Short term effects and urinary excretion of the new diuretic, indapamide, in normal subjects

Genetic polymorphisms of metabolic enzymes and the pharmacokinetics of indapamide in Taiwanese subjects

To understand the genetic makeup and impact on pharmacokinetics (PK) in the Taiwanese population, we analyzed the pharmacogenetic (PG) profile and demonstrated its effects on enzyme metabolism using indapamide as an example. A multiplex mass spectrometry method was used to examine the single nucleotide polymorphism (SNP) profile of eight major phases I and II metabolic enzymes in 1,038 Taiwanese subjects. A PG/PK study was conducted in 24 healthy subjects to investigate the possible effects of 28 SNPs on drug biotransformation. Among the genetic profile analyzed, eight SNPs from CYP2A6, CYP2C19, CYP2D6, CYP2E1, CYP3A5, and UGT2B7 showed higher variant frequencies than those previously reported in Caucasians or Africans. For instance, we observed 14.7% frequency of the SNP rs5031016 (I471T) from CYP2A6 in Taiwanese, whereas 0% variation was reported in Caucasians and Africans. The PG/PK study of indapamide demonstrated that the polymorphic SNPs CYP2C9 rs4918758 and CYP2C19 rs4244285 appeared to confer lowered enzyme activity, as indicated by increased C max (25% ∼ 64%), increased area under the plasma level-time curves (30~76%), increased area under the time infinity (43% ∼ 80%), and lower apparent clearance values than PK for wild-type indapamide. Our results reinforce the biochemical support of CYP2C19 in indapamide metabolism and identify a possible new participating enzyme CYP2C9. The PG/PK approach contributed toward understanding the genetic makeup of different ethnic groups and associations of enzymes in drug metabolism. It could be used to identify two genetic markers that enable to differentiate subjects with varied PK outcomes of indapamide.

Cardiovascular protective properties of indapamide

Although indapamide has been used for many years as a first-line treatment of hypertension, it is only recently that some of its activities on the changes of the cardiovascular system, brought on by age and high blood pressure, have been studied. Indapamide appears to reduce blood pressure by a combined diuretic and direct vascular activity reducing vascular reactivity and total peripheral resistance. In addition, it has discrete effects on a number of interrelated systems that may protect the cardiovascular system. Indapamide reduces intracellular calcium levels, maintains magnesium ions, but reduces phosphate ions that may be involved in arterial rigidity. Circulating catecholamines remain unchanged but there is a reduction in normetanephrine, suggesting a reduction in sympathetic tone. It stimulates prostacyclin synthesis, increases levels of circulating prostacyclin, reduces platelet aggregation and stimulates the vasodilation elicited by endothelium-derived relaxing factor in the presence of bradykinin. In addition, it inhibits the formation of the vasoconstrictor prostanoid, thromboxane A2. The free radical scavenging activity of indapamide could also protect the vascular smooth muscle from the reperfusion injury of cerebral and myocardial ischemia. Indapamide induces a reduction in cerebral ischemia after carotid ligation. Unlike some other antihypertensives, it does not upset the high-density/low-density lipoprotein-cholesterol balance, reducing the possible risk of atherosclerosis. Moreover, the combination of binding to elastin and reduction in uptake of calcium and phosphate into the smooth muscle could be a mechanism for reducing arterial rigidity seen in the elderly and hypertensive patient. In hypertensive patients, these properties induce an improvement in arterial compliance, and in the long term a reduction in left ventricular hypertrophy. These pharmacologic and clinical results, together with a good antihypertensive efficacy and acceptability, suggest that indapamide may be a preferential agent in the long-term cardiovascular protection of the hypertensive patient.

Liquid chromatographic screening of diuretics in urine

We describe a liquid chromatographic screening procedure for the detection, in urine, of twelve of the fifteen potassium-depleting diuretics available in Australia. A 2-ml urine sample was acidified with NaH2PO4 (pH 4.1) and extracted with 4 ml ethyl acetate. The sample was cleaned up further by washing with 5 ml Na2HPO4 (pH 7.5). The ethyl acetate was then evaporated to dryness, the residue reconstituted in 100 microliters mobile phase and 5 microliter were injected onto a Merck LiChrosorb RP-18 (5 microns) column. The ultraviolet absorbance of the eluent was monitored at 271 nm for 10 min. The screen was evaluated by giving each of thirty volunteers the lowest recommended dose of one of the diuretics in the study and obtaining urine samples 4, 8 and 24 h after having taken the dose. Twelve diuretics, chlorothiazide, hydrochlorothiazide, quinethazone, chlorthalidone, methyclothiazide, clopamide, frusemide, metolazone, mefruside, bendrofluazide, cyclopenthiazide and bumetanide, were all detectable up to 24 h after a dose. We therefore conclude that the screen would be reliable for the detection of these diuretics in urine.

