[Serotonin receptor subtypes. Considerations on their physiological role and therapeutic prospects]

Recent evidence for the existence of different types and subtypes of serotoninergic receptors has been reviewed. Presently, 5-TH receptors have been divided into 5-HT1, 5-HT2 and 5-HT-3. 5-HT1 receptors have been subdivided into 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D. The development of specific agonists and antagonists to these different types of receptors suggests the possibility of a selective use of these drugs in the treatment of various disorders.

Acute respiratory and cardiovascular effects of inhaled ketanserin in chronic obstructive pulmonary disease. A comparative study with intravenously administered ketanserin

In a double-blind, crossover study, nebulized ketanserin, a 5-HT2 receptor antagonist, and a placebo were given to eight patients with moderate to severe nonasthmatic COPD. Intravenous ketanserin had rapid onset of action and induced a longer lasting bronchial response than inhaled ketanserin. These results confirm that ketanserin acts as a mild bronchodilator in patients with COPD and demonstrate that the inhaled route has no advantage over the intravenous route in terms of effectiveness. Thus, 5-HT may play a role in bronchomotor tone, at least in patients with chronic airway obstruction.

Ketanserin in the treatment of diabetic foot ulcer with severe peripheral vascular disease

The aim of this study was to evaluate if ketanserin, a selective serotoninantagonist, could improve wound healing in diabetic patients with foot ulcers and severe peripheral vascular disease. In a double blind study 40 diabetic patients with foot ulcer and a systolic toe pressure below 45 mmHg were randomly allocated to either ketanserin (20-40 mg three times a day) or placebo for a period of 3 months. The treatment was carried out on an out-patient basis by a combined medical/orthopedic foot care team at the Department of Internal Medicine, University Hospital, Lund, Sweden. Both groups were comparable regarding age, sex, duration and treatment of diabetes, cardiovascular disease and type of lesion. Wound healing (defined as intact skin for at least 3 months) or wound size reduction of 50% or more were sen in 11 out of 19 (58%) in the ketanserin group and in 7 out of 19 (37%) in the placebo group. Gangrene developed in 6 patients with placebo and 2 with ketanserin. Two patients died during the study and their ulcers were not evaluated. The systolic toe pressure was measured at admission, at end of run in, after 1 month and 3 months with strain gauge technique. Only one out of nine patients (11%) with a toe pressure below 30 mmHg in the placebo group healed or improved their ulcers compared to nine out of 16 (56%) in the ketanserin group. The healing rate in the ketanserin group was higher than expected considering the lower systolic toe pressure in this group compared to placebo at randomization (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of urapidil, ketanserin and sodium nitroprusside on venous admixture and arterial oxygenation following coronary artery bypass grafting

Thirty patients who developed arterial hypertension following coronary artery bypass grafting, despite sedation, were treated randomly with sodium nitroprusside (SNP), ketanserin or urapidil. All drugs significantly decreased arterial pressure. Two patients were withdrawn because hypertension failed to respond to ketanserin. Significant tachycardia was noted only in the SNP group. An increase in Q and significant decreases in systemic and pulmonary vascular resistances were seen in all groups. Following administration of SNP, (PaO2-PaO2) and Qs/Qt increased significantly, whereas PaO2 decreased significantly. Three patients were withdrawn from the SNP group because Qs/Qt was greater than 30%. (PAO2-PaO2) and Qs/Qt showed no significant changes following the administration of ketanserin or urapidil. These drugs may have advantages over SNP in the management of hypertension following coronary artery bypass surgery.

Antihypertensive therapy with ketanserin: effects on central and renal hemodynamics, and microalbuminuria

Ten patients with essential hypertension and normal renal function were treated with ketanserin (20-40 mg twice a day), administered for 8 weeks. In all patients, the changes in systemic and renal hemodynamics, and in urine albumin excretion, were assessed. Ketanserin monotherapy effectively lowered blood pressure in all patients. No change in cardiac output, pulse rate and stroke volume was observed; peripheral vascular resistance was significantly decreased. Plasma volume was unaltered. Renal plasma flow, glomerular filtration rate and filtration fraction were stable, with a slight but not significant reduction in renal vascular resistance. Urine albumin excretion remained unchanged. No relevant side effects were observed during the treatment period. In conclusion, our results confirm that ketanserin alone is an effective antihypertensive agent in patients with uncomplicated essential hypertension. The blood pressure lowering effect is mainly due to the systemic vasodilatation; renal hemodynamics and function are well preserved.

