RESUMO
Hypertension, myocardial infarction, atherosclerosis, arrhythmias and valvular heart disease, coagulopathies and stroke, collectively known as cardiovascular diseases (CVDs), contribute greatly to the mortality, morbidity and economic burden of illness in Canada and in other countries. It has been estimated that over four million Canadians have high blood pressure, a comorbid condition that doubles or triples the risk of CVD. According to the Heart and Stroke Foundation of Canada, CVDs caused 36% of deaths in 2001 and were responsible for 18% of the total hospital costs in Canada. The majority of Canadians exhibit at least one CVD-related risk factor, such as tobacco smoking, physical inactivity, diabetes, obesity, hypertension, a lack of daily fruit and vegetable consumption, and psychosocial factors, making these people more prone to developing a serious CVD-related illness in the future. It is therefore important that CVD-related causes and concerns be addressed. Given the scope and prevalence of CVDs, it is obvious that a population health approach - 'prevention is better than cure' - would be the most appropriate model to adopt to deal with this ubiquitous health problem and to reduce the costs of hospitalization, long-term medication and rehabilitation. The focus of the present review is to evaluate and compare the results of epidemiological, experimental and clinical studies, reporting on the influence of physical activity, dietary intervention, obesity and cigarette smoking on cardiovascular health and the prevention of CVDs. The prophylactic measures must be dealt with collectively because there is overwhelming evidence that the occurrence of CVDs can be reduced by approximately 80% by making lifestyle modifications. The preventive strategies against CVDs must be targeted at a primary health promotion level before some of the important underlying causes of CVD seriously afflict a person or a population at large. Such preventive approaches would help in reducing not only employee absenteeism but also the hospital and drug costs burdening the health care systems of both developed and developing countries.
RESUMO
Recently, drug interactions with grapefruit juice (GFJ) have received considerable attention from basic scientists, physicians, industry and drug regulatory agencies. GFJ has been shown to inhibit cytochrome P-450 3A4 isoenzyme and P-glycoprotein transporters in the intestine and liver. The GFJ-induced inhibitory effects are considered to be responsible for alterations in drug bioavailability, and pharmacokinetic and pharmacodynamic changes when drugs are ingested concurrently with GFJ. However, little or no interaction is observed when GFJ is taken concomitantly with parentally administered drugs. It is well known that risk factors for cardiovascular disease increase with advancing age, while hepatic metabolic activity decreases in elderly individuals. It is, therefore, possible that the combination of GFJ and cardiovascular medications may pose a health risk, especially in elderly patients. A number of studies have shown interactions of GFJ with cardiovascular drugs such as calcium-channel blockers, angiotensin II receptor antagonists, beta-blockers, and statins. Such interactions are likely to change the pharmacokinetics and pharmacodynamics of these drugs, consequently causing undesirable health effects. Therefore, health care professionals and the public need to be advised of the potential risks associated with the concomitant use of GFJ and interacting medications, especially cardiovascular drugs and agents with a narrow therapeutic index. This review focuses on the adverse interactions of GFJ and cardiovascular medications, and the proposed underlying mechanisms of such interactions.
RESUMO
Increased oxidative stress and antioxidant deficit have been suggested to play a major role in adriamycin-induced cardiomyopathy and congestive heart failure due to multiple treatments with adriamycin (doxorubicin). In this study, we investigated the acute effects of a single dose of adriamycin on myocardial antioxidant enzymes in rats. Adriamycin (2.5 mg/kg) was injected (i.p.) and myocardial antioxidant enzyme activities, mRNA abundance and protein levels at 1, 2, 4 and 24 h were examined. While manganese superoxide dismutase (MnSOD), glutathione peroxidase (GSHPx) and catalase (CAT) activities were not significantly changed, copper-zinc superoxide dismutase (CuZnSOD) activity was reduced at all time points and this change correlated with a decrease in its protein content. CuZnSOD mRNA was increased at 1 and 24 h. GSHPx mRNA and protein levels were transiently decreased by 20 and 25% respectively at 2 h. MnSOD mRNA was not significantly changed, but its protein levels were significantly decreased at 1 h. Lipid peroxidation was increased transiently at 1, 2 and 4 h. A transient depression in antioxidant enzyme as well as transient increase in oxidative stress with a single dose of adriamycin may precede more sustained changes seen with the repeated administration of the drug and contribute to the development of cardiomyopathy and heart failure.