A review of 10 years of experience with indapamide as an antihypertensive agent

Indapamide is an effective antihypertensive agent for which a dual mechanism of action has been put forward: a limited diuretic activity combined with antivasoconstrictive effects, resulting in decreased peripheral vascular resistance. Results from clinical trials show that 2.5 mg indapamide once daily effectively reduces arterial blood pressure in about two-thirds of patients with mild to moderate hypertension and that this reduction is related to the severity of the hypertension. As a rule, indapamide's blood pressure-reducing effect is rapid in onset (within 1 or 2 weeks) and by 1 month reaches 65% of its maximum, which occurs after 3 to 4 months of treatment. No tachyphylaxis has been observed during long-term treatment, nor has withdrawal syndrome at discontinuation of therapy. Indapamide has been successfully combined with beta blockers, methyldopa, and other antihypertensive agents, adding considerable effectiveness without noticeable increase in adverse reactions. In general, the drug is well tolerated and side effects are mild and rare. Possibly in relation to its limited diuretic activity at 2.5 mg daily, long-term treatment seldom elicits significant changes in electrolyte balance. In addition, indapamide does not induce deleterious effects on carbohydrate and lipid metabolism. Indapamide is an effective, well-tolerated, first-line antihypertensive agent. The fact that long-term administration does not induce biochemical abnormalities that constitute cardiovascular risk factors indicates another advantage of the drug.

Indapamide. A review of its pharmacodynamic properties and therapeutic efficacy in hypertension

Indapamide is an orally active sulphonamide diuretic agent. Although some evidence appears to indicate that the antihypertensive action of indapamide is primarily a result of its diuretic activity, only a limited diuresis occurs with the usual antihypertensive doses of 2.5 mg daily, and in vitro and in vivo data suggest that it may also reduce blood pressure by decreasing vascular reactivity and peripheral vascular resistance. In mild to moderate hypertension it is as effective as thiazide diuretics and beta-adrenergic blocking agents in lowering blood pressure when used as the sole treatment. Indapamide has been successfully combined with beta-adrenergic blocking agents, methyldopa, and other anti-hypertensive agents. While such findings need confirmation, it appears that indapamide shares the potential with other diuretic agents to induce electrolyte and other metabolic abnormalities, although it may do so with less frequency or severity. Thus, indapamide appears to offer a suitable alternative to more established drugs as a 'first-line' treatment in patients with mild to moderate hypertension. Whether it differs significantly from other diuretics when used as antihypertensive therapy, either in its mode of action or its side effect profile, needs further clarification.

Clinical efficacy, safety, and pharmacokinetics of indapamide in renal impairment

The efficacy and safety of a new diuretic-antihypertensive drug, indapamide (2.5 mg/day), were evaluated in hypertensive patients with normal renal function, in patients with various degrees of chronic renal failure, and in hypertensive patients undergoing long-term maintenance hemodialysis. The results obtained from single-blind, placebo-controlled studies indicate that indapamide is a safe and effective agent to use in lowering the blood pressure of hypertensive patients with normal renal function, those with various degrees of renal impairment, and those who are undergoing long-term maintenance hemodialysis. No significant side or toxic effects were noted in these studies. Furthermore, indapamide does not accumulate in the bloodstream of patients with renal impairment and is not dialyzable.

Clinical efficacy and safety of indapamide in the treatment of edema

Whether edema is caused by "overflow" or "underfill," the excess retention of salt and water is common to virtually all forms. The use of natriuretic agents has been shown to be effective in most cases of edema. The present study compares the efficacy of a new long-acting indoline compound, indapamide, with that of hydrochlorothiazide, both given once daily, in the treatment of edema. This double-blind study was conducted in 17 centers. Edema was evaluated by weight change and pitting of the lower extremities. Indapamide was given in doses of 2.5, 5.0, and 10.0 mg and was compared with 100 mg of hydrochlorothiazide. Active treatment was continued up to 12 weeks. Weight change efficacy evaluation was done on 219 patients, and efficacy analysis for pitting edema was done on 214 patients. Of the 219 subjects, 90 were men and 129 were women. Mean age was 57.4 years, and mean body weight was 88.5 kg. By the end of 2 weeks of active treatment, the percentages of patients with no edema were 26%, 44%, and 31% for the indapamide groups (2.5, 5.0, and 10.0 mg), respectively, and 40% for the hydrochlorothiazide group (100 mg). Early response to treatment as measured by weight loss was demonstrated by all patients in the study regardless of treatment group. Hypokalemia was the most frequently reported adverse reaction. Other adverse reactions were infrequent, with no significant difference among the treatment groups. This study concluded that indapamide in once-daily oral doses of 2.5, 5.0, or 10.0 mg was as safe and effective as a once-daily 100 mg dose of hydrochlorothiazide for the treatment of 219 patients with edema from various causes.

