RP-HPLC Method for the Determination of Losartan Potassium and Ramipril in Combined Dosage Form

A simple, specific and accurate reverse phase liquid chromatographic method was developed for the simultaneous determination of losartan potassium and ramipril in table dosage forms. A hypersil ODS C18, 4.6×250 mm, 5 μm column in isocratic mode, with mobile phase acetonitrile:methanol:10 mM tetra butyl ammonium hydrogen sulphate in water in the ratio of 30:30:40% v/v/v was used. The flow rate was 1.0 ml/min and effluent was monitored at 210 nm. The retention times of losartan potassium and ramipril were 4.7 and 3.3 min, respectively. The linearity range for losartan potassium and ramipril were in the range of 0.04-100 μg/ml and 0.2-300 μg/ml, respectively. The proposed method was also validated and successfully applied to the estimation of losartan potassium and ramipril in combined tablet formulations.     

RP—HPLC法测定替米沙坦含量及有关物质

目的:采用反相高效液相色谱法测定替米沙坦的含量及有关物质。方法:色谱柱为Alltech公司Alltima C_(18)柱(150 mm×4.6 mm,5 μm),以乙腈-0.01 mol·L~(-1)醋酸铵缓冲液(60:40,用醋酸调节pH=6.0)为流动相,流速1.0 mL·min~(-1),检测波长分别为298 nm(含量测定)与255 nm(有关物质测定)。结果:替米沙坦在50-250μg·mL~(-1)范围内呈良好的线性关系,r=0.9999;最低检出限0.04 ng;日内精密度(RSD<0.5%)与日间精密度(RSD<0.5%)良好。结论:本方法简便、快速,结果准确、可靠。     

Stability-Indicating RP-HPLC Method for Estimation of Miglitol in Bulk and Tablets

A selective and sensitive, stability-indicating reverse phase high performance liquid chromatography method has been first developed and validated for the estimation of miglitol in bulk and tablet dosages form. Samples were separated on a prepacked, Inertsil amino C(18) column (150×4.6 mm i.d.) using a mobile phase comprised of acetonitrile and monobasic sodium phosphate pH 7.5 (80:20, v/v) delivered at 1.5 ml/min flow rate. Detection was performed on a SPD-20A prominence UV/Vis detector at 220 nm. The retention time for miglitol was 13.93±0.0367. The method was validated in terms of linearity, precision, accuracy, ruggedness, and specificity, limit of detection and limit of quantification. The linearity (r(2)) and percentage recoveries of miglitol were 0.9986 and 99.85%. This method is suitable for routine estimation of miglitol in bulk and tablet dosages form.     

Development and Validation of Stability-indicating RP-HPLC Method for Estimation of Pamabrom in Tablets

The present study depicts the development of a validated RP-HPLC method for the determination of the pamabrom in presence of degradation products or other pharmaceutical excipients. Stress study was performed on pamabrom and it was found that it degrade sufficiently in acidic, alkali and oxidative condition but less degradation was found in thermal and photolytic condition. The separation was carried out on Enable G 120 A⁰ (250×4.6 mm, 5 μ) column having particle size 5 μ using methanol: water (75:25 v/v) with pH 4.0 adjusted with ortho phosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280nm. A retention time (R_t) nearly 3.9 min was observed. The calibration curve for pamabrom was linear (r² = 0.9997) from range of 10-60 μg/ml with limit of detection and limit of quantification of 1.41 μg/ml and 4.28 μg/ml, respectively. Analytical validation parameter such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 101.35%. Thus, the developed RP-HPLC method was found to be suitable for the determination of pamabrom in bulk as well as stability samples of tablets containing various excipients.     

