Perindopril + indapamide: new preparation. Simple trick

(1) The combination of perindopril 4 mg + indapamide 1.25 mg is approved for second-line treatment of hypertension after failure of perindopril alone. (2) The other combination, of a low dose of an angiotensin-converting-enzyme inhibitor (2 mg of perindopril) and a diuretic (0.625 mg of indapamide), is being promoted as first-line treatment of hypertension. (3) The clinical files for both preparations are limited to the strict minimum. (4) A dose-finding study showed that the perindopril 4 mg + indapamide 1.25 mg dose combination offered the best risk-benefit ratio by comparison with combinations containing the same perindopril dose but other indapamide doses. (5) A double-blind trial suggests that the antihypertensive activity of the perindopril 4 mg + indapamide 1.25 mg combination is equivalent to that of the captopril 50 mg + hydrochlorothiazide 25 mg and enalapril 20 mg + hydrochlorothiazide 12.5 mg combinations. The safety profile was the same for the three combinations. (6) The 2-mg perindopril combination has not been compared with perindopril monotherapy at the usual dose of 4 mg, or with indapamide monotherapy at a mean dose of 2.5 mg. (7) The two combinations are costlier than their competitors.     

Natriuretic and diuretic effects of cicletanine in conscious,hydrated, normotensive rats

The natriuretic and diuretic actions of cicletanine, a novel agent with vasorelaxant and antihypertensive properties, were examined in conscious, hydrated, normotensive rats. Cicletanine, the (+)- and (?)-enantiomers of cicletanine, hydrochlorothiazide (HCTZ), or vehicle(s) were administered orally or intravenously (1, 3, 10, 30 mg base/kg) to water-loaded (27 ml/kg) rats and 3 hr urine volume, Na⁺ and K⁺ were measured. Racemic cicletanine (3 mg/Kg, p.o.) caused a significant increase in urinary Na⁺(+174%) and K⁺ (+46%) excretion, unaccompanied by diuresis. Diuresis was detected only with larger oral doses of racemic cicletanine (10–30 mg/kg). Oral administration of a 1-mg/kg dose of (+)-cicletanine caused significant natriuresis that was not detected with either racemic or (?)-cicletanine. The (+)-enantiomer (3–30 mg/kg) produced natriuresis and diuresis quantitatively similar to that of racemic cicletanine. By contrast, (?)-cicletanine induced only slight natriuresis, kaliuresis, and diuresis upon administration of the largest dose (30 mg/kg, p.o.). Intravenous administration of the racemate and enantiomers of cicletanine caused natriuretic/diuretic activity that was very similar to that seen with oral administration. The natriuresis caused by a 3-mg/kg dose of racemic cicletanine was unaffected by indomethacin. However, indomethacin attenuated the natriuresis and eliminated the diuresis produced by the 10- and 30-mg/kg doses of cicletanine. Indomethacin had no effect on the kaliuretic actions of cicletanine. Indomethacin blunted the natriuresis and eliminated the diuresis caused by all doses of HCTZ. In conclusion, the natriuretic, kaliuretic, and diuretic effects of racemic cicletanine in the conscious, hydrated, normotensive rat appear to be mediated primarily by the ( + )-enantiomer. A dose-dependent separation exists between the natriuretic and diuretic actions of cicletanine, with only natriuresis noted at smaller doses. The natriuresis caused by racemic cicletanine has both indomethacin-resistant and indomethacin-sensitive components, while cicletanine-induced diuresis appears to be mediated exclusively by prostaglandins.     

Indapamide sustained release: a review of its use in the treatment of hypertension

A low-dose sustained-release (SR) formulation of the thiazide-type diuretic indapamide, indapamide SR (Natrilix SR), retains the antihypertensive activity of the immediate-release (IR) formulation, with a smoother pharmacokinetic profile. In well controlled 12- to 52-week clinical trials, indapamide SR 1.5 mg/day was well tolerated and reduced blood pressure as effectively as therapeutic dosages of amlodipine, candesartan, enalapril, hydrochlorothiazide or indapamide IR. Indapamide SR was also more effective than enalapril in reducing left ventricular hypertrophy (LVH), and similar reductions in renal end-organ damage, assessed by microalbuminuria, were seen with indapamide SR- and enalapril-based antihypertensive strategies. Indapamide SR provides an effective option for initial antihypertensive monotherapy and a basis for multidrug antihypertensive strategies.     