Some wrong-way chemical changes during antihypertensive treatment: comparison of indapamide and related agents

Despite the beneficial therapeutic effects of antihypertensive drugs, some agents--particularly diuretics--seem to go in the "wrong direction" chemically. In fact, these changes could counteract some of the benefits resulting from lowering a patient's blood pressure. In the absence of hard evidence of the efficacy of long-term diuretic treatment of mild hypertension, we must be maximally sure that such therapy causes no harm. Thiazide and related diuretics have been associated with four distinct wrong-way chemical changes: increases in plasma concentrations of cholesterol, glucose, and uric acid, and a decrease in plasma potassium levels. The potential ramifications of such changes are well understood. The increase in circulating cholesterol, an established risk factor of myocardial infarction and stroke, is of particular concern--each year approximately one million hypertensive patients have myocardial infarctions. As a result, the search for safer and more effective diuretics must continue. Indapamide, a new antihypertensive drug, appears to meet these criteria. It is an effective diuretic with a considerable peripheral vasodilatory effect. Additionally, it does not appear to induce any significant change in circulating cholesterol, whereas chlorthalidone has been found to increase total cholesterol by 5%. Hydralazine is the only antihypertensive agent that seems to lower total cholesterol levels significantly. Neither indapamide nor hydralazine appears to affect plasma glucose levels; benzothiadiazines, however, have been found to induce an increase in circulating glucose.

Clinical efficacy and safety of indapamide in essential hypertension

Indapamide, a new methylindoline diuretic that appears to act on the distal renal tubules, is also reported to reduce vascular smooth muscle vasopressor reactivity and possibly to have a calcium-antagonist effect. Since 1973, sixteen studies by a number of European investigators who treated 301 patients with indapamide have revealed satisfactory control in 53% of patients with mild hypertension (standing diastolic pressures less than 90 mm Hg) and in 43% of patients with moderate hypertension when the drug was used without other agents. Multiple American clinical trials of indapamide in hypertension have been conducted, including double-blind, placebo-controlled protocols and trials comparing indapamide with traditional diuretic agents. A cooperative, double-blind, 40-week study compared antihypertensive response to indapamide, 2.5 mg and 5 mg daily, with response to hydrochlorothiazide, 50 mg daily, in the treatment of mild to moderate hypertension. Pretreatment diastolic blood pressures averaged 101 mm Hg. At 40 weeks of treatment, indapamide, 2.5 mg daily, had produced a fall in diastolic pressure of 15 mm Hg; indapamide, 5 mg daily, a reduction of 16 mm Hg; and hydrochlorothiazide, 50 mg daily, a fall of 15 mm Hg. Seventy-five percent of patients taking 2.5 mg of indapamide daily and 88% of those taking 5 mg achieved satisfactory blood pressure reduction. Hypokalemia may occur with indapamide but is a minor problem and seldom necessitates potassium supplementation. Serum uric acid increases were observed in only a few subjects, and clinical side effects are infrequent and mild. Indapamide is a useful antihypertensive agent with good patient tolerance in mild or moderate hypertension and may offer advantages over traditional diuretics in view of its possible vasodilator and calcium-antagonist properties, once-a-day dosage, and good therapeutic effect with prolonged usage.

Indapamide and atenolol in the treatment of hypertension: double-blind comparative and combination study

Fifteen out-patients with moderate hypertension were randomly and sequentially treated with atenolol, indapamide and a combination of the two drugs after a wash-out period of at least 1 week and a 2-week placebo run-in period. The duration of treatment was 4 weeks in each case. The dosage was 2.5 mg indapamide and 100 mg atenolol, in single tablets which were taken at 11.00 hours. All the treatment regimens produced a highly significant (p less than 0.001) reduction in systolic and diastolic, supine and standing blood pressure; these reductions were not significantly different for the single drugs but were significantly greater for the combined therapy. The number of patients reaching the end-point of a diastolic blood pressure of 95 mmHg or less was the same with either atenolol or indapamide, i.e. 7 (46.6%), but was greater with the combined therapy, i.e. 10 (66.6%). A significant (p less than 0.001) reduction in pulse rate was observed with the treatments involving atenolol. Acceptability of the treatments was very good; the number of volunteered and elicited complaints during the different treatments being less compared to the placebo period, particularly for the combined treatment. No significant difference was observed in the blood biochemistry tests. The results are discussed in light of the mechanisms of action of the two drugs, which seem well integrated with each other, and the duration of the antihypertensive effect, which allows a single administration with consequent good treatment compliance.

