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PubMed1990

Indoramin in the treatment of pregnancy hypertension. A placebo-controlled trial comparing the efficacy of indoramin with alpha-methyldopa.

A placebo-controlled trial was used to assess the antihypertensive efficacy of indoramin in the management of pregnancy hypertension. Sixty patients were recruited into the study and only 17 attained satisfactory blood pressure control. In the doses of drugs administered indoramin was not shown to be more effective than alpha-methyldopa.

Drug Therapy, Combination↗

PubMedDate not supplied

Pre- and postsynaptic effects of indoramin on sympathetic neuroeffector transmission in rabbit aorta and pulmonary artery.

The effects of indoramin on sympathetic neuroeffector transmission in rabbit isolated blood vessels were examined. Indoramin reduced the contractions of pulmonary artery evoked by electrical-field stimulation. The IC50 was 7.4 X 10(-8) M. In the presence of cocaine + corticosterone + propranolol, the IC50 was 5 X 10(-7) M. Amphetamine did not antagonize the steady-state inhibition caused by indoramin. Indoramin caused a slight enhancement of the field-stimulation-evoked 3H-overflow from pulmonary artery preloaded with 3H-noradrenaline. In the presence of cocaine + corticosterone + propranolol, indoramin also enhanced the stimulation-evoked 3H-overflow slightly. The effect of indoramin on stimulation-evoked 3H-overflow depended only slightly on stimulation frequencies (1-30 Hz): small enhancement at 1 Hz and nonsignificant changes at 3-30 Hz. Pretreatment with indoramin did not attenuate the inhibitory effect of clonidine on the stimulation-evoked 3H-overflow seen with bretylium. Indoramin and desmethylimipramine reduced the 3H-accumulation by aorta preloaded with 3H-noradrenaline. The IC50 was 3 X 10(-5)M (indoramin) and 10(-8)M (desmethylimipramine). Indoramin inhibited the contractions of aorta evoked by noradrenaline, phenylephrine, histamine and serotonin in a competitive manner. The corresponding pA2 values were 7.54, 7.98, 7.45, and 6.61. Indoramin decreased the maximal contractions of rabbit aorta evoked by potassium. These results suggest that indoramin is a potent competitive antagonist of postsynaptic alpha 1-adrenoceptors, while it may only have a slight inhibitory effect on presynaptic alpha 2-adrenoceptors. Indoramin is devoid of bretylium-like adrenergic neurone blocking activity, while it may act as reserpine. It is a weak inhibitor of the uptake-1 mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic Fibers↗

PubMed1986

A double-blind comparison of indoramin and pindolol added to hydrochlorothiazide for the treatment of mild to moderate hypertension.

Sixty patients with mild to moderate essential hypertension, uncontrolled with diuretics alone, were evaluated in a double-blind randomized study that compared the effect of indoramin plus hydrochlorothiazide with that of pindolol plus hydrochlorothiazide. Following a 2-week period during which the patients were treated with 50 mg/day of hydrochlorothiazide, the patients were treated either with indoramin, 50-100 mg/day (n = 29), or with pindolol 10-20 mg/day (n = 30), in addition to the diuretic for 12 weeks. Systolic and diastolic blood pressures were significantly reduced after 2 weeks of treatment with indoramin or pindolol; blood pressure reduction was maintained for the 12 weeks of treatment. There were no significant differences between the indoramin and pindolol groups with respect to the changes in blood pressure. Blood pressure was controlled (less than or equal to 90 mm Hg) in 70% of the indoramin-treated patients and in 80% of the pindolol-treated patients. The difference was not significant. Heart rate was reduced after pindolol but not after indoramin. Side effects occurred in 20 patients (67%) treated with indoramin and in 14 patients (47%) treated with pindolol; the difference between the groups was not significant. Eight patients in the indoramin group and 10 patients in the pindolol group withdrew before completion of the study. In the indoramin group, four patients withdrew because of side effects and four because of lack of efficacy. In the pindolol group, five patients withdrew because of side effects and three because of lack of efficacy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Antihypertensive therapy with indoramin in the elderly.

