct membrane depolarizer), DMPP (100 ${\mu}$M) and McN-A-343 (100 ${\mu}$M). Losartan failed to affect basal CA output. Furthermore, in adrenal glands loaded with losartan (15 ${\mu}$M) for 90 min, the CA secretory responses evoked by Bay-K-8644 (10 ${\mu}$M, an activator of L-type $Ca^{2+}$ channels), cyclopiazonic acid (10 ${\mu}$M, an inhibitor of cytoplasmic $Ca^{2+}$ -ATPase), veratridine (100 ${\mu}$M, an activator of $Na^+$ channels), and Ang II (100 nM) were markedly inhibited. However, at high concentrations (150${\sim}$300 ${\mu}$M), losartan rather enhanced the CA secretion evoked by ACh. Collectively, these experimental results suggest that losartan at low concentrations inhibits the CA secretion evoked by cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by membrane depolarization from the rat adrenal medulla, but at high concentration it rather inhibits ACh-evoked CA secretion. It seems that losartan has a dual action, acting as both agonist and antagonist to nicotinic receptors of the rat adrenal medulla, which might be dependent on the concentration. It is also thought that this inhibitory effect of losartan may be mediated by blocking the influx of both $Na^+$ and $Ca^{2+}$ into the rat adrenomedullary chromaffin cells as well as by inhibiting the $Ca^{2+}$ release from the cytoplasmic calcium store, which is thought to be relevant to the $AT_1$ receptor blockade, in addition to its enhancement of the CA release.

• Journal of Chest Surgery
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• 제56권5호
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• pp.295-303
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• 2023

Background: The use of Adriamycin (ADR), also known as doxorubicin, as a chemotherapy agent is limited by its detrimental adverse effects, especially cardiotoxicity. Recent studies have emphasized the crucial role of angiotensin II (Ang-II) in the development of ADR-induced cardiomyopathy. This study aimed to explore the potential cardioprotective effects of losartan in a rat model of ADR-induced cardiomyopathy. Methods: Male Sprague-Dawley rats were randomly divided into 3 groups: a control group (group C), an ADR-treated group (ADR 5 mg/kg/wk for 3 weeks via intraperitoneal injections; group A), and co-treatment of ADR with losartan group (same dose of ADR and losartan; 10 mg/kg/day per oral for 3 weeks; group L). Western blot analysis was conducted to demonstrate changes in brain natriuretic peptide, collagen 1, tumor necrosis factor (TNF)-α, interleukin-6, matrix metalloproteinase (MMP)-2, B-cell leukemia/lymphoma (Bcl)-2, Bcl-2-associated X (Bax), and caspase-3 protein expression levels in left ventricular (LV) tissues from each group. Results: Losartan administration reduced LV hypertrophy, collagen content, and the expression of pro-inflammatory factors TNF-α and MMP-2 in LV tissue. In addition, losartan led to a decrease in the expression of the pro-apoptotic proteins Bax and caspase-3 and an increase in the expression of the anti-apoptotic protein Bcl-2. Moreover, losartan treatment induced a reduction in the apoptotic area compared to group A. Conclusion: In an ADR-induced cardiomyopathy rat model, co-administration of ADR with losartan presented cardioprotective effects by attenuating LV hypertrophy, pro-inflammatory factors, and apoptosis in LV tissue.

• 대한약리학회지
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• 제30권3호
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• pp.337-342
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• 1994

선천성고혈압흰쥐 (SHR)에서 angiotensin converting enzyme inhibitor (ACEI)를 처치하면 내피세포 의존적 이완이 증진된다고 알려져 있다. 본 실험은 angiotensin II가 nitric oxide (NO)와 관련되어 일어나는 적출 대동맥의 이완력에 변화를 주는지 관찰하고자 angiotensin II 작용 억제를 위해 angiotensin II 수용체 차단제인 losartan과 ACEI인 enalapril을 사용하였으며 혈관에서의 NO는 혈관내피세포에서 생성되는 constitutive NO와 주로 혈관 평활근에서 LPS에 생성되는 inducible NO가 있으므로 이들 양자에 대한 angiotensin II의 작용을 검토하였다. 2주간 losartan (30 mg/kg/day)과 enalapril (10 mg/kg/day)을 처치한 경우 acetylcholine $(10^{-9}\;to\;10^{-5}\;M)$과 histamine $(10^{-8}\;to\;10^{-4}\;M)$에 의한 이완 반응이 증가되었으나 90분간 적출 대동맥에 losartan $(10^{-4}\;M)$ 을 노출시킨 경우는 이완 반응에 변화가 없었다. Phenylephrine $(10^{-7}\;M)$ 을 2시간 간격으로 반복 투여하여 수축시킨 경우 LPS $(100\;{\mu}g/ml)$처치에 의해 시간이 지남에 따라 수축력이 감소되었고 대조군에서는 수축력이 감소되지 않았다. LPS 처치에 따른 phenylephrine에 의한 수축력의 감소는 enalapril이나 losartan을 2주간 처치한 경우에도 영향을 받지 않았다. 이상의 결과로 미루어 아마도 losartan의 내피세포에 대한 작용은 constitutive NO 생성을 증가시키나 inducible NO 생성에는 영향을 미치지 않을 것으로 여겨진다.