Antihypertensive property of a novel uricosuric diuretic,S-8666, in rats

The antihypertensive, diuretic, and toxicological effects of S-8666 were studied in rats. At doses of more than 60 mg/kg/day, p.o., S-8666 was antihypertensive in DOCA-salt hypertensive rats with a potency corresponding to 1/20 of that of trichlormethiazide. The antihypertensive effect was dose-dependent, and, at the higher doses, S-8666 had a more potent depressor effect than trichlormethiazide. The antihypertensive activity of S-8666 was shown predominantly by the S-(?)-enantiomer, with the R-(+)-enantiomer being only slightly active. A similar dose-dependent antihypertensive effect was shown by furosemide, tienilic acid, or indacrinone, but the therapeutic index (LD₅₀/minimum effective dose) of S-8666 was the highest among them. The acute diuretic and natriuretic effects of S-8666 after oral administration of 60–200 mg/kg to DOCA-salt hypertensive rats correlated well with its antihypertensive effect, although such diuretic and natriuretic effects in normotensive rats had no effect on blood pressure. S-8666, like trichlormethiazide, showed a prophylactic effect on the development of hypertension in DOCA-salt hypertensive rats, salt-loaded spontaneously hypertensive rats (SHR), and salt-loaded Dahl-S rats, though it was much less potent. Moreover, the combination of S-8666 with captopril in SHR enhanced the depressor effect of captopril like hydrochlorothiazide. These results indicate that S-8666 can be an effective nonthiazide diuretic for use as an antihypertensive agent.     

STUDIES ON INTERACTION OF TIMOLOL, HYDROCHLOROTHIAZIDE AND AMILORIDE IN THE RAT

1. The acute effects of hydrochlorothiazide, amiloride, timolol and their combinations on diuresis and arterial pressure were studied in rats. 2. Timolol did not modify the diuretic and saluretic effects of hydrochlorothiazide and/or amiloride and had no diuretic or antidiuretic effects alone. 3. At a single dose of 1 25 mg/kg, p.o., timolol alone had no antihypertensive effect in spontaneously hypertensive rats. 4. The antihypertensive effect of hydrochlorothiazide + amiloride+timolol was significantly greater than with any of the drugs alone.     

Defect of the potassium transport process in the kidney of spontaneously hypertensive rats.

We investigated the natriuretic and kaliuretic effect of distal tubular diuretics in saline-loaded spontaneously hypertensive Wistar rats (SHR) from three different sources and normotensive Wistar rats (NWR). Orally administered early distal tubular diuretics (hydrochlorothiazide, chlorthalidone, metolazone, indapamide and cicletanine) caused much less potassium excretion in SHR than in NWR, whereas the magnitude of concurrent natriuresis was similar in both NWR and SHR. The intriguing renal handling of potassium excretion was exemplified by hydrochlorothiazide, for which enhanced kaliuresis was dose dependent in NWR but not in SHR. The doses tested ranged from 1 to 100 mg/kg, p.o. Amiloride, a late distal tubular diuretic, was also evaluated for its effect on sodium and potassium excretion in NWR and SHR. Amiloride produced potassium retention more effectively in NWR than in SHR, although the magnitude of natriuresis was similar. The difference between SHR and NWR with regard to potassium-retaining activity of amiloride was consistent at all doses tested (1-30 mg/kg, p.o.). In conclusion, it was suggested that SHR appear to have a genetic defect in potassium transport in the distal nephron.     

Antihypertensive effect of indapamide given in conjunction with captopril in severe hypertension

The efficacy of captopril alone or in combination with indapamide was evaluated in 17 patients with severe hypertension (diastolic greater than 120 mmHg) previously treated with triple antihypertensive therapy, i.e. diuretic, beta-blocker and a vasodilator. After a wash-out period of 1 week, captopril was given initially as 75 mg/day for 2 weeks; at the end of this period, the dosage was doubled to 150 mg/day and continued at this level for a further 2 weeks. Indapamide (2.5 mg/day) was then added to the regimen and administered for 1 month. The results showed that captopril alone lowered, but did not normalize the blood pressure. The mean diastolic pressure was reduced to 117 and 103.8 mmHg after dosages of captopril of 75 mg and 150 mg, respectively. On the addition of indapamide, the blood pressure was normalized to 93.82 mmHg mean diastolic pressure. Systolic readings were similarly reduced. Two patients developed skin rashes while on captopril alone: no other treatment-related side-effects were reported once indapamide therapy had commenced.     

