Mild hypertension in the elderly. A comparison of prazosin and enalapril

Oroxylin A reverses hypoxia-induced cisplatin resistance through inhibiting HIF-1α mediated XPC transcription

Hypoxia is a key concern during the treatment of non-small cell lung cancer (NSCLC), and hypoxia-inducible factor 1 alpha (HIF-1α) has been associated with increased tumor resistance to therapeutic modalities such as cisplatin. Compensatory activation of nucleotide excision repair (NER) pathway is the major mechanism that accounts for cisplatin resistance. In the present study, we suggest a novel strategy to improve the treatment of NSCLC and overcome the hypoxia-induced cisplatin resistance by cotreatment with Oroxylin A, one of the main bioactive flavonoids of Scutellariae radix. Based on the preliminary screening, we found that xeroderma pigmentosum group C (XPC), an important DNA damage recognition protein involved in NER, dramatically increased in hypoxic condition and contributed to hypoxia-induced cisplatin resistance. Further data suggested that Oroxylin A significantly reversed the hypoxia-induced cisplatin resistance through directly binding to HIF-1α bHLH-PAS domain and blocking its binding to HRE3 transcription factor binding sites on XPC promoter which is important to hypoxia-induced XPC transcription. Taken together, our findings not only demonstrate a crucial role of XPC dependent NER in hypoxia-induced cisplatin resistance, but also suggest a previously unrecognized tumor suppressive mechanism of Oroxylin A in NSCLC which through sensitization of cisplatin-mediated growth inhibition and apoptosis under hypoxia.

Alpha1-adrenergic blockers: current usage considerations

Alpha1-adrenergic-blocking drugs are effective in reducing blood pressure and do so in a fashion comparable to most other antihypertensive drug classes. These compounds are most effective in patients in the upright position, reducing systolic and diastolic pressures by 8%-10%. Alpha1-adrenergic-blocking drugs incrementally reduce blood pressure when combined with most drug classes and are the only antihypertensive drug class to improve plasma lipid profiles. Alpha1-adrenergic-blocking drugs are also accepted as important elements of the treatment plan for symptomatic benign prostatic hypertrophy. Dose escalation of an alpha1-adrenergic-blocking drug can trigger renal Na+ retention, and the ensuing volume expansion can attenuate its blood pressure-lowering effect. Orthostatic hypotension can occur with these compounds, particularly when a patient is volume-contracted. Dizziness, headache, and drowsiness are common side effects with alpha1-adrenergic blockers. A modest decline in the use of doxazosin and other alpha1-adrenergic-blocking drugs has occurred coincident to the early termination of the doxazosin treatment arm in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial.

Combination therapy with diuretics: an evolution of understanding

One of the current recommendations for the treatment of hypertension is a stepped-care approach in which a second drug is added to a first-line agent when adequate blood pressure control has not been achieved. It has been well demonstrated in multiple studies that the response rate to any single class of antihypertensive agent, given as monotherapy, is approximately 45-55%. Thus, in approximately half of the hypertensive population, a second drug will be required. This is not surprising, since it is now well recognized that hypertension is a multifaceted disease process. The use of combination therapy with low-dose diuretics (< 25mg hydrochlorothiazide [HCTZ] or its equivalent) has become a very attractive alternative choice to first-line therapy. The data from clinical trials clearly demonstrate that 6.25 mg or 12.5 mg HCTZ has an additive or synergistic effect on blood-pressure reduction when used in combination with most drugs. At low doses, the side-effect profile with diuretics is similar to placebo. Furthermore, metabolic side effects are significantly reduced when diuretics are used in low doses. The use of low-dose diuretics in combination with other first-line agents significantly enhances blood-pressure control and reduces the likelihood of adverse events and alteration in carbohydrate, lipid, and electrolyte metabolism. Thus, combination therapy with low-dose diuretics provides an attractive alternative approach to first-line treatment of essential hypertension.

