quinta-feira, 8 de novembro de 2007

Uma verdadeira "mudança de paradigma" no controle da hipertensão.

A proposta de uma "vacina" para hipertensão existe há mais de duas décadas. Houve somente insucessos. Agora, na reunião da American Heart Association foram divulgados resultados auspiciosos sobre a administração intramuscular de medicamento que mantém a pressão arterial controlada por quatro meses. Se não houver sucesso nas novas fases de experimentação, haverá mudança radical no panorama do controle de hipertensão em todo o mundo. Vamos torcer.
Hypertension vaccine safe, well-tolerated in phase 2a study November 6, 2007From Medscape Medical News—a professional news service of WebMD Orlando, FL - Results of a phase 2 study suggest that an investigational vaccine against angiotensin II was safe and well tolerated in patients with mild to moderate hypertension. The vaccine produced a long-lived antibody response with a half-life of about four months. "Treatment with the high dose produced a significant reduction of daytime ambulatory blood pressure and a marked reduction in the early morning hours, when most adverse cardiovascular events occur," study author Dr Jürg Nussberger (Centre Hospitalier Université Vaudois, Lausanne, Switzerland) told attendees here at the American Heart Association 2007 Scientific Sessions. "Future studies will apply state-of-the-art formulations and treatment regimens to explore the full potential of this approach," he said. Good control of hypertension has been undermined by problems of patient compliance with antihypertensive medications. Although many effective drugs are available, only about 25% of patients are optimally controlled, Nussberger said. "This has probably something to do with the fact that these drugs have to be taken daily and lifelong." However, many of these drugs have a half-life of less than 24 hours, so if patients take them in the morning, the medications are at a trough in the early-morning hours, he said, just as the normal rise in BP takes place and when most cardiovascular events occur. "With a vaccine against angiotensin II, where there is a long-lasting effect with antibodies, you may not have this problem of peak-trough, and the patient has to come to the doctor maybe only two or three times a year," Nussberger said. Previous work by Morris J. Brown and colleagues at the University of Cambridge, United Kingdom, had tested a vaccine against angiotensin I and shown some reduction of aldosterone, but no BP-lowering effect. The current study explored the safety and tolerability of CYT006-AngQb, a viruslike particle-based conjugate vaccine that targets angiotensin II in a placebo-controlled phase 2a sequential two-dose comparison trial. The study enrolled 72 patients with mild to moderate hypertension, defined as a systolic pressure of 140 to 179 mm Hg and a diastolic pressure of 90 to 109 mm Hg; five patients dropped out for reasons unrelated to the study, he noted. The study was done over four months; patients were given 100 µg or 300 µg of the antigen or placebo at time zero, then at one month and three months, after which they were followed for eight months for safety. End points were safety and tolerability, with an "exploratory" look at efficacy with ambulatory BP measurements and plasma renin concentrations. Adverse events occurred in all patients in both groups, a finding that was not unexpected, since even placebo patients received an injection of aluminum hydroxide emulsion and so reported pain, erythema, or edema at the injection site. Headache was also more frequent in the vaccination group, but all of these effects occurred over the first one or two days and were reversible

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