A Validated RP-HPLC Method for Simultaneous Estimation of Nebivolol and Hydrochlorothiazide in Tablets

A simple, selective, rapid, precise and economical reverse phase high pressure liquid chromatographic method has been developed for the simultaneous estimation of nebivolol and hydrochlorthiazide from pharmaceutical formulation. Phenomenex Gemini C(18) (25 cm×4.6 mm i.d., 5 μ) column with a mobile phase consisting of acetonitrile: 50mM ammonium acetate (adjusted to pH 3.5 using orthophosphoric acid) (70:30 v/v) at a flow rate of 1.0 ml/min was used. Detection was carried out at 254 nm. Probenecid was used as an internal standard. The retention times of probenecid, nebivolol and hydrochlorthiazide were 13.05, 3.32 and 4.25 min, respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantitation and solution stability. The proposed method can be used for the estimation of these drugs in combined dosage forms.     

Challenges in improving prognosis and therapy: The Ongoing Telmisartan Alone and in Combination with Ramipril Global End point Trial Programme

Hypertension is one of the most important modifiable risk factors for cardiovascular pathology, such as atherosclerosis and cardiac left ventricular hypertrophy, including acute events such as stroke and myocardial infarction (MI). In particular, the risk of ischaemic and haemorrhagic stroke is directly and continuously related to high blood pressure levels. The renin–angiotensin system (RAS) plays an important role in volume homeostasis and blood pressure regulation. It also helps to prevent cell and organ damage from ischaemia during acute volume loss. However, angiotensin-II (A-II) – the main effector peptide of the RAS – also exerts a number of pathological effects, which are mediated by the AT₁ receptor. The Ongoing Telmisartan Alone and in Combination with Ramipril Global End point Trial (ONTARGET) programme consists of two parallel trials where ONTARGET as a large, long-term study compares the efficacy of the angiotensin-receptor antagonist, telmisartan, the renin–angiotensin-converting enzyme (ACE) inhibitor, ramipril and combination therapy with telmisartan plus ramipril for reducing cardiovascular and cerebral risk. Telmisartan, due to its long duration of action, compares favourably with other angiotensin-receptor antagonists. In the Heart Outcomes Prevention Evaluation (HOPE) study, ramipril was shown to reduce the risk for MI and other cardiovascular events in patients at high risk for pathological cardiac events, but without heart failure or a low ejection fraction. The cardiovascular outcomes of high-risk patients using the same criteria as those of the HOPE study will be assessed in both trials. TRANSCEND differs from ONTARGET in that this trial will enrol patients who do not tolerate ACE inhibitors. This parallel study will therefore be able to compare telmisartan and placebo treatment. Both ONTARGET and TRANSCEND trials feature the same primary composite end point: death caused by cardiovascular disease, acute MI, stroke and hospitalisation because of congestive heart failure. The secondary end points will focus on reductions in the development of Type 2 diabetes mellitus, nephropathy, cognitive decrease and dementia as well as atrial fibrillation.     

Development and Validation of an RP-HPLC Method for Quantitative Estimation of Eslicarbazepine Acetate in Bulk Drug and Tablets

A convenient, simple, accurate, precise and reproducible RP-HPLC method was developed and validated for the estimation of eslicarbazepine acetate in bulk drug and tablet dosage form. Objective was achieved under optimised chromatographic conditions on Dionex RP-HPLC system with Dionex C18 column (250×4.6 mm, 5 μm particle size) using mobile phase composed of methanol and ammonium acetate (0.005 M) in the ratio of 70:30 v/v. The separation was achieved using an isocratic elution method with a flow rate of 1.0 ml/ min at room temperature. The effluent was monitored at 230 nm using diode array detector. The retention time of eslicarbazepine acetate is found to be 4.9 min and the standard calibration plot was linear over a concentration range of 10-90 μg/ml with r²=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 μg/ml, respectively. The amount of eslicarbazepine acetate in bulk and tablet dosage form was found to be 99.19 and 97.88%, respectively. The method was validated statistically using the percent relative standard deviation and the values are found to be within the limits. The recovery studies were performed and the percentage recoveries were found to be 98.33± 0.5%.     