Effect of ketanserin on pain perception in arterial hypertension

An association between increased tolerance to pain and arterial hypertension has been reported in experimental animals and confirmed in humans. The underlying mechanisms remain elusive. We have recently reported that diuretics and beta-blocking treatment do not influence pain sensitivity, despite significant reductions in arterial blood pressure. In the present study, ketanserin was evaluated. As in previous work, pain perception was assessed with a tooth pulp tester. Ten hypertensive subjects were studied basally, after 15 days and after 3 months of ketanserin treatment (20 mg twice daily). Significant reductions in arterial blood pressure and of pain thresholds were observed, but no correlation between these changes occurred. These preliminary data indicate that, contrary to other hypotensive drugs, ketanserin tends to decrease or reverse the abnormality in pain modulation observed in hypertensive patients. The lack of a correlation between effects on blood pressure and pain sensitivity seems, however, to favor the hypothesis of two independent underlying mechanisms.

Effects of ketanserin on intraocular pressure

There is evidence that some antihypertensive drugs, such as beta blockers, are effective in reducing intraocular pressure (IOP) and are commonly used in the medical treatment of glaucoma. The aim of this study was to evaluate the effects of the anti-serotonergic agent ketanserin, which has associated alpha 1-blocking properties, on IOP in normotensive and hypertensive eyes. The first part of the study was performed in six arterial hypertensive patients (mean +/- SD blood pressure 156/102 +/- 10/6 mmHg) with a pretreatment IOP in the normal range (15.7 +/- 1 mmHg). Both blood pressure and IOP were measured at baseline and at 1 hour intervals up to 3 hours following the oral administration of ketanserin 20 mg or placebo, given in a randomized manner. Three hours after ketanserin treatment, mean systolic and diastolic blood pressures dropped by 10/5 mmHg and mean IOP was reduced by 2.7 mmHg; after placebo, no change was observed in these variables. Thereafter, four normotensive patients with chronic open-angle glaucoma (IOP = 22.8 mmHg) were given 20 mg ketanserin orally. Three hours after administration, a 22% reduction in mean IOP occurred (-5.8 mmHg), with a concomitant reduction in mean systolic blood pressure of 13.0 mmHg. These results indicate that ketanserin treatment reduces IOP and systemic blood pressure. Further, long-term studies are needed in order to confirm the efficacy of ketanserin in the medical treatment of ocular hypertension.

Could the increased antihypertensive efficacy of ketanserin in the elderly be due to altered pharmacokinetics?

Ketanserin is a serotonin S2-receptor antagonist that is an effective antihypertensive agent with a greater blood pressure reduction in older patients. We have reviewed the data from two studies of ketanserin pharmacokinetics in elderly patients, one in general practice (GP) and one in hospital patients. We compared these data with the results from two of our previous studies in young volunteers. The purpose was to determine whether the enhanced efficacy of ketanserin in elderly hypertensive patients could be due to altered pharmacokinetics. After a single dose of ketanserin, elderly hypertensives showed about a 60% increase in bioavailability compared with young volunteers. This increase is likely to be explained by a reduced metabolism of ketanserin on first pass through the liver. The elimination half-life of ketanserin was found to be longer in elderly hospital outpatients, but not in our elderly subjects in general practice. This prolongation of the elimination half-life of ketanserin appears to be unrelated to age, since the hospital outpatient elderly and elderly subjects in general practice were of similar ages. The elimination half-life of ketanserinol was longer in the hospital elderly subjects. This probably reflects a slight diminution of renal function in the elderly hospital outpatients, resulting in reduced clearance of ketanserinol. The peak and trough ketanserin concentrations were similar in young and elderly subjects during chronic treatment, and it is therefore unlikely that the increased efficacy of ketanserin in elderly patients is due to altered pharmacokinetics.