• Clinical and Experimental Pediatrics
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• 제62권3호
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• pp.95-101
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• 2019

Purpose: Increased apoptosis was recently found in the hypertrophied left ventricle of spontaneously hypertensive rats (SHRs). Although the available evidence suggests that apoptosis can be induced in cardiac cells by various insults including pressure overload, cardiac apoptosis appears to result from an exaggerated local production of angiotensin in adult SHRs. Altered expressions of Bcl associated X (Bax), Bcl-2, chemokine receptor (CCR)-2, monocyte chemoattractant protein (MCP)-1, transforming growth factor $(TGF)-{\beta}1$, phosphorylated extracellular signal-regulated kinases (PERK), and connexin 43 proteins, and kallikrein mRNA were investigated to explore the effects of losartan on the SHR model. Methods: Twelve-week-old male rats were grouped as follows: control (C), SHR (hypertension: H), and losartan (L; SHRs were treated with losartan [10 mg/kg/day] for 5 weeks). Western blot and reverse transcription polymerase chain reaction assays were performed. Results: Expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, PERK, and connexin 43 proteins, and kallikrein mRNA was significantly increased in the H group compared to that in the C group at weeks 3 and 5. Expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, and connexin 43 proteins and kallikrein mRNA was significantly decreased after losartan treatment at week 5. PERK protein expression was significantly decreased after losartan treatment at weeks 3 and 5. Bcl-2 protein expression was significantly decreased in the H group compared to that in the C group at weeks 3 and 5. Conclusion: Losartan treatment reduced expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, PERK, and connexin 43 proteins, and kallikrein mRNA in SHRs, along with decreased inflammation and apoptosis.

• 대한약침학회지
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• 제26권4호
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• pp.298-306
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• 2023

Objectives: Cucumis sativus L. (C. sativus) is vegetable commonly used for managing blood pressure and often consumed in combination with standard antihypertensive therapy, despite lack of scientific evidence supporting their use. Combination of herbs and standard medication could have positive or negative effects. Therefore, this study aimed to evaluate the antihypertensive activity of C. sativus and the combined effect with losartan in the hypertensive rat model induced by angiotensin II. Angiotensin II is a component of the renin-angiotensin-aldosterone system that, upon binding to its receptor, constricts blood vessels leading to elevation of blood pressure. Methods: In an antihypertensive study, rats received C. sativus orally at doses of 9, 18, 27, and 36 mg/kg (full dose); while in a combination study, animals received losartan 2.25 mg/kg combined by either with C. sativus 9 or 18 mg/kg. The standards group received losartan 2.25 mg/kg or 4.5 mg/kg (full dose). Results: Blood pressure was measured using the tail-cuff method. C. sativus significantly attenuated angiotensin II-induced hypertension as observed in groups receiving C. sativus at 9, 18, 27, and 36 mg/kg at 30 minutes after induction showed the average change (Δ) of systolic blood pressure (SBP) and diastolic blood pressure (DBP) with respect to time zero were 28.8/18.3, 24.8/15.8, 22.8/15.5, and 11.5/9.0 mmHg, respectively. Whereas the average change (Δ) of SBP and DBP in the rats receiving the combination of half doses of C. sativus and losartan were 8.8/9.0 mmHg, respectively. These diminished effects were better than a full dose of C. sativus and comparable with a full dose of losartan (6.5/7.8 mmHg). Conclusion: The present findings indicate that C. sativus dose-dependently blocks blood pressure elevation induced by angiotensin II. The combination of half dose of C. sativus and losartan has an additive effect in lowering blood pressure.

• Archives of Pharmacal Research
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• 제19권6호
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• pp.462-468
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• 1996

The present study was undertaken to investigate the effects of age on angiotensin II (AII) response and antagonistic activity of losartan using aortic rings and liver homogenates from rats ranging in age from 0.7 to 20 months. Whether the endothelium was present or not, the maximum contractile response to AII decreased with age. Removal of the endothelium enhanced AII-induced maximum contraction and these endothelial effects seemed to be due to endothelium-derived relaxing factor (EDRF) in all ages. Equilibrium binding studies demonstrated an age-related decrease in maximum binding $(B_{max})$ with little change in binding affinity $(K_d)$. In rat aorta, the extent of losartan-induced parallel shifts $(K_B)$ in AII concentration-response curves was not significantly different between ages. In addition, $IC_{50}$ value of losartan in competition binding was not changed with age in rat liver homogenates. These results suggest that the potency of losartan is not altered with age in rat aorta and liver, although AII-induced contractile response and the maximum AII binding decreased significantly with age.

• Journal of Pharmaceutical Investigation
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• 제36권2호
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• pp.131-136
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• 2006

The purpose of the present study was to evaluate the bioequivalence of two losartan tablets, $Cozaar^{TM}$ tablet (MSD Korea. Co., Ltd., Seoul, Korea, reference drug) and $Losartan^{TM}$ tablet (DaeWon Pharm. Co., Ltd., Korea, test drug), according to the guidelines of Korea Food and Drug Administration (KFDA). Twenty-four healthy male Korean volunteers received two tablets at the losartan kalium dose of 100 mg in a $2\;{\time}\;2$ crossover study. There was a one-week washout period between the doses. Plasma concentrations of losartan were monitored by an LC-MS/MS for over a period of 12 hr after the administration. $AUC_t$ (the area under the plasma concentration-time curve from time zero to 12 hr) was calculated by the linear trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the crossover design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for $Cozaar^{TM}/Losartan^{TM}$ were $log\;0.97{\sim}log\;1.12\;and\;log\;0.93{\sim}log\;1.23$, respectively. These values were within the acceptable bioequivalence intervals of $log\;0.80{\sim}log\;1.25$. Taken together, our study demonstrated the bioequivalence of $Cozaar^{TM}$ and $Losartan^TM$ with respect to the rate and extent of absorption.