Postural hypotension chronic

Two long-term effects are theoretical considerations. One is that exposure to the cannabinoids may somehow have caused a chronic or delayed posttraumatic stress disorder. In the dosage and frequency used, this is unlikely. The postexperimental effect that was most undesirable was postural hypotension. This resulted in dizziness and faintness, from which all subjects recovered. Such a stress is Insufficient to provoke a delayed or chronic posttraumatlc stress syndrome, nor is there any evidence that any such syndrome occurred. 

Venodilators Releases nitric oxide (NO) activates guanylyl cyclase (see Chapter 12) Venodilation reduces preload and ventricular stretch Acute and chronic heart failure angina Oral 4-6 h duration Toxicity Postural hypotension, tachycardia, headache Interactions Additive with other vasodilators and synergistic with phosphodiesterase type 5 inhibitors... 

Therapeutic uses Thiazide diuretics decrease blood pressure in both the supine and standing positions postural hypotension is rarely observed, except in elderly, volume-depleted patients. These agents counteract the sodium and water retention observed with other agents used in the treatment of hypertension (for example, hydralazine). Thiazides are therefore useful in combination therapy with a variety of other antihypertensive agents including (3-blockers and ACE inhibitors. Thiazide diuretics are particularly useful in the treatment of black or elderly patients, and in those with chronic renal disease. Thiazide diuretics are not effective in patients with inadequate kidney function (creatinine clearance less than 50 mls/min). Loop diuretics may be required in these patients. 

Marijuana has several effects on the cardiovascular system, and can increase resting heart rate and supine blood pressure and cause postural hypotension. It is associated with an increase in myocardial oxygen demand and a decrease in oxygen supply. Peripheral vasodilatation, with increased blood flow, orthostatic hypotension, and tachycardia, can occur with normal recreational doses of cannabis. High doses of THC taken intravenously have often been associated with ventricular extra beats, a shortened PR interval, and reduced T wave amplitude, to which tolerance readily develops and which are reversible on withdrawal. While the other cardiovascular effects tend to decrease in chronic smokers, the degree of tachycardia continues to be exaggerated with exercise, as shown by bicycle ergometry. 

Postural hypotension (characteristic of a-receptor blockade) is liable to occur at the outset of therapy and if the dose is increased too rapidly. But with chronic therapy when the P-receptor component is largely responsible for the antihypertensive effect, it is not a problem. 

Severe postural hypotension has been observed in patients given both isosorbide dinitrate and hydralazine for chronic heart failure (26), although this has not been a problem in large studies (90). 

Massie B, Kramer B, Haughom F. Postural hypotension and tachycardia during hydralazine-isosorbide dinitrate therapy for chronic heart failure. Circulatiou 1981 63(3) 658-64. 

Drugs Used in the Treatment of Chronic Postural Hypotension... 

Symptoms of dizziness and syncope due to postural hypotension may result from dehydration, blood loss, and myocardial disease. However, the most important cause of chronic recurrent symptomatic postural hypotension is failure of the autonomic nervous system. The drug treatment for postural hypotension is difficult because the response varies and tolerance to drugs develops. Patients with autonomic abnormalities may suffer symptoms after eating, and this further hampers treatment. 

Chronic moderate to heavy drinking raises the blood pressure and reduces, to some extent, the effectiveness of antihypertensive drugs. A few patients may experience postural hypotension, dizziness and fainting shortly after having drank alcohol. Alpha blockers may enhance the hypotensive effect of alcohol in subjects susceptible to the alcohol flush syndrome. 

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