[Pharmacological profiles and clinical effects of olmesartan medoxomil, a novel angiotensin II receptor blocker]

Method Validation for Simultaneous Quantification of Olmesartan and Hydrochlorothiazide in Human Plasma Using LC-MS/MS and Its Application Through Bioequivalence Study in Healthy Volunteers

A new, simple, sensitive, selective, rapid, and high-throughput liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for simultaneous quantification of Olmesartan and hydrochlorothiazide in human plasma. Simple liquid–liquid extraction procedure was applied for plasma sample pretreatment using a mixture of diethyl ether and dichloromethane, as an extraction solution. Analytes were separated on UNISOL C18 150*4.6 mm, 5 µm column using methanol, and 2 mM ammonium acetate pH 5.5 (80:20, v/v) as a mobile phase and detected by electrospray ionization in the multiple reaction monitoring (MRM) mode. The mass transition ion pairs were followed in negative ion mode as m/z 445.20 → 148.90 for Olmesartan; m/z 451.40 → 154.30 for Olmesartan D₆ and m/z 295.80 → 205.10 for hydrochlorothiazide; m/z 298.90 → 206.30 for hydrochlorothiazide ¹³C D₂. The method showed excellent linearity (r² > 0.99) over the concentration range of 5.002–2,599.934 ng/ml for Olmesartan and from 3.005 to 499.994 ng/ml for hydrochlorothiazide. Precision (% CV) and accuracy (% bias) for Olmesartan were found in the range of 3.07–9.02% and −5.00–0.00%, respectively. Precision (% CV) and accuracy (% bias) for hydrochlorothiazide were found in the range of 3.32–8.21% and 1.99–3.80%, respectively. This as developed novel and high-throughput liquid–liquid extraction bioanalytical method has substantial innovative value with the benefits of cost effectiveness, good extraction efficiency, shorter analysis run time, low organic solvent consumption, and simpler procedure over the previously reported solid-phase extraction method. The application of this method in pharmacokinetic studies was further demonstrated successfully through a bioequivalence study conducted on healthy human subjects, following oral administration of combined formulation of Olmesartan medoxomil and hydrochlorothiazide in fixed-dose tablet.

Emerging drugs for diabetic nephropathy

There is an increasing number of patients with diabetes mellitus in many countries. Diabetic kidney disease, one of its microvascular complications, is also increasing markedly and has become a major cause of end stage renal disease worldwide. Intervention for preventing and delaying the development and progression of diabetic kidney disease is not only a medical concern, but also a social issue. Despite extensive efforts, however, medical interventions thus far are not effective enough to prevent the progression of the disease and the development of end stage renal disease. This justifies attempts to develop novel therapeutic approaches for diabetic nephropathy. Recent insights on its pathogenesis and progression have suggested new targets for the specific treatment of this disease. They include aldosterone, aldose reductase, arachidonic acid metabolites, growth factors, advanced glycosylation end-products, peroxisome proliferator-activated receptors and endothelin. Several other biochemical mediators have been targeted in experimental animal models with the goal to prevent diabetic nephropathy progression, but translation to clinics of these experimental achievements are still limited or lacking.

Angiotensin II antagonists--therapeutic benefits spanning the cardiovascular disease continuum from hypertension to heart failure and diabetic nephropathy

BACKGROUND

The cardiovascular benefits of angiotensin II antagonists (AIIAs) have been evaluated not only in terms of their ability to lower blood pressure but also on their ability to prevent strokes, cardiac events, and target organ damage. This review summarizes the body of evidence-based data demonstrating the efficacy of AIIAs across the spectrum of cardiovascular disease.

METHODS

A PubMed/MEDLINE search of English-language articles (1990 to September 2005) was used to identify articles describing clinical studies, particularly outcome trials, or mechanisms of therapeutic action pertinent to the therapy of cardiovascular disease or nephropathy.

FINDINGS

The antihypertensive efficacy of AIIAs is apparent across a wide spectrum of hypertensive patients, including black and Asian patients and patients with isolated systolic hypertension. More importantly, large outcome-based studies have demonstrated the efficacy of AIIAs across the continuum of cardiovascular disease, including hypertension, heart failure, post-myocardial infarction, and diabetic nephropathy. The Losartan Intervention For Endpoint reduction in hypertension study (LIFE), Reduction of Endpoints in Non-insulin-dependent Diabetes Mellitus with the AII Antagonist Losartan (RENAAL), and the Irbesartan Type 2 Diabetic Nephropathy Trial (IDNT) indicate that AIIAs confer cardiovascular and renal protective effects beyond their ability to lower blood pressure. These bloodpressure independent protective benefits of AIIAs may arise not only by blocking the deleterious effects of AII mediated via the AT1-receptor but may also be due to beneficial molecule-specific effects. As a class, AIIAs are well tolerated with an overall adverse event profile generally comparable to placebo and superior to that typically seen with calcium channel blockers, ACE inhibitors, diuretics, and beta-blockers.

CONCLUSIONS

By utilizing the body of clinical trial evidence as a guide to rational prescribing of AIIAs, practitioners can expect to deliver clinical benefits to their patients in terms of survival, prognosis, and quality of life.