Anticancer activity of indapamide adsorbed on gold nanoparticles: DFT, in-silico, and in-vitro analysis.

The adsorption properties of the lung cancer agent indapamide (IND) on gold nanoparticles (AuNPs), were studied with the help of surface-enhanced Raman scattering techniques. The structure-activity of the IND and INDA molecule has been studied using DFT/B3LYP methodology. NBO analysis reveals that, both the molecules are stabilized by a C─H… O intramolecular hydrogen bonding, apart from the conjugative and intramolecular charge transfer interactions. The analysis of the electron density of frontier molecular orbital analysis gives a comparative idea of the reactivity, the low kinetic stability, and low value of energy gap indicating the electron transport in the molecule and thereby its bioactivity. The molecular electrostatic potential, local and global reactivity indicators predict the reactive site of the molecules. FT-IR, FT-Raman, and surface-enhanced Raman scattering have been investigated and compared with the theoretical prediction. Effective in-silico (molecular docking) biological activity screening of the molecules was checked on lung cancer cells. In-vitro (surface-enhanced Raman scattering techniques and MTT assay) analysis confirms the results from the in-silico analysis. This study promotes the potential of SERS agents for targeted drug delivery and photothermal therapy and the novelty of the IND and INDA molecule against lung cancer activity.

Simultaneous Evaluation of Dissolution and Permeation of Oral Drug Solid Formulations for