Regression of left ventricular hypertrophy and systolic function in hypertensive patients during long-term treatment with ketanserin

It is now generally accepted that antihypertensive therapy can induce regression of left ventricular hypertrophy (LVH) in hypertensive subjects. However, the influence of LVH reversal on both the systolic and diastolic functions, and particularly the ability of the heart to meet sudden overloads caused by exercise and/or recurrence of hypertension, remain unanswered questions. The long-term effects of ketanserin, a selective serotonin S2-receptor antagonist with additional alpha 1-adrenergic blocking properties, on LVH and systolic function were studied in 13 untreated subjects (age range 35-55 years) with mild-to-moderate essential hypertension, echocardiographic evidence of LVH, and normal ejection fraction. Blood pressure values and echocardiographic measurements of dimensions, wall thicknesses, and indices of LV mass were determined before and after 3, 6, and 12 months treatment; ejection fractions at rest and during exercise were evaluated by equilibrium multigated radionuclide angiocardiography at baseline and after 12 months of therapy. Mean arterial pressure was significantly reduced from the first month of treatment (p less than 0.001) and remained well controlled up to the end of the trial. Both posterior and septum wall thicknesses decreased after 3 months of therapy and remained stable throughout the whole study period. LV mass index decreased from a mean +/- SD of 187.7 +/- 47.6 g/m2 to a mean of 157.81 +/- 31.63 g/m2 (p less than 0.01) at the third month, reaching greater decreases after 6 months (156.05 +/- 31.00 g/m2) and after 12 months (153.21 +/- 28.80 g/m2) of treatment. A significant correlation was found between LV mass and posterior wall thickness at the different observation times in the study. Finally, the regression of LVH at the end of therapy was not associated with impairment of systolic function, as assessed by measurements of ejection fraction at rest and during exercise.

Effects of ketanserin on microhemodynamics and hemorheology in patients with essential hypertension

Ketanserin, a serotonin antagonist, has recently been developed. This agent produces antihemagglutination and dilation of blood vessels. Blood pressure is also lowered by ketanserin. We investigated the effect of ketanserin on microhemodynamics and hemorheology in essential hypertension. Twenty patients with essential hypertension (8 males; 12 females; average age +/- SE-56.2 +/- 2.5 years). A single dose of 10 mg ketanserin was given orally to each patient, without breakfast, on the experiment day. Ketanserin treatment resulted in: redution in systolic and diastolic blood pressure; significant decrease in heart rate; increase in arteriole and venule internal diameters; increase in blood flow velocities and blood flow volumes; significant decreases in whole blood viscosities at high shear rate (94.5 sec-1) and at low shear rate (0.376 sec-1), with no change in plasma viscosities; significant shortening of plasma passage times; and marked decreases in blood concentrations of total protein, albumin, and globulin. These data suggest that ketanserin beneficially affects microhemodynamics and hemorheology.

A placebo-controlled crossover study of ketanserin in elderly hypertensive patients

The results of the European Working Party for Hypertension in the Elderly Study showed that treatment of high blood pressure reduced the morbidity and mortality from strokes and myocardial infarction and reduced the incidence of heart failure in elderly patients. The largest number of hypertensive patients are elderly, and it is in this group of patients that the maximum benefit of treatment might be expected. The present study was designed to study in detail the efficacy and tolerability of ketanserin in an elderly population. Seventeen elderly (greater than 70 years) patients with a lying systolic blood pressure of 160 mmHg and/or a diastolic blood pressure of greater than or equal to 90 mmHg were included in the study. For the 12 patients who completed the study, the mean blood pressure was significantly reduced on ketanserin compared with placebo (p less than 0.001) in the supine and erect positions. The mean net changes in blood pressure after 8 weeks were 21/17 mmHg and 23/16 mmHg erect. Heart rate was also significantly reduced (p less than 0.001) by a mean of 8 beats/min lying and 9 beats/min erect. Analysis of ambulatory 24-hour ECG tapes showed no significant effect of ketanserin on heart rhythms. Ketanserin therapy had no significant effect on routine hematology, plasma electrolytes, biochemistry, or urinalysis. Total exchangeable sodium and potassium and body weight were also unchanged. On ketanserin treatment, the overall quality of life score was significantly improved (p = 0.002; analysis of variance on log transformed data) compared with the placebo phase.