Protective effects of delapril combined with indapamide or hydrochlorothiazide in spontaneously hypertensive stroke-prone rats: a comparative dose-response analysis

In previous articles, we have shown that the combination of the angiotensin-converting enzyme (ACE) inhibitor delapril (12 mg/kg/day) and the diuretic indapamide (1 mg/kg/ day) was able to prolong the life span significantly in salt-loaded stroke-prone spontaneously hypertensive rats (SHRsp). Because this finding was partly dependent on the antagonism of salt-loading effects by pharmacologic induction of diuresis, which prevented any increase in blood pressure values, we decided to evaluate whether lower doses of the combination could be equally protective without changing the progression of hypertension. Thus, we studied several treatments with progressively lower doses of delapril (6, 3, or 1.5 mg/kg/day) combined with indapamide (0.5, 0.25, or 0.125 mg/kg/day) or hydrochlorothiazide (2.5, 1.25, or 0.625 mg/kg/day) in salt-loaded SHRsp. Salt-loaded untreated animals were considered to be the control group. In agreement with previous experiments, control rats reached 50% mortality approximately 7 weeks after the beginning of salt loading. The combination of delapril and hydrochlorothiazide at the two lowest doses was not able to delay animal death significantly, whereas treatment with delapril and indapamide at the lowest dose was effective (50% survival rate, 15 weeks). The groups treated with the highest dose of delapril and hydrochlorothiazide or with the intermediate or highest dose of delapril and indapamide did not reach 50% mortality by the end of the experiment, at 44 weeks of treatment (i.e., when animals reached age 1 year). Only the highest delapril and indapamide doses were able to increase diuresis, but for a relatively short period. None of the treatments was able to lower or control blood pressure levels adequately. Therefore, blood pressure levels by themselves were not predictive of rat mortality. In contrast, the maximal value of proteinuria in the weeks preceding death was inversely correlated with the survival time. In conclusion, this study shows that low doses of an ACE inhibitor in combination with a diuretic can be effectively protective in a model of severe hypertension, independent of any change in blood pressure levels.     

Antihypertensive effect of indapamide given in conjunction with captopril in severe hypertension

Summary

The efficacy of captopril alone or in combination with indapamide was evaluated in 17 patients with severe hypertension (diastolic > 120 mmHg) previously treated with triple antihypertensive therapy, i.e. diuretic, beta-blocker and a vasodilator. After a wash-out period of 1 week, captopril was given initially as 75?mg/day for 2 weeks; at the end of this period, the dosage was doubled to 150?mg/day and continued at this level for a further 2 weeks. Indapamide (2.5?mg/day) was then added to the regimen and administered for 1 month. The results showed that captopril alone lowered, but did not normalize the blood pressure. The mean diastolic pressure was reduced to 117 and 103.8 mmHg after dosages of captopril of 75?mg and 150?mg, respectively. On the addition of indapamide, the blood pressure was normalized to 93.82 mmHg mean diastolic pressure. Systolic readings were similarly reduced. Two patients developed skin rashes while on captopril alone: no other treatment-related side-effects were reported once indapamide therapy had commenced.     

Effects of indapamide in rats with pressure overload left ventricular hypertrophy