The antihypertensive efficacy and safety of indoramin, an alpha 1-adrenergic antagonist, were evaluated in 215 elderly patients. Data were collected from patients aged 60 years and older who were treated under similar protocols with indoramin administered alone (n = 58) or in combination with a thiazide diuretic (n = 157). After at least 6 months of treatment, the mean daily dosage of indoramin was higher among patients who received indoramin alone (122 mg/day) than among those who received indoramin plus a diuretic (92 mg/day). Mean supine blood pressure decreased (p less than 0.001) from 174/105 to 152/191 mm Hg in indoramin-treated patients and from 179/101 to 150/91 mm Hg in patients who were treated with indoramin plus a diuretic. Clinically satisfactory blood pressure decreases occurred in the majority of the patients who received indoramin, either alone (69%) or with a diuretic (75%). Both treatments were well tolerated by elderly patients; only 15 patients (7%) discontinued therapy because of adverse effects. Drowsiness, fatigue, and dizziness were the most frequently reported side effects. The results of this analysis indicate that indoramin, administered alone or in combination with a thiazide diuretic, is a safe and effective therapeutic regimen for elderly hypertensive patients.

Age Factors↗

PubMed1992

Is indoramin an effective alternative to prostatectomy?

Alpha-1-adrenergic antagonists are recommended for symptomatic treatment of patients awaiting prostatic surgery. Their efficacy has been confirmed in placebo controlled clinical trials, but to date no comparison of their effects with the results of subsequent prostatectomy has been made. Fifty-five patients awaiting prostatectomy were assessed (by symptom scores and peak urinary flow rates) prior to treatment, on indoramin 20 mg bd, and 2 months following prostatectomy. Side effects while taking indoramin were experienced by 36% of patients. Despite an overall improvement in mean symptom scores, 26% of patients with obstructive and 30% of those with irritative symptoms who were assessed while taking indoramin failed to experience any improvement. Of the 31 patients assessed while on indoramin and again following surgery, prostatectomy produced a greater symptomatic relief than indoramin. The increase in peak flow rate following prostatectomy was 11.7 ml/s compared with 3.2 ml/s on indoramin. However, 5 patients preferred to continue taking indoramin rather than proceeding to surgery. Indoramin is no substitute for prostatectomy. Although some patients might benefit from treatment while awaiting surgery, significant side effects may severely restrict its use for this purpose. The response to indoramin cannot be used as an accurate predictor of response to prostatectomy.

Humans↗

PubMed1986

Investigation into the cardioregulatory properties of the alpha 1-adrenoceptor blocker indoramin.

The cardioregulatory properties of the alpha 1-adrenoceptor blocker indoramin have been compared with those of prazosin in the anaesthetized rat. The effects of autonomic blockade on heart rate responses evoked by these two agents and their effects on blood pressure and heart rate after peripheral or central administration have been compared. Cumulative administration of indoramin (0.8-25.6 mg kg-1 i.v.) evoked significant decreases in arterial blood pressure and a concomitant bradycardia. Pithing or autonomic blockade, by pretreatment with a combination of practolol and bilateral vagotomy, prevented the bradycardia evoked by indoramin (0.8-3.2 mg kg-1 i.v.). Atropine sulphate pretreatment abolished the bradycardia until a cumulative dose of 25.6 mg kg-1(i.v.) of indoramin had been reached. Bilateral vagotomy, intravenous administration of atropine methylnitrate or practolol pretreatment attenuated the bradycardia. Prazosin (0.02-0.64 mg kg-1 i.v.) evoked a fall in arterial blood pressure of similar magnitude to that observed following indoramin. A bradycardia was evoked only at a relatively high dose (0.64 mg kg-1 i.v.). Intracisternal injection of indoramin or prazosin evoked bradycardia and hypotension at a dose which had no effect after intravenous injection (25 micrograms). Intracerebroventricular injection of indoramin (25 micrograms) had no significant effect on heart rate or blood pressure compared to control values, whereas prazosin (25 micrograms) evoked a significant tachycardia and hypotension. It is concluded that the bradycardia evoked by indoramin in the rat is not due to a direct action on the heart except possibly at high doses. Central alpha 1-adrenoceptor blockade, possibly in the brainstem region, results in a bradycardia and this may explain the lack of reflex tachycardia following the administration of indoramin.