Antihypertensive therapy in the geriatric patient: II. A review of the alpha1-adrenergic blocking agents

The prevalence of hypertension increases with age. Multiple physiologic factors are involved in the development of hypertension in the elderly. Alpha1-adrenergic blocking agents lower blood pressure through a reduction in total peripheral resistance. Prazosin, terazosin, and doxazosin have been shown to be equally effective in reducing blood pressure in older persons. The bioavailability, terminal elimination half-life, and volume of distribution of prazosin is increased in the elderly. Hybrid drugs, such as ketanserin, urapidil, and indoramin are also effective in lowering blood pressure. Ketanserin seems to have a greater effect on blood pressure reduction in persons older than 60 years of age. Alpha1-adrenergic blockers may be used safely in patients with diabetes, asthma, and hyperlipidemia.

Antihypertensive therapy

Choosing antihypertensive agents that protect patients against cardiovascular and other complications is a growing trend in the treatment of mild to moderate hypertension. Calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors are favored because they have neutral or positive effects on lipid levels and insulin resistance. The alpha 1 blockers, especially doxazosin mesylate (Cardura), are enjoying a resurgence in popularity because they have a beneficial effect on lipid levels. In terms of preserving patients' quality of life, the ACE inhibitors in particular have been shown to have a positive impact. It has been shown that systolic hypertension in elderly patients should definitely be treated, but the most appropriate agent has yet to be defined. Therapy should be tailored to the individual. The following questions should be considered when choosing an antihypertensive agent: (1) What are its side effects (especially metabolic ones)? (2) Does it require only once- or twice-a-day dosing? (3) Does it cause regression of left ventricular hypertrophy? (4) Does it prevent death from coronary artery disease? (5) How will it affect quality of life? (6) How much does it cost? The goal of therapy should be to provide adequate blood pressure control throughout the day, enhance compliance, and protect the heart, brain, and kidneys without adversely affecting metabolic state.

Enalapril. A reappraisal of its pharmacology and therapeutic use in hypertension

Enalapril, an angiotensin converting enzyme (ACE) inhibitor usually administered orally once daily, decreases blood pressure by lowering peripheral vascular resistance without increasing heart rate or output. It is effective in lowering blood pressure in all grades of essential and renovascular hypertension. Patients not responding adequately to enalapril monotherapy usually respond with the addition of a thiazide diuretic (or a calcium antagonist or beta-blocker), and rarely require a third antihypertensive agent. Enalapril is at least as effective as other established and newer ACE inhibitors, and members of other antihypertensive drug classes including diuretics, beta-blockers, calcium antagonists and alpha-blockers, but therapy with enalapril may be less frequently limited by serious adverse effects or treatment contraindications than with other drug classes. The most frequent adverse effect limiting all ACE inhibitor therapy in clinical practice is cough. This favourable profile of efficacy and tolerability, and the substantial weight of clinical experience, explain the increasing acceptance of enalapril as a major antihypertensive treatment and supports its use as logical first-line therapeutic option.

Hypertension in the aged: a pathophysiologic basis for treatment

According to major surveys, hypertension is found in over half the population aged 65 years or over. In this age group, systolic blood pressure is at least as important as diastolic blood pressure as a predictor of cardiovascular morbidity and mortality. Overall, the presence of hypertension is associated with approximately a threefold increase in the likelihood of major events. Differing factors contribute to the hypertension. Loss of proximal arterial compliance, affecting the larger conduit vessels, occurs often with aging and explains the tendency for systolic pressure to increase while diastolic pressure remains constant or even decreases. A loss of baroreceptor sensitivity also may contribute to hypertension. There is an increase in responsiveness of the sympathetic nervous system and an enhanced sensitivity to its effects in the elderly, perhaps reflecting a decline in the buffering activity of peripheral vascular beta receptors. It is possible, too, that sodium retention may contribute to hypertension in some older patients. Although diuretics traditionally have been the mainstay of treatment in these patients, it is now recognized that other classes of antihypertensive agents may be equally as effective yet less prone to metabolic or symptomatic adverse events. Sympatholytic drugs, calcium channel blockers and angiotensin-converting enzyme inhibitors, either as monotherapy or in combination with low-dose diuretics, have been shown to be efficacious in the elderly. These agents also can produce regression of left ventricular hypertrophy, an additional property that may contribute to a reduction in serious cardiac complications.