We studied the in vivo effects of the antihypertensive diuretic agent indapamide on left ventricular (LV) morphology in chronically pressure-overloaded rat hearts. LV pressure and subsequently LV mass were increased by banding the ascending aorta over a period of 6 weeks. Thereafter, animals were treated with low-dose (1 mg/kg/day, n = 9) or high-dose (10 mg/kg/day, n = 9) indapamide for another 6 weeks. Low-dose indapamide treatment reduced LV weights as compared with vehicle-treated controls (n = 9; -12%; p = 0.008). Furthermore, low-dose indapamide treatment resulted in a decrease of myocyte volume (59.0 +/- 10.6 vs. 79.0 +/- 9.8 m3 x 10(-27); p < 0.05) and an improvement of molecular markers of hypertrophy: a reduction of LV atrial natriuretic factor mRNA expression (-37%; p < 0.05), and an increase of the V1/V3 myosin ratio (+121%; p < 0.05). Low-dose indapamide also reduced significantly plasma (-65%) and LV angiotensin-converting enzyme (ACE) activities (-74%) as well as LV mRNA levels (-24%). These changes were observed despite continued pressure overload of the LV and despite a lack of significant changes in sodium excretion with the prolonged administration of low-dose indapamide. High-dose indapamide treatment showed no significant effects on LV mass, structure, and gene expression. Furthermore, high-dose indapamide increased plasma renin activity substantially, whereas low-dose treatment was without effect on circulating renin. In conclusion, in rats with continuous LV pressure-overload low-dose treatment with indapamide leads to mild regression of cardiac hypertrophy, accompanied by a downregulation of components of the cardiac renin-angiotensin system. These effects may be mediated by mechanisms apart from the known diuretic and antihypertensive actions of indapamide, because sodium excretion and blood pressure were stable with long-term treatment and are unlikely to be related to LVH regression in this model.     

In vitro and ex vivo inhibition of the modification of low-density lipoprotein by indapamide.

The effect of an antihypertensive drug, indapamide, on copper- and endothelial cell-induced peroxidation of human low-density lipoprotein (LDL) was studied and compared with that of drugs previously shown to protect LDL against peroxidation: probucol and vitamin E and other thiazidic and nonthiazidic diuretics (clopamide, hydrochlorothiazide, and furosemide). Incubation with indapamide inhibited in a dose-dependent manner LDL peroxidation induced either by copper ions or by cultured endothelial cells. Both electrophoretic mobility and thiobarbituric acid-reactive substances (TBARS) content of LDL returned to almost normal values in the presence of 1 microM indapamide. This drug was at least 10 times more potent than probucol and vitamin E in inhibiting LDL peroxidation. No inhibitory effect has been observed with clopamide, hydrochlorothiazide, and furosemide in the same experimental conditions. Homozygote Watanabe rabbits were treated orally with indapamide (10 mg/kg/d for 3 days) to evaluate the potential protective effect of the compound on LDL peroxidation in vivo. Purified LDL from placebo and treated rabbits were submitted to peroxidation induced by copper ions, and indapamide was effectively able to protect LDL in these experimental conditions. This effect was especially obvious 6 and 8 h after the start of the incubation when LDL of the placebo-treated animals were modified. The mechanism of action of these drugs was examined in vitro using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) test and in kinetic studies of arachidonic acid photoperoxidation. Indapamide as well as vitamin E and probucol were effective free radical scavengers, but the other diuretic molecules were not.(ABSTRACT TRUNCATED AT 250 WORDS)     

ANGIOTENSIN-CONVERTING ENZYME INHIBITION AS FIRST-LINE TREATMENT FOR HYPERTENSION

1. Perindopril (4 mg) was compared with atenolol (50 mg), captopril (25 mg b. d.) or a diuretic (hydrochlorothiazide 50 mg and amiloride 5 mg) in three studies involving a total of 503 hypertensive patients with a diastolic blood pressure (DBP) of 95–125 mmHg.
2. A 4 week single-blind placebo period preceded 12 weeks of active treatment. Dose titration was at weeks 4 and 8 if supine DBP >90 mmHg. The dose was doubled and if necessary a diuretic was added in the atenolol or captopril comparisons, and atenolol was added in the diuretic study.
3. The fall in supine blood pressure (BP) was 27/17 mmHg with perindopril and 21/16 mmHg for atenolol. Monotherapy controlled 55% of patients on perindopril and 48% on atenolol, increasing to 78% and 58% with the addition of hydrochlorothiazide, respectively. Captopril caused a BP fall of 19/12 mmHg compared with 27/18 mmHg for perindopril, with 49% of both groups being controlled on monotherapy.
4. Diuretic addition produced a greater antihypertensive effect with perindopril (75%) compared with 57% for captopril in achieving control. Perindopril caused a comparable fall in supine BP to the diuretic combination 27/19 mmHg and 31/18 mmHg, but the fall in erect systolic BP was significantly greater for the diuretic. At 3 months, 85% of the diuretic group and 78% of the perindopril group achieved the target BP.
5. A multicentre trial of 856 patients treated with perindopril (690 patients treated for 1 year or more) has shown that BP control is maintained in the long term with a low incidence of side-effects (7.9%) causing withdrawal from treatment. These studies demonstrate that perindopril compares favourably with standard first-line therapy for mild to moderate hypertension.     