Animals↗

PubMed1990

A review of the clinical pharmacokinetics and metabolism of the alpha 1-adrenoceptor antagonist indoramin.

1. The alpha 1-adrenoceptor antagonist indoramin is rapidly and extensively absorbed after oral administration, but with only low to moderate bioavailability (8-24% median) from the tablet (Baratol). Although plasma protein binding is high (72-86%), the drug is widely distributed into tissues (with median Vz 6.3-7.7 l/kg after i.v. dosage). 2. Elimination of indoramin is rapid in most healthy volunteers, with median plasma clearances of 18-26 ml/min per kg, after i.v. dosage. Elimination occurs principally by metabolism, the major route being indole 6-hydroxylation, followed by sulphate conjugation of 6-hydroxyindoramin. The faecal route of excretion predominates (45-50% of dose), with a further 35-40% in the urine. 3. Extensive variation in single-dose oral pharmacokinetics of indoramin is due largely to the existence of a poor metabolizer phenotype which co-segregates with that of debrisoquine. 4. On repeated administration (37.5 mg twice daily) to healthy volunteers, plasma concentrations of indoramin accumulate 3-4-fold above those anticipated from single-dose kinetics. However, steady state is achieved within the first week of dosing. 5. The pharmacokinetics of indoramin are substantially altered in the elderly. The oral AUC for a 50 mg dose is increased approx. 5-fold and the t1/2 2.5-fold. 6. Cirrhotic liver disease enhances bioavailability and decreases clearance, approx. 2-fold in each case for single oral and i.v. doses of 50 mg and 0.15 mg/kg respectively. 7. After oral indoramin Cmax and AUC are both raised (58% and 25%, respectively, for a 50 mg dose) by co-ingested ethanol (0.5 g/kg). After i.v. indoramin, kinetics are unaffected by alcohol, but indoramin (0.175 mg/kg) slightly increases (26%) blood ethanol concentrations during the first hour after dosing. 8. The pharmacodynamics of indoramin appear to be related to the combined pharmacokinetics of the drug and its 6-hydroxylated metabolite, which contributes to the antihypertensive effect.

Adrenergic alpha-Antagonists↗

PubMed1985

Investigations into the bradycardic action of indoramin.

Indoramin is a selective alpha 1-antagonist which reduces blood pressure without reflex tachycardia and can cause a bradycardia. The direct bradycardic effect of indoramin was investigated in various isolated cardiac preparations as well as in the intact cat. In isolated guinea-pig atria indoramin reduced spontaneous atrial rate in concentrations similar to those that reduced maximal driving frequency but smaller than those reducing contractility (EC30 = 0.9, 1.3 and 5.2 micrograms/ml, respectively). In the isolated perfused electrically driven (2.5 Hz) guinea-pig heart, indoramin 1 microgram/ml mainly increased ST interval with no effect on QRS interval, higher concentrations (3 micrograms/ml) also increased the QRS interval. In anaesthetized cats indoramin 6 mg/kg i.v. reduced blood pressure and heart rate (increased cycle length), increased the ST interval and effective refractory period (measured by electrical stimuli from the right ventricle) but had little or no effect on the QRS interval and the diastolic stimulation threshold. With the 10 mg/kg dose the latter two parameters were increased. Analogous experiments with the antiarrhythmic drug mexiletine (class I) showed little changes in cycle length, effective refractory period and the ST interval, however, there was a marked increase in diastolic threshold. DL-sotalol, which as well as having a beta-adrenoceptor blocking action, also prolongs action potential duration (class III antiarrhythmic activity), had the same cardiac profile as indoramin. For both indoramin and sotalol a significant positive correlation was shown between increase in cycle length and increase in effective refractory period. It is suggested that indoramin exerts class III antiarrhythmic activity and that this property is responsible for the bradycardic action of the drug which is seen in doses that already markedly reduce blood pressure. In higher doses or concentrations indoramin also exerts class I antiarrhythmic activity which, however, does not contribute to the bradycardic effect.