高效液相色谱法测定替米沙坦片含量

目的建立替米沙坦片含量测定的HPLC方法。方法采用HypersilC18柱(250mm×4.6mm,5μm),以甲醇:水:三乙胺(80:20:0.15,磷酸调pH至3.0)为流动相,流速为0.95ml·min-1,检测波长为298nm,进样体积:10μL。结果线性范围为5.04～75.6μg·mL-1(r=0.9999,n=6);高、中、低3种不同浓度的平均回收率为99.62%,RSD为0.28%;精密度为0.21%(n=6)。结论本法快速、准确、专属性高,适于替米沙坦片的含量测定。     

Telmisartan prevents cardiovascular events in a broad group of at-risk patients

The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET^?) was a 25,620 patient study program comparing telmisartan with ramipril or the combination thereof in patients at increased cardiovascular risk. Ramipril had previously been proven to prevent cardiovascular events in a similar population within the HOPE-trial. However, ramipril and other ACE inhibitors (ACE-Is) may have limited tolerability that might restrict their use in patients requiring secondary prevention, whereas angiotensin receptor blockers (ARBs) are suggested to be better tolerated. However, no ARB had been compared with the standard treatment, ramipril, in these cardiovascular patients at increased risk. ONTARGET showed that telmisartan was as effective as ramipril in preventing cardiovascular events, but was better tolerated. The combination of ramipril and telmisartan was not superior to either monotherapy. Taken together, ONTARGET demonstrated that telmisartan is as effective as ramipril in a broad cardiovascular increased-risk population in the middle of the cardiovascular continuum. In these patients who are intolerant to ACE-Is or who do not achieve blood pressure control, the ARB with the best evidence for secondary prevention is telmisartan according to the results of the ONTARGET trial.     

Telmisartan, ramipril and their combination improve endothelial function in different tissues in a murine model of cholesterol-induced atherosclerosis

BACKGROUND AND PURPOSE

Erectile dysfunction correlates with cardiovascular disease and its common risk factors due to the development of endothelial dysfunction. Positive effects on endothelial and erectile function have been described for substances inhibiting the renin-angiotensin-system. Here, we investigated in an atherosclerosis model, whether telmisartan (angiotensin receptor blocker) and ramipril (angiotensin converting enzyme inhibitor) are equivalent or the combination of both is superior in improving endothelial function in the aorta and the corpus cavernosum and in reducing atherosclerosis.

EXPERIMENTAL APPROACH

Wild-type (WT, C57/B6) and apolipoprotein-E-deficient (ApoE^−/−) mice were treated with a cholesterol-rich diet for 8 weeks. ApoE^−/− mice were supplemented with either telmisartan (20 mg·kg⁻¹·day⁻¹), ramipril (2.5 mg·kg⁻¹·day⁻¹) or the combination thereof.

KEY RESULTS

Systolic blood pressure significantly decreased in treatment groups (P < 0.001), with significantly smaller reduction under ramipril monotherapy (P < 0.05). Endothelial function (assessed by pharmacological stimulation of aortic rings and corpus cavernosum in organ bath chambers) was impaired in ApoE^−/− mice compared to WT animals, which was improved by all three treatments to a comparable extent (P < 0.05). Atherosclerotic lesion size in the ascending aorta and aortic sinus (P < 0.001), the amount of lipid peroxides in cavernosal and aortic tissue (P < 0.05) and free radical load (dihydroethidium-stain) (P < 0.05) were enhanced in untreated ApoE^−/− mice in comparison to WT animals and were significantly reduced by either treatment. In penile tissue, expression of eNOS could be restored by renin-angiotensin-aldosterone system blockade.

CONCLUSIONS AND IMPLICATIONS

Telmisartan and ramipril significantly improved endothelial function of aortic and cavernosal tissues in ApoE^−/− via reduction of oxidative stress. Combination of both agents does not enhance beneficial effects significantly.     