Functional arterial baroreflex attenuates the effects of antihypertensive drugs in conscious rats

The present work was designed to observe the influences of arterial baroreflex (ABR) function on cardiovascular effects produced by four routinely used antihypertensive drugs in conscious rats. A low ABR model was obtained by the performance of sinoaortic denervation (SAD). The doses of the four drugs were as follows: nifedipine (1.5, 3.0 mg/kg), captopril (50, 100 mg/kg), atenolol (10, 20 mg/kg), and hydrochlorothiazide (20, 40 mg/kg). They were administered via an intra-gastric catheter. Compared with sham-operated rats, SAD significantly increased blood pressure variability about 2 times without modification of blood pressure level. The decrease in blood pressure level induced by the four tested drugs was larger in SAD rats than in sham-operated rats, which decreased to about 10 mmHg. Pulse interval was not changed by the treatment of captopril, but prolonged by atenolol in both sham-operated and SAD rats. In sham-operated groups, treatment of both nifedipine and hydrochlorothiazide decreased pulse interval. Whereas in sinoaortic denervated ones, this tachycardia was prevented. Among the four tested drugs, it was found that only nifedipine and atenolol significantly decreased blood pressure variability in SAD rats. It can be concluded that arterial baroreflex function was able to attenuate the hypotensive effects produced by antihypertensive drugs in conscious rats.     

Chronic antihypertensive effects of captopril (SQ 14,225), an orally active angiotensin I-converting enzyme inhibitor, in conscious 2-kidney renal hypertensive rats.

Indirect systolic blood pressure (SBP) was monitored in 9 groups of 15 male conscious 2-kidney renal hypertensive rats (RHR) for over 6 months. Daily oral dosing with captopril (SQ 14,225, D-3-mercapto-2-methylpropanoyl-L-proline, 30 mg/kg), an orally active angiotensin I-converting enzyme inhibitor, lowered SBP 30--50 MM Hg during this period. Withdrawal of captopril for 5 days at 1, 3 and 6 months resulted in gradual return of SBP to control levels without overshoot. Resumption of dosage with captopril again decreased SBP. Daily oral dosing with hydrochlorothiazide (HCTZ, 6 mg/kg/day) alone for 6 months had little or no effect on SBP, but increased the antihypertensive effect of captopril. Daily oral dosing with hydralazine (6 mg/kg) caused an initial marked antihypertensive effect greater than that of captopril but almost complete tolerance developed within 4 weeks of dosing. Highest survival rates occurred in RHR treated with captopril plus HCTZ. In four other similarly treated groups of RHR and normotensive rats (NR), least cardiac hypertrophy and highest plasma renin activity occurred in captopril-treated animals compared with vehicle-treated controls. Plasma renin activity was about 2 to 4 fold higher in the rats dosed with captopril compared with vehicle-treated rats. Heart weight/body weight ratios, initially higher in the two RHR groups compared to NR, decreased only in the captopril treated group to or near those of the NR groups. These results indicate that chronic treatment with captopril decreased SBP and cardiac weights of RHR, and that HCTZ, or possibly other diuretics, can augment the antihypertensive effect of captopril while having little or no effect by themselves.     