Animals↗

PubMed2001

A double-blind randomized placebo-controlled trial of oral indoramin to treat chronic anal fissure.

BACKGROUND: Indoramin is an alpha1-adrenoceptor antagonist and has been shown to reduce anal resting pressure. Its therapeutic potential has not been explored. The aim of this study was to determine the outcome of treatment with oral indoramin on patients with chronic anal fissure in the setting of a double-blind randomized placebo-controlled trial. METHODS: Twenty-three patients with chronic anal fissure were computer randomized to receive a 6-week course of oral indoramin (20 mg) or placebo in identical capsules, twice daily and with bulk-forming laxatives. Pain was assessed by a visual analogue scale from 0 to 10. Anal resting pressure, heart rate and blood pressure were recorded. Patients were reviewed 1 h after taking the capsule and at 2, 6 and 12 weeks thereafter. RESULTS: Fourteen patients were randomized to indoramin and 9 to placebo. Maximum anal resting pressure was reduced from a mean of 96.4 cm H2O (+/- 32) to 67.6 cm H2O (+/- 26), 1 h after indoramin (P=0.02) and there was no significant change after placebo. There were no significant changes in heart rate or blood pressure. Pain was reduced in the placebo group from a score of 4.9 to 2.0 after 6 weeks (P < 0.01) but not in the indoramin group. After 6 weeks, healing had occurred in one (7%) patient in the indoramin group and in 2 (22%) in the placebo group (P > 0.1). After 3 months, the chronic anal fissure in the indoramin group had recurred. The trial was terminated early because of poor healing rates. CONCLUSION: An oral dose of indoramin (20 mg) administered twice daily reduced anal resting pressure by 30% compared with pretreatment levels but was ineffective in healing chronic anal fissures.

Clinical Trial↗

PubMed1986

The effect of indoramin on exercise performance in mild hypertension.

The alpha 1-adrenoceptor antagonist indoramin is proposed to reduce arterial blood pressure without a concomitantly significant increase in heart rate (HR). The present study involves assessment of the effect of alpha 1-adrenoceptor antagonism in patients with mild hypertension on the HR/oxygen consumption (Vo2) relationship, which has previously been shown to indicate improvement in cardiorespiratory fitness following exercise training. A total of 16 patients with a systolic blood pressure of 140-200 mm Hg and diastolic blood pressure of 95-110 mm Hg were examined. A double-blind, placebo-controlled study design was utilized. Following initial observations, the patients were randomized into one group (a) of seven patients who were given a placebo, indoramin, and finally placebo, and a second group (b) of nine patients who were given the two agents in the reverse order, i.e., indoramin, placebo, indoramin; each intervention lasted for 2 weeks and indoramin was given in a dose of 75 mg/day. Indoramin caused a reduction in the elevation of the computed regression line relating HR to Vo2 (a shift to the right), such that at the same HR a greater Vo2 was attained in 11 of the 16 patients in comparison with the baseline exercise test. Pooled results showed a shift of the HR/Vo2 regression line to the right when indoramin was compared with baseline (p less than 0.05) or placebo. In the same patients, indoramin caused a decrease in arterial blood pressure during exercise relative to baseline or placebo periods, and a decrease in the HR during exercise relative to baseline period, but not when compared with placebo periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗

PubMed1989

Pharmacokinetic interaction between indoramin and ethanol.

