These results show reproducibility selleckchem of the assay. The % RSD values found to be less than 2 indicate that the methods were precise for the determination of drugs in formulation [Table 3]. Table 3 Precision Sensitivity The LOD and LOQ for entacapone were found to be 0.21 and 0.62 ��g, respectively, for Method I. For Method II, they were found to be 0.49 and 1.42 ��g, respectively. Repeatability Repeatability was determined by analyzing 6 ��g/mL (Method I) and 20 ��g/mL (Method II) concentrations of entacapone solution for six times and the % amount determined with % RSD<2 for both the methods. Ruggedness The peak area was measured for the same concentration solutions, six times for both methods. The results were in the acceptable range for both the drugs. The results showed that the % RSD was less than 2% [Table 4].

Table 4 Ruggedness CONCLUSION Both the developed methods are economical, simple, accurate, precise and rugged, and can be used for the usual study of entacapone from its pharmaceutical formulations. The methods are developed for quantification of entacapone in tablets. It is also used in routine quality control of the formulations containing entacapone. ACKNOWLEDGMENTS The authors are thankful to R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur, for providing necessary laboratory facilities and also Wockhardt Research Centre, Aurangabad, for providing entacapone as a gift sample. Footnotes Source of Support: Nil Conflict of Interest: None declared.
The renin-angiotensin-aldosterone system has a key function in the pathogenesis of hypertension, making blockade of this system an ideal target for antihypertensive therapy.

All known clinical effects of angiotensin II, including vasoconstriction, aldosterone release, and augmented catecholamine release, are mediated by the AT1-type angiotensin II receptor.[1] Losartan potassium is the first orally active, nonpeptide antagonist of the angiotensin II subtype 1 receptor.[2] Losartan undergoes substantial first-pass metabolism by cytochrome P450 and results in biotransformation of the major active metabolite, losartan acid. Following oral administration, losartan is rapidly absorbed, reaching maximum concentrations 1�C2 h post administration.[3] Losartan and its active metabolite, losartan acid, selectively and specifically block the binding of angiotensin II to the AT1 receptor found in many tissues.

The active metabolite, losartan acid, is 10�C40 times more potent than losartan.[4�C6] Amlodipine, a third-generation dihydropyridine calcium antagonist, is prescribed for the treatment of angina and hypertension. Oral doses of 5 to 10 mg QD are effective in the treatment Drug_discovery of mild to moderate hypertension and stable angina pectoris.[7�C10] Amlodipine is well tolerated and does not appear to cause some of the undesirable effects often associated with other cardiovascular agents.