Acute blood pressure and urinary responses to single dose combinations of captopril and diuretics in conscious spontaneously hypertensive rats

The present studies involved oral administration of captopril alone or in combination with individual diuretics in conscious, freely-moving spontaneously hypertensive rats (SHR). Both blood pressure (BP) and urinary fluid and electrolyte excretion were concomitantly measured. Captopril, 10 mg kg-1, caused a decrease in BP (-18 +/- 3 mm Hg) which was not significantly different from control (-10 +/- 2 mm Hg). Diuretics alone also failed to alter BP. However the BP-lowering effect of captopril was readily potentiated by concomitant administration of a single oral dose of frusemide (10 and 30 mg kg-1) in proportion to the magnitude of urinary loss. Hydrochlorothiazide at 1 and 3 mg kg-1 oral and metolazone at 0.3 and 1 mg kg-1 oral induced fluid loss similar to frusemide at 10 mg kg-1 and all produced comparable BP reduction in combination with captopril (25-32 mm Hg). Triamterene did not increase fluid excretion and was ineffective. In SHR with bilateral ureteral ligation, the synergistic effect of frusemide was abolished while that of hydrochlorothiazide still occurred with a delayed onset. It is concluded that concomitant measurement of BP and urinary excretion in conscious, freely-moving SHR is a useful technique for studying new antihypertensive drugs. Using this preparation it was found that enhancement of the acute hypotensive response to captopril with concomitant diuretic therapy occurs within 10 min and is primarily related to the fluid and Na loss, regardless of the diuretic agent used.     

Haemodynamic changes in peripheral arterial circulation during antihypertensive treatment with captopril, methyldopa and indapamide

Structural changes in resistance vessels of the lower limbs have been detected in early stages of arterial hypertension. In these patients it might be important to reduce blood pressure by drugs which do not impair peripheral blood flow. Twenty-four patients with arterial hypertension, without target organ damage were randomly given a placebo, 50 mg captopril, 500 mg methyldopa or 2.5 mg indapamide and their blood pressure, arterial blood flow and peripheral resistance were measured at baseline and at the peak action of the antihypertensive treatment. Significant decreases in blood pressure and peripheral resistance have been induced by a single oral dose of captopril and methyldopa: a concomitant significant increase in peripheral blood flow to the lower limbs was also observed during methyldopa treatment. No acute effect was observed on the placebo or on indapamide: the latter induced a decrease in blood pressure and in peripheral resistance along with an increase in arterial blood flow during long-term treatment after four weeks of therapy. Our observations seem to support the usefulness in hypertensive patients with concomitant lesions in the peripheral arterial tree of antihypertensive agents such as methyldopa and indapamide which increase blood flow and reduce peripheral resistance while lowering high blood pressure.     

Indapamide: Clinical Pharmacology,Therapeutic Efficacy in Hypertension,and Adverse Effects

Indapamide will soon be marketed in the United States as an oral antihypertensive agent and diuretic. Its molecular structure includes both a polar sulfamoyl chlorobenzamide moiety and a lipid-soluble methylindoline molety. It differs chemically from the thiazides in that it does not possess the thiazide ring system and it contains only one sulfonamide group. Indapamide is rapidly and well absorbed after oral Ingestion, and it has a long terminal half-life in whole blood which permits once daily administration. Indapamide is extensively metabolized by the liver with excretion of unchanged drug accounting for approximately 5% of the total dose. Although indapamide is thought to exert its antihypertensive effect by its diuretic action, several investigations employing laboratory animal preparations have documented a direct vascular action. It has been categorized as a calcium channel blocking agent and this may account for a portion of its antihypertensive effectiveness. In both the treatment of edema and as an antihypertensive agent, indapamide appears to be comparable to hydrochlorothiazide, chlorthalidone and furosemide and seems to have no clinically important advantage over these agents. Side effects associated with indapamide are minimal and appear to be comparable to those observed with other antihypertensive diuretics. Based on few published studies, indapamide appears to be a useful long acting antihypertensive and diuretic agent that is well tolerated and associated with minimal biochemical abnormalities or side effects.     

Delapril plus indapamide: a review of the combination in the treatment of hypertension