1. The effect of ethanol consumption (0.5 g/kg) on the pharmacokinetics of the alpha adrenoceptor antagonist indoramin, administered orally (50 mg) or intravenously (0.175 mg/kg) has been investigated in young volunteers. Sedation was also assessed using a visual analogue scale. 2. After oral indoramin administration, ethanol caused increases of 58% (P less than 0.01) in Cpmax, and 25% (P less than 0.05) in AUC. There was no effect of alcohol on elimination half-life. The combination of ethanol and indoramin was more sedative than indoramin alone. 3. Ethanol did not alter the pharmacokinetics of an intravenous dose of indoramin. However indoramin caused a small but statistically significant increase (26%) in blood ethanol concentrations during the first 1.25 h after dosing. Both indoramin and ethanol caused sedation. 4. The increased bioavailability of oral indoramin in the presence of ethanol may reflect some enhanced absorption, but it is also consistent with inhibition of first-pass metabolism of a flow-limited drug. The clinical implications are discussed.

Administration, Oral↗

PubMedDate not supplied

Investigation into mechanism of lack of reflex tachycardia in response to hypotensive action of indoramin in dogs.

In animals and man, the selective alpha 1-adrenoceptor antagonist indoramin reduces arterial pressure without increasing heart rate. We studied this mechanism of absence of reflex tachycardia in anaesthetised dogs. Indoramin reduced (p less than 0.05) arterial pressure with no reflex increase in heart rate, whereas phenoxybenzamine reduced (p less than 0.05) pressure but increased (p less than 0.05) heart rate. Atropine and propranolol pretreatment, vagotomy and division of the cardio-accelerator nerve did not prevent the reduction (p less than 0.05) in arterial pressure and heart rate seen with indoramin. Mexiletine, a drug which has membrane-stabilising activity, had no effect on heart rate or arterial pressure. Mexiletine and indoramin did not affect the increases in heart rate produced by stimulation of the cardio-accelerator nerve. Indoramin reduced (p less than 0.05) the increases in heart rate and arterial pressure produced by bilateral carotid occlusion, and potentiated the arterial pressure reduction but attenuated the heart rate response to intravenous isoprenaline. It also reduced (nonsignificantly) the responses to intravenous noradrenaline and phenylethylamine but had no effect on the arterial pressure and heart rate responses to bilateral central vagal stimulation. We conclude that the absence of the reflex tachycardia with hypotensive doses of indoramin does not result from the myocardial membrane-stabilising action of indoramin or from alteration in sympathetic and parasympathetic activity, but may occur partly from a reduction in baroreceptor sensitivity.

Animals↗

PubMed1990

Antiarrhythmic and metabolic effects of indoramin during acute regional ischemia and reperfusion in isolated rat heart.

The antiarrhythmic effect of alpha 1-adrenoceptor antagonists during myocardial ischemia and reperfusion remains controversial. The potential antiarrhythmic properties of indoramin, an alpha 1-antagonist, were assessed in the isolated perfused rat heart during regional ischemia and during sustained reperfusion. Coronary artery ligation (CAL) decreased the ventricular fibrillation threshold (VFT) of control hearts from 9.1 +/- 1.3 (pre-CAL, mean +/- SEM) to 2.1 +/- 0.5 mA 15 min post-CAL (p less than 0.0001). Perfusion with indoramin 10(-8) M (alpha 1-receptor antagonistic concentration) started 5 min prior to CAL did not prevent the fall in VFT after CAL. Indoramin 10(-6) M prevented the fall in VFT after CAL relative to the control group. Indoramin 10(-5) M markedly increased the VFT before CAL from 9.9 +/- 1.0 to 28.6 +/- 2.9 mA (p less than 0.0001) and prevented the fall in VFT after CAL. During reperfusion, indoramin 10(-5) M decreased the incidence of spontaneous ventricular fibrillation (VF) to 1 of 6 vs. 6 of 6 in the control group (p less than 0.02). Indoramin 10(-5) M preserved adenosine triphosphate in the reperfused myocardium: 2.82 +/- 0.06 vs. 2.16 +/- 0.21 mumol/g in the control group (p less than 0.05). Specific alpha 1-antagonist properties of indoramin did not appear to be involved in the antiarrhythmic effects.