The effects of ketanserin on ventricular ectopic activity in humans

Ketanserin is a serotonin S2-receptor antagonist that lowers blood pressure and inhibits platelet aggregation. Ketanserin treatment is also associated with prolongation of the corrected QT interval. The recently reported Prevention of Atherosclerotic Complications with Ketanserin (PACK) trial confirmed this prolongation of QT and also revealed a significant excess of deaths in patients receiving ketanserin together with potassium-losing diuretics. The investigators suggested that this excess of deaths may have been attributable to exacerbation of hypokalemia-induced ventricular arrhythmias by the repolarization-prolonging effect of ketanserin. However, drugs that prolong the QT interval may affect ventricular ectopic activity beneficially, and our study was designed to evaluate the effects of ketanserin on ventricular ectopic activity. Twenty patients (18 male, 2 female) aged 42-73 years were studied, each having at least 15 ventricular ectopic beats/hour. The study design was a double-blind, crossover comparison of ketanserin, 40 mg twice daily, and placebo, both given for 1 week. Ventricular ectopic activity was assessed by 48-hour Holter electrocardiogram (ECG) tapes at the end of each treatment period. Ketanserin treatment was associated with prolongation of repolarization, as reflected by the significant mean increases in both QT interval (+30 ms; p less than 0.001) and corrected QT interval (+20 ms; p less than 0.05). The mean overall degree of ventricular ectopic activity, as represented by a score based on the Lown classification, was significantly reduced (p less than 0.05). This was associated with a concordant improvement in the individual indices of ectopic activity. Our results show that ketanserin significantly suppressed ventricular ectopic activity in our normokalemic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral dosing with ketanserin to control high blood pressure in the elderly

Ketanserin is the prototype of a new class of antihypertensive drugs based on a selective blockade of serotonin S2 receptors. A number of controlled trials have indicated that ketanserin is more effective in older than in younger subjects and that, in the elderly, ketanserin may be even more effective than other antihypertensive drugs. We set up a large multicenter trial to compare the two most common dosages of ketanserin (20 mg and 40 mg twice daily) in patients of 60 years of age and over. In these patients, blood pressures were elevated systolically (SBP greater than or equal to 160 mmHg), diastolically (DBP greater than or equal to 95 mmHg), or both, and any existing antihypertensive medication was continued at a constant dosage. The total duration of the trial was 3 months and monthly control visits were held. Throughout the Netherlands, 252 general practitioners participated in the trial, which included 462 evaluable patients. After 1 month of open treatment with 20 mg ketanserin twice daily, blood pressure was found to be fully normalized in 18% of patients, while the proportion of patients with both systolic and diastolic hypertension was reduced from 89% to 50%. In three out of four patients, an adequate and maximal fall in blood pressure was reached only after 2-3 months of treatment. In such patients, raising the ketanserin dose from 20 mg to 40 mg twice daily did not result in any faster or improved antihypertensive response. A number of symptoms related to peripheral circulatory disturbances, or possibly to hypertension itself, markedly improved during oral treatment with ketanserin.

Ketanserin and captopril interaction in the treatment of essential hypertensives

The aim of the study was to evaluate whether the combination of ketanserin with captopril exerts an additive antihypertensive effect, as compared with single drug treatment. Twelve patients with uncomplicated moderate essential hypertension received, according to a randomized, double-blind, crossover design, ketanserin (40 mg twice daily), captopril (50 mg twice daily), the combination of the two drugs at these dosages, and the corresponding placebo, each treatment being given for 1 month. Both ketanserin and captopril as monotherapy similarly and significantly reduced blood pressure as compared with placebo (p less than 0.001). The combination treatment of ketanserin plus captopril further and significantly reduced blood pressure when compared with single drug treatment (p less than 0.001). Moreover, the percentage of responders and patients whose blood pressure was normalized were significantly greater under the combined treatment than under ketanserin or captopril monotherapy (p less than 0.001). These data indicate that the combination of ketanserin plus captopril exerts a clear additive antihypertensive effect when compared with each treatment as monotherapy, a finding that suggests this combination can be usefully employed in the treatment of hypertensive patients.

Effects of ketanserin on left ventricular hypertrophy in hypertensive patients

Ketanserin, a serotonergic S2-receptor antagonist, was used in a prospective study in nine hypertensive patients with ECG criteria of left ventricular hypertrophy (LVH). Echocardiographic measurement with M mode was made after 1 month of placebo, and after 3, 6, and 12 months of ketanserin treatment as monotherapy at a mean dose of 31 mg bid. Ketanserin treatment decreased mean left ventricular mass by 9.3% at 3 months (not significant), by 15.3% at 6 months (p less than 0.008), and by 26.2% at 12 months (p less than 0.02), with a tendency towards improvement in left ventricular ejection fraction, which was not statistically significant. The study showed a sustained effect upon regression of LVH in hypertensives, with preservation of left ventricular function.