RP-HPLC Estimation of Imipramine Hydrochloride and Diazepam in Tablets

A simple and rapid reversed phase-high performance liquid chromatographic method was developed for simultaneous determination of imipramine hydrochloride and diazepam in pharmaceutical formulations. The elution was done in isocratic mode utilizing a mobile phase consisting of methanol:water:0.1M sodium acetate (30:50:20 v/v/v) on Chromosil C18 column with a flow rate of 1.0 ml/min and with detection at 243 nm. The measured retention time was 3.33±0.02 min for imipramine hydrochloride and 4.64±0.02 min for diazepam. Linearity was measured in the range 25-150 μg/ml for imipramine hydrochloride (r²=0.999) and in the range 5-30 μg/ml for diazepam (r²=0.9994), respectively. The limits of detection and quantitation were 0.03 and 0.1 μg/ml for imipramine hydrochloride and 0.02 and 0.07 μg/ml for diazepam. Satisfactory validation was also obtained from recovery (100.95-101.52% for imipramine hydrochloride and 99.47-100.33% for diazepam) studies, intraday and interday precision (<2%) and robustness results. The reported method was the first study of these drugs in combination and could be employed for routine quantitative determination of imipramine hydrochloride and diazepam in tablets.     

Simultaneous RP-HPLC Estimation of Cefpodoxime Proxetil and Clavulanic Acid in Tablets

A new, simple, precise, rapid and accurate RP-HPLC method has been developed for the simultaneous estimation of cefpodoxime proxetil and clavulanic acid from pharmaceutical dosage forms. The method was carried out on a Zorbax Eclipse XDB 5 μ C 18 (150×4.6 mm) column with a mobile phase consisting of acetonitrile:50 mM potassium dihydrogen phosphate buffer (pH 3.0, 70:30 v/v) at a flow rate of 1.0 ml/min. Detection was carried out at 228 nm. Aspirin was used as an internal standard. The retention time of clavulanic acid, cefpodoxime proxetil and aspirin was 4.43, 6.44 and 5.6 min, respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantification and solution stability. The proposed method can be used for the estimation of these drugs in combined dosage forms.     

RP-HPLC Method for Simultaneous Estimation of Nitazoxanide and Ofloxacin in Tablets

A reverse phase high performance liquid chromatography method was developed for simultaneous estimation of nitazoxanide and ofloxacin in tablet formulation. The separation and quantification was achieved by Hiq Sil C₁₈V Size 4.6 mm Ø ^*250 mm column in isocratic mode, with mobile phase consisting of acetonitrile-methanol-0.4 M citric acid, (60:30:10, v/v/v). Citric acid used to stabilize nitazoxanide and ofloxacin in mobile phase. The mobile phase was pumped at a rate of 0.6 ml/min and the detection was carried out at 304 nm. The retention time of ofloxacin and nitazoxanide was found to be 3.122 and 5.902 min, respectively. The method was validated for linearity, accuracy, and precision. Linearity for ofloxacin and nitazoxanide were in the range 2-36 μg/ml and 5-90 μg/ml, respectively. The developed method was found to be accurate, precise and selective for simultaneous estimation of ofloxacin and nitazoxanide in tablets.     

RP-HPLC Estimation of Risperidone in Tablet Dosage Forms

A simple, specific, accurate, and precise reverse phase liquid chromatographic method was developed and validated for the estimation of risperidone in tablet dosage forms. A Phenomenex Gemini C-18, 5 μm column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing methanol: acetonitrile: 50 mM potassium dihydrogen orthophosphate (80:10:10 v/v) was used. The flow rate was 1.3 ml/min and effluents were monitored at 234 nm. Clozapine was used as an internal standard. The retention time of risperidone and clozapine were 2.5 min and 3.3 min, respectively. The method was validated for linearity, accuracy, precision, specificity, limit of quantification, limit of detection, robustness and stability. The limit of detection and limit of quantification for estimation of risperidone was found to be 500 ng/ml and 990 ng/ml, respectively. Recovery of risperidone was found to be in the range of 99.02-101.68%. Proposed method was successfully applied for the quantitative determination of risperidone in tablet formulations.     