Animals↗

PubMed1984

Differential blockade of alpha-adrenoceptors by indoramin.

The effect of equihypotensive single oral doses of indoramin (mean dose 67 mg), phenoxybenzamine (mean dose 50 mg), hydralazine (mean dose 133 mg) and placebo on arterial pressure and heart rate in the supine and standing position was studied in six normal volunteers. Observations were made before and at 2 and 4 h after drug administration. Plasma noradrenaline (NA) was measured at each time interval in the supine position, and after 4 min of standing. Plasma renin activity (PRA) was measured at each time interval after 30 min in the standing position. The three active drugs reduced systolic arterial pressure in the standing position to a similar extent (indoramin, -24 mm Hg; phenoxybenzamine, -23.4 mm Hg; hydralazine, -30.4 mm Hg). The maximum effect of indoramin and phenoxybenzamine was observed at 4 h, and of hydralazine at 2 h after drug administration. The reductions of arterial pressure in the standing position were accompanied by increases in heart rate, plasma NA and PRA. Small increases were observed after indoramin (heart rate, + 9.2 beats min-1; plasma NA, + 126 pg/ml; PRA, + 0.33 ng angiotensin 1 ml-1 h-1), greater increases after phenoxybenzamine (heart rate, + 20; plasma NA, + 210; PRA, + 0.47), and the greatest increases after hydralazine (heart rate, + 26; plasma NA, + 250; PRA, + 1.16). In the supine position, indoramin and phenoxybenzamine produced no effect on arterial pressure, heart rate or plasma NA. Hydralazine produced small reductions in diastolic pressure, which were accompanied by an increase in heart rate of 25.5 beats min-1 (P less than 0.01 when compared to placebo) and in plasma NA of 223 pg ml-1 (P less than 0.05). Plasma NA, PRA and heart rate increased together and may be regarded as three interdependent indices of sympathetic activity. Indoramin reduced the degree of increase of plasma NA, PRA and heart rate per unit fall in pressure, when compared to phenoxybenzamine and hydralazine. The effect of phenoxybenzamine and hydralazine on the degree of increase was similar. The results are consistent with the hypothesis that indoramin produces selective postsynaptic alpha 1-adrenoceptor blockade in man, and therefore produces relatively less tachycardia and NA increase than does a non-selective alpha-adrenoceptor antagonist (phenoxybenzamine) or an arteriolar vasodilator (hydralazine).

Adolescent↗

PubMed1984

Pharmacokinetics of oral indoramin in elderly and middle-aged female volunteers.

Indoramin was administered as a single 50 mg oral tablet to 5 elderly (aged 68-71 years) and 6 middle-aged (aged 46-55 years) healthy female volunteers. The mean half life of indoramin in elderly subjects (14.7 +/- 4.8 h, mean +/- SEM) was statistically significantly longer than that seen in middle-aged subjects (5.1 +/- 1.0 h). The mean plasma concentrations of indoramin and mean area under the plasma concentration/time curve were also greater in elderly than in middle-aged subjects, although this did not achieve statistical significance. In many elderly patients, therefore, a reduction in dosage may be required due to the apparent reduction in clearance of indoramin. However, because of the wide inter-subject variability observed in the oral pharmacokinetics of indoramin, individual titration of indoramin dosage in all patients may be desirable.

Administration, Oral↗

PubMed1985

The cardiovascular effects of centrally and peripherally administered indoramin in conscious rats.