Left ventricular hypertrophy regression and function changes with ketanserin in elderly hypertensives

Ketanserin is a serotonin antagonist with age-related antihypertensive efficacy. Its effects on left ventricular (LV) function and hypertrophy have not been adequately reported. We studied noninvasively 54 elderly hypertensives before and 6 months after ketanserin monotherapy. Mean blood pressure was controlled (174/101 to 145/86 mmHg, p less than 0.0001) with no heart rate changes. LV dimensions and volumes remained unchanged, as did all LV ejection indices, thus preserving LV output (p = ns). Total peripheral resistances fell (from means of 1986 to 1615 dynes, cm.s-5, p less than 0.0001), as did LV systolic wall stresses. Mean LV mass was reduced (248 to 237 g, p less than 0.0001), mainly due to interventricular septum thinning (11.8 to 11.1 mm, p less than 0.0001), resulting in a decrease in mean LV cross-sectional area (21.3 to 20.5 cm2, p less than 0.0001) and mass/volume ratio (2.14 to 2.01 p = 0.0001). Thus, LV hypertrophy regression did not affect contractility (LV mass index relation to stress/end-systolic volume index, r = -0.558 before and r = -0.564 after ketanserin therapy). It is concluded that ketanserin is an effective antihypertensive agent in the elderly that reduces LV hypertrophy indices and maintains cardiac output, with no concomitant burdening on LV hemodynamics.

Comparison of ketanserin and enalapril in the treatment of mild-to-moderate essential hypertension

In a double-blind 3-month study in mild-to-moderate essential hypertensive patients over 50 years of age, ketanserin, a selective S2-serotoninergic antagonist with additional alpha 1-adrenergic blocking properties, has been compared with enalapril, an angiotensin-converting enzyme inhibitor. Supine and upright blood pressures and heart rates were recorded for placebo and during active treatment (-4, -2, 0, 2, 4, 6, 8, 10, and 12 weeks). Metabolic profile (plasma glucose, creatinine, sodium, potassium, total and HDL-cholesterol, triglycerides, uric acid) was monitored during treatment with placebo and at the end of the study. Mean blood pressure was equally and significantly (p less than 0.001) lowered by both drugs from 2 weeks of treatment, whereas no changes occurred in mean heart rate or in biochemical variables. Dizziness was observed in three patients on ketanserin and in one patient on enalapril, whereas headache occurred in only one patient on enalapril. These data indicate that ketanserin is as effective and well tolerated as enalapril in hypertensive patients over 50 years of age.

Influence of long-term treatment with ketanserin on blood pressure, pulmonary artery pressure, and cardiac output in patients with heart failure

Ketanserin is a selective serotonin2-receptor blocker and by this mechanism decreases peripheral resistance and blood pressure in hypertensives. We examined the hemodynamic effects of ketanserin during long-term treatment in patients with heart failure. Five male patients with coronary artery disease and heart failure (NYHA classes II-III) were treated with ketanserin (80 mg daily) for 12 months. Before treatment, after 4 weeks, and after 12 months treatment, a Swan-Ganz catheter was placed into the pulmonary artery and pulmonary wedge pressure, cardiac output, mean arterial pressure, and heart rate were measured at rest and on exertion. The pulmonary wedge pressure at rest decreased from 8 mmHg before to 6 mmHg after 4 weeks and 12 months treatment; on exertion, it decreased from 31 mmHg before treatment to 24 mmHg after 4 weeks treatment and to 21 mmHg after 12 months treatment. The mean arterial pressure also decreased at rest and on exertion after 4 weeks treatment as well as after 12 months treatment. Cardiac output increased slightly and heart rate was unaltered. No serious side effects occurred. Ketanserin could become an alternative vasodilator drug in the treatment of patients with heart failure.

Carcinoid syndrome and serotonin: therapeutic effects of ketanserin

The carcinoid syndrome can arise when effluent blood from carcinoid tumor tissue gains access to the systemic, as opposed to the portal, venous system. Features include facial flushing, diarrhea, wheezing, right-sided cardiac lesions, and retroperitoneal fibrosis. Attacks of flushing, diarrhea, and wheezing can be provoked by bolus injections of adrenaline, noradrenaline, or pentagastrin. While serotonin usually predominates, carcinoid tumors can also secrete, in varying proportions, 5-hydroxytryptophan, kallikrein, kinins, substance P and other neuropeptides, prostaglandins, catecholamines, and histamine. Of these, serotonin, kinins, histamine, and substance P are possible mediators of flushes; serotonin and substance P of hyperperistalsis; and serotonin, kinins, or histamine of bronchial constriction. Despite the gross excess of circulating serotonin, nearly all is platelet bound and therefore inactive. Very little is free in plasma. Demonstration of a contribution of serotonin to carcinoid attacks requires assay of free plasma serotonin; measurements of whole blood or serum serotonin are of little value. Some, but not all, provoked flushes have been shown to be accompanied by a rise in free plasma serotonin or substance P; an increase in circulating kinins has been more consistently shown. The 5HT2 antagonist ketanserin has been found to inhibit both provoked and spontaneous attacks of flushing, diarrhea, and dyspnea in a proportion of patients with carcinoid syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Randomized placebo-controlled, double-blind trial of ketanserin in claudicants. Changes in claudication distance and ankle systolic pressure. PACK Claudication Substudy