The effects of long term oral treatment with indapamide on the development of DOCA-salt hypertension in rats: vascular reactivity studies

The onset of DOCA-salt hypertension in male Sprague-Dawley rats was prevented during 11 weeks of oral treatment with indapamide (0.5, or 10.0 mg/kg) or propranolol (60 mg/kg) administered in the diet. The body weights of the indapamide treated groups were significantly (P < 0.01) greater, at weeks 4, 5, 6, 7 and 11, while the body weights and food intake of the propranolol treated group were significantly (P < 0.05) lower at week 11, than the control group. A significant reduction in heart wet weight (P < 0.001) was measured in the indapamide treated animals only. No significant diuresis nor natriuresis was measured in any group during week 11 of treatment. When all groups were subjected to an increased salt load, four weeks after cessation of drug treatment only the indapamide (10 mg/kg) treated animals failed to show an increased blood pressure. Vascular reactivity studies carried out six weeks after termination of drug treatment, indicated a significant (P < 0.01) reduction in pressor activity elicited by electrical stimulation of the entire sympathetic outflow in indapamide (10 mg/kg) treated pithed rats. No significant difference in the pressor activity elicited by noradrenaline (5 x 10(-8) - 5 x 10(-6) g/kg, i.v.) or tyramine (10(-5) - 5 x 10(-5) g/kg i.v.) was observed in any treatment group. In conclusion, chronic oral treatment with indapamide or propranolol, prevented the onset of DOCA-salt hypertension in rats. A long lasting antihypertensive action of indapamide involving the sympathetic nervous system is also indicated.

Fluorometric assay for urinary indapamide

A sensitive fluorescence method for the determination of indapamide was developed. Reaction of indapamide with sodium hydroxide at 100 degrees yielded a fluorescent product, and addition of formaldehyde to the fluorescent product increased its fluorescence intensity by a factor of three. The assay is sensitive to levels of indapamide of 0.025 microgram/ml in an aqueous solution, and a linear response between 0.025 and 2.0 microgram/ml was observed. The procedure was adapted to the analysis of intact indapamide in urine. Concentrations of indapamide of 0.05 microgram/ml can be detected in dogs given 20 mg of the drug.

A double-blind study in hypertensive patients of an original new compound, indapamide

In a double-bind crossover study in 18 patients with essential hypertension, the hypotensive activity of 5 mg. indapamide daily was compared with 40 mg. frusemide daily over a period of 4 months after an initial 15 days on placebo. The overall clinical assessment showed satisfactory blood pressure control in 72% of patients receiving indapamide compared with 57% on frusemide. The weight of patients on active therapy dropped significantly with both products, but to a greater extent with indapamide. Indapamide was well-tolerated by all 18 patients; 3 patients on frusemide developed side-effects. The results of blood chemistry investigations are discussed. Variations in potassium levels during indapamide therapy were modest and did not warrant the use of potassium supplements.

Antihypertensive activity of a new agent, indapamide: a double-blind study

In a double-blind trail in 22 patients with mild to moderate essential hypertension, indapamide was compared with chlorathiazide and placebo. Dosage levels were set at 5 mg. indapamide and 500 mg. chlorothiazide daily, for 5 days out of 7, and patients were treated alternately, in random sequence, with each drug for a month over a 3-month period. Blood pressure readings and blood chemistry investigations were carried out before and after each treatment period and a careful history was kept of subjective symptoms and patients' tolerance of therapy. The results show that both active treatments produced drops in systolic and diastolic pressures, but were only statisically significant and different from placebo in the case of indapamide. Indapamide also produce much greater subjective improvement (74%) in patients with functional symptoms compared with chlorothiazide (15%). In an overall assessment, indapamide produced an excellent to good response to treatment in 57% of patients. Comparable responses for chlorotiazide and placebo were 25% and 20% respectivlely. Using patients as their own controls to compare the relative effectiveness of the three periods of treatment, indapamide was shown to be more effective than placebo in 65% of cases and more effective han chlorothiazide in 60%. Although patient tolerance of indapamide was slightly better, both drugs were well accepted and no significant changes from baseline levels were noted in any of the laboratory parameters investigated.