Hydralazine drug administration

Most side effects associated with hydralazine administration are due to vasodilation and the reflex hemodynamic changes that occur in response to vasodilation. These side effects include headache, flushing, nasal congestion, tachycardia, and palpitations. More serious manifestations include myocardial ischemia and heart failure. These untoward effects of hydralazine are greatly attenuated when the drug is administered in conjunction with a (3-blocker. 

The hemodynamic effects of diazoxide are similar to those of hydralazine and minoxidil. It produces direct relaxation of arteriolar smooth muscle with little effect on capacitance beds. Since it does not impair cardiovascular reflexes, orthostasis is not a problem. Its administration is, however, associated with a reflex increase in cardiac output that partially counters its antihypertensive effects. Propranolol and other -blockers potentiate the vasodilating properties of the drug. Diazoxide has no direct action on the heart. Although renal blood flow and glomerular filtration may fall transiently, they generally return to predrug levels within an hour. 

Certain autoimmune syndromes can be induced by drugs. Examples include systemic lupus erythematosus following hydralazine or procainamide therapy, "lupoid hepatitis" due to cathartic sensitivity, autoimmune hemolytic anemia resulting from methyldopa administration, thrombocytopenic purpura due to quinidine, and agranulocytosis due to a variety of drugs. As indicated in other... 

Hydralazine is the first systemic vasodilator drug advocated for initial treatment in patients with primary pulmonary hypertension. Rubin and Peter (1980) reported that short-term and long-term administration of hydralazine (200-300 mg/day) improved hemodynamics during rest and exercise in patients with primary pulmonary hypertension. The use of hydralazine, however, is not without hazard. In one study with 13 patients (Danahy et al., 1979), hydralazine produced only modest decreases in pulmonary arteriolar resistance and serious adverse effects that included hypotension (resulting in one death), renal insufficiency, and systemic arterial hypoxemia. 

Questions 13 to 46 using the blood pressure trace (see Figure below), answer each question. Consider cardiac reflexes in your answer. Each letter represents the administration of a drug, allowing sufficient time for recovery. The drugs used are propranolol, hydralazine, clonidine, and prazosin. 

Hydralazine (apresoline) causes direct relaxation of arteriolar smooth muscle, possibly secondary to a fall in intracellular Ca concentrations. The drug does not dilate epicardial coronary arteries or relax venous smooth muscle. Hydralazine-induced vasodilation is associated with powerful stimulation of the sympathetic nervous system, likely due to baroreceptor-mediated reflexes, which results in increased heart rate and contractility, increased plasma renin activity, and fluid retention all of these effects counteract the antihypertensive effect of hydralazine. Although most of the sympathetic activity is due to a baroreceptor-mediated reflex, hydralazine may stimulate NE release from sympathetic nerve terminals and augment myocardial contractility directly. Most of hydralazine s effects are confined to the cardiovascular system the decrease in blood pressure after administration is associated with a selective decrease in vascular resistance in the coronary, cerebral, and renal circulations, with a smaller effect in skin and muscle. Because of preferential dilation of arterioles, postural hypotension is not common, and hydralazine lowers blood pressure equally in the supine and upright positions. 

Several pharmaceutical formulations that contain a P-blocker, together with one or two diuretics, are commercialized. Some of these preparations also include the vasodilator hydralazine. The combination of the three types of drugs has an additive effect in the treatment of hypertension, producing the diminution of arterial pressure through diverse mechanisms. The simultaneous administration of these drugs is recommended, when an appropriate control of hypertension is not possible with each of them separately. 

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