The effect of ketanserin on intermittent claudication (measured by treadmill walking distance and ankle systolic pressure) was assessed in 594 patients, a subset of the 3,899 patients who composed a double-blind study of the effect of ketanserin on cardiovascular events. Complete data sets at the beginning and end of 1 year's treatment with ketanserin or placebo were available in 436 patients. There was no difference between the groups in the improvement in pain-free treadmill walking distance. The placebo effect on treadmill walking distance increased continuously for at least 1 year at the rate of about 15% every 6 months. There was no significant change in either group in the ankle systolic pressure at the end of the treatment period but in the group given ketanserin, brachial systolic pressure was decreased and the ankle to arm systolic pressure ratio therefore increased. There was only a very weak association between treadmill walking distance and ankle to arm systolic pressure ratio both at the beginning and in terms of change over 1 year. Therefore, this pressure ratio is probably not a useful way of assessing the effects of medical treatment of claudication.

An evaluation of ketanserin therapy for the hypertensive diabetic patient

Hypertension may accelerate the development of the vascular complications of diabetes but many conventional antihypertensive agents have adverse effects on glucose tolerance or peripheral perfusion. To investigate the potential of ketanserin as an antihypertensive agent for hypertensive diabetics we performed a randomly allocated, double-blind, placebo-controlled trial in 17 patients. A range of peripheral blood flow responses was determined using laser Doppler flowmetry, and diabetic control was assessed at the time of allocation to groups and after 8 weeks' therapy (20 mg twice a day for 2 weeks; 40 mg twice a day for 6 weeks). The mean decrease in standing blood pressure was 14.1/9.3 mmHg (ketanserin treatment) versus 7.1/5.9 mmHg (placebo). The maximum skin blood flow and a posturally induced vasoconstriction of the foot skin were unaffected by the therapy, and glycaemic control was unchanged. Ketanserin was well tolerated. These studies suggest that ketanserin may be a useful agent for the treatment of hypertension in the diabetic patient.

Ketanserin in the treatment of systemic hypertension during and following coronary artery bypass surgery

One of the most important problems during cardiac surgery is the prevention and treatment of hypertension, occurring in 40-60% of the patients following coronary artery bypass surgery (CABS). Hypertension should be avoided to prevent myocardial damage, neurologic complications, increased blood loss, and premature graft closure due to intimal damage. During and following cardiac surgery hypertension is routinely treated with vasodilating agents, which generally induce reflex tachycardia and increased intrapulmonary shunting. The results obtained with ketanserin, a specific S2-serotonergic receptor blocker with alpha 1-adrenergic receptor blocking properties, in the prevention and treatment of hypertension in patients undergoing cardiac surgery, are presented. Ketanserin effectively lowers blood pressure by decreasing systemic vascular resistance but does not completely prevent perioperative and postoperative hypertension when administered as a continuous infusion from the start of anesthesia. In contrast to sodium nitroprusside, ketanserin does not induce reflex tachycardia in the treatment of postoperative systemic hypertension following CABS. The compound improves diuresis and perfusion of the skin perioperatively. Ketanserin is devoid of rebound phenomena after its administration is stopped. It is postulated that the antihypertensive effect of ketanserin can be explained by its property of simultaneously blocking alpha 1-adrenergic and S2-serotonergic receptors.

[The effect of pharmacologic blockade of serotonin receptors (S2) on arterial pressure in rats with 2 forms of hereditary arterial hypertension]

The influence of blockade of serotonin S2 receptors with ketanserin was studied in two strains of rats with inherited arterial hypertension: spontaneously hypertensive rats (SHR strain) and rats with inherited stress-induced arterial hypertension (ISIAH strain). It was found that peripheral injection of ketanserin produced a greater decrease of arterial blood pressure than i.c.v. administration. ISIAH rats were more sensitive to the hypotensive effect of ketanserin when compared to normotensive Wistar or SHR rats.