Indoramin has centrally mediated hypotensive effects in anesthetized animals. In the present study, the cardiovascular effect of central and peripheral indoramin was determined in conscious, freely moving rats. Animals were instrumented with femoral arterial and venous catheters and miniaturized pulsed-Doppler flow probes were placed on the superior mesenteric and renal arteries and lower abdominal aorta. Injection of indoramin (25-100 micrograms) in the lateral cerebroventricle produced an immediate (1.5 min) increase in arterial pressure which was accompanied by vasoconstriction in all three vascular beds. By 10 min all values had returned to control except for heart rate which was decreased. Vehicle alone or intravenous indoramin (100 micrograms) had no effect. In baroreceptor-denervated rats smaller effects were seen. Intravenous indoramin (3.0-13.5 mg/kg) produced dose-related decreases in arterial pressure, heart rate, and hindquarter vascular resistance. The 13.5 mg/kg dose blocked to a similar degree the cardiovascular effect produced by intravenous norepinephrine or stimulation of the paraventricular nucleus. These data suggest that indoramin is an effective peripheral alpha-adrenergic receptor antagonist but does not appear to be centrally active as a hypotensive agent.

Animals↗

PubMed1986

Recent developments in the pharmacology and pharmacokinetics of indoramin.

Some recent studies complementing earlier reports on the pharmacology and pharmacokinetics of indoramin are briefly reviewed. Competitive blockade of peripheral postsynaptic alpha 1-adrenoceptors is confirmed as the primary mechanism for the antihypertensive activity of indoramin. Various reasons have been proposed to explain the absence of reflex tachycardia when blood pressure is reduced by indoramin. These have included myocardial membrane stabilization and selectivity for alpha 1-adrenoceptors. More recently, class III antiarrhythmic activity and a reduction in baroreceptor sensitivity have also been proposed, and several animal studies have indicated that a central cardioregulatory mechanism contributes to the lack of reflex tachycardia. Chronic dosing with indoramin in hypercholesterolemic monkeys significantly raises high-density lipoprotein cholesterol levels. Recent pharmacokinetic and biotransformation studies confirm earlier reports that the drug is well absorbed and extensively metabolized and has a plasma half-life of approximately 5 h. This is increased in the elderly. 6-Hydroxyindoramin is a major metabolite; it is pharmacologically very similar to indoramin itself, except that it penetrates the central nervous system less readily. Plasma levels of this metabolite are about one-third those of indoramin during chronic twice-daily dosing. Its formation is not expected to have any undesirable clinical consequences.

Administration, Oral↗

PubMed1986

The acute and chronic effects of indoramin on renal function, hemodynamics, and transport.

The acute and chronic renal effects of indoramin, an alpha 1-adrenoceptor antagonist, were investigated in six normotensive men (mean +/- SEM age, 36 +/- 3 years). Renal clearance studies were done during steady-state water diuresis before administration of indoramin (baseline), 3-4 h after a single 50-mg oral dose (acute study), and after 7 days of treatment with 25 mg twice daily (chronic study). After a single 50-mg oral dose, mean supine blood pressure decreased from 117/76 mm Hg at baseline to 109/74 mm Hg (NS), and glomerular filtration rate and renal blood flow were unchanged. There were small decreases (0.05 less than p less than 0.1) in the fractional excretion of sodium and potassium. After chronic administration (7 days) of indoramin, no significant changes in blood pressure, renal function, renal hemodynamics, or fluid and electrolyte excretion were observed. Mean body weight tended to decrease and fractional sodium excretion increased slightly (NS) after 7 days of indoramin. Plasma renin and aldosterone concentrations tended to increase (NS) after chronic indoramin administration. The results of this study indicate that acute and chronic administration of indoramin does not adversely affect renal function, renal hemodynamics, or fluid and electrolyte excretion in normotensive subjects.

Administration, Oral↗