Although many data indicate that the management of hypertension has improved over the last two decades, there is still a large proportion of hypertensive individuals who do not receive adequate management of their blood pressure (BP). Combination therapy with two or more antihypertensive agents from different drug classes is increasingly being recognised as the most effective means of achieving target BP values by pharmacological means, particularly in the large number of patients in whom monotherapy proves to be ineffective. Use of an angiotensin-converting enzyme (ACE) inhibitor combined with a diuretic is a well established antihypertensive combination that is very effective because of the different, yet synergistic, mechanisms of actions of agents from these two drug classes. Delapril is a potent antihypertensive ACE inhibitor, and indapamide is a thiazide-like diuretic with additional antihypertensive properties. The combination of delapril and indapamide provides renoprotective effects, and indapamide is also cardioprotective. Use of these two drugs together is therefore a rational selection for combination therapy, and one that has consistently demonstrated lowering of BP to target values with a level of efficacy that is at least as good as other combinations of ACE inhibitors and diuretics. This combination has also been found to provide favourable effects on haemodynamic parameters, including left ventricular mass index and ejection fraction. Furthermore, combining an ACE inhibitor and a thiazide-type diuretic has been associated with a decreased risk of stroke and is recommended for patients with cerebrovascular disease, a setting in which the combination of delapril and indapamide has therapeutic potential. Because of the additive mechanisms of delapril and indapamide, the dose required for an effective antihypertensive effect is relatively low, and the combination is well tolerated at such doses. In particular, metabolic effects normally associated with diuretics are rare at the therapeutic dose of indapamide used in combination with delapril, making the combination suitable for patients with metabolic disorders in whom diuretic therapy would otherwise not be recommended. Delapril 30 mg and indapamide 2.5mg have been combined in a fixed combination, offering the convenience of a one-tablet-per-day antihypertensive drug regimen for most patients, which, along with good tolerability, helps to address the issue of noncompliance.     

Studies of the antihypertensive effects of CL 242,817, a new angiotensin-I converting enzyme inhibitor [S−(R*, s*)]-1-[(3-acetylthio)-3-benzoyl-2-methyl propionyl-L-proline]

The antihypertensive activity of CL 242, 817 and captopril were evaluated in conscious, unrestrained aorta-coarcted hypertensive rats (AHR); spontaneously hypertensive rats (SHR); and in the two-kidney, one-clip, Goldblatt renal hypertensive beagle (RH2 dog). In AHR, equimolar oral doses of CL 242,817 (5 mg/kg) and captopril (3 mg/kg) had rapid onsets of action and relatively long durations of action. CL 242,817 was significantly more potent and longer-acting than captopril. In the SHR, CL 242,817 was effective in lowering blood pressure by oral, intravenous, or intraperitoneal routes of administration, although less effectively than in AHR. In RH2 dogs, pretreated with the diuretic quinethazone, CL 242,817 (20 mg/kg, p.o.) lowered blood pressure more effectively than an equimolar dose of captopril (12 mg/kg). In RH2 dogs sodium-depleted by furosemide pretreatment and maintained on a salt-free diet to raise plasma renin activity (PRA) levels, CL 242,817 (20 mg/kg, p.o) was more effective than an equimolar oral dose of captorpril (12 mg/kg) in lowering blood pressure. In RH2 dogs, repletion of body sodium (and reduction in PRA) by maintenance on a normal sodium diet for 14 days decreased the antihypertensive effect of CL 242,817 and abolished that of captopril. The data suggest that angiotensin converting enzyme inhibitors (ACEI) are more effective in models in which PRA is elevated and the hypertension appears to be renin-dependent. The RH₂ dog that is sodium-depleted by furosemide and mainted on a sodium-free diet appears to be a suitable model for evaluating the antihypertensive effects of ACEI.     

Effect of captopril and hydrochlorothiazide on the response to pressor agents in hypertensives

The effect on arterial pressure of incremental doses of norepinephrine (2 to 10 micrograms/min) and angiotensin II (50 to 800 ng/min) administered over 10 min periods was studied in sodium-replete hypertensive patients after crossover oral treatments with placebo, captopril 50 mg in a single dose, captopril 50 mg three times daily for one week and hydrochlorothiazide 50 mg daily for a week. Neither captopril nor hydrochlorothiazide affected the dose response to infusions of angiotensin II. In comparison to placebo responses, however, both single and multiple-dose captopril therapy, and hydrochlorothiazide attenuated the pressor responses to infusions of norepinephrine. Captopril significantly depressed angiotensin converting enzyme activity from pre-dose levels and angiotensin II infusions significantly elevated plasma aldosterone concentrations. These results confirm findings reported for single dose captopril in normotensive volunteers and indicate that attenuation of the vascular responsiveness to sympathetic stimulation may contribute to the antihypertensive effects of captopril and hydrochlorothiazide therapy.