反相高效液相色谱法测定替米沙坦片的含量

建立了反相高效液相色谱法测定替米沙坦片的含量.采用Shim-pack C18柱,甲醇-水(含2.5% pH5.8磷酸盐缓冲液)(80∶20)为流动相,检测波长298nm,柱温35℃,流速1.0ml·min-1,以外标法计算替米沙坦片的含量.替米沙坦线性范围为5.0～50μg·ml-1,r=0.9999,平均回收率101.7%,RSD为1.2%(n=5).结果表明本方法简便、专属性强,辅料不干扰主药测定,可用于替米沙坦片的质量控制.     

复方替米沙坦胶囊中替米沙坦和氢氯噻嗪的HPLC测定

建立了HPLC法同时测定复方替米沙坦胶囊中替米沙坦和氢氯噻嗪的含量.采用Hypersil-BDS C18色谱柱,以氢氧化四丁铵磷酸盐缓冲液(pH 2.26)-乙腈(78:22)为流动相,检测波长230nm,柱温30C.替米沙坦在5～200μg/ml(r=0.9999)、氢氯噻嗪在1.6～64μg/ml(r=0.9998)浓度范围内线性关系良好.回收率分别为98.8%～99.8%和99.6%～99.9%.检测限分别为2.5和3.9ng.     

RP-HPLC法测定柴黄片中黄芩苷含量

用反相高效液相色谱法测定柴黄片中黄芩苷的含量.色谱柱为Kromasil-C18,流动相为甲醇-水-磷酸-三乙胺(60:40:0.2:2滴),紫外检测波长为280nm,流速为1.0ml·min-1.黄芩苷对照品在0.0252～1.008μg·ml-1范围内线性关系良好,r=0.9996.平均加样回收率99.6%,RSD为1.4%.方法可行,结果可靠,重现性好.     

RP-HPLC法测定肺安片中盐酸麻黄碱含量

目的:建立测定肺安片中盐酸麻黄碱含量的方法。方法:选用RP-HPLC法对制剂中的盐酸麻黄碱进行含量测定,采用AllsphereODS色谱柱(4.6mm×250mm,2.5μm);流动相:乙腈-水(含0.1%磷酸和0.1%三乙胺)(5∶95);柱温:室温;检测波长:207nm。结果:盐酸麻黄碱对照品在0.5920～2.9600μg范围内线性关系良好,加样回收平均回收率为98.96%。结论:本法对肺安片君药麻黄中活性药理成分盐酸麻黄碱的含量测定准确、操作简单、重复性良好,可有效地控制处方的质量。     

RP-HPLC法测定复方芦荟片中芦荟苷的含量

目的建立测定复方芦荟片中芦荟苷含量的方法。方法采用C18柱,乙腈-1g.L-1磷酸溶液(50∶50)为流动相,检测波长为355nm。结果芦荟苷在0.04708~2.354μg范围内线性关系良好,相关系数为1.0000,回收率为101.2%,RSD为1.3%(n=9)。结论方法操作简便、准确、灵敏度高,适用于复方芦荟片中芦荟苷的含量测定。     

Development and Validation of RP-HPLC Method for the Estimation of Ivabradine Hydrochloride in Tablets

A simple, sensitive, precise and robust reverse-phase high-performance liquid chromatographic method for analysis of ivabradine hydrochloride in pharmaceutical formulations was developed and validated as per ICH guidelines. The separation was performed on SS Wakosil C18AR, 250×4.6 mm, 5 μm column with methanol:25 mM phosphate buffer (60:40 v/v), adjusted to pH 6.5 with orthophosphoric acid, added drop wise, as mobile phase. A well defined chromatographic peak of Ivabradine hydrochloride was exhibited with a retention time of 6.55±0.05 min and tailing factor of 1.14 at the flow rate of 0.8 ml/min and at ambient temperature, when monitored at 285 nm. The linear regression analysis data for calibration plots showed good linear relationship with R=0.9998 in the concentration range of 30-210 μg/ml. The method was validated for precision, recovery and robustness. Intra and Inter-day precision (% relative standard deviation) were always less than 2%. The method showed the mean % recovery of 99.00 and 98.55 % for Ivabrad and Inapure tablets, respectively. The proposed method has been successfully applied to the commercial tablets without any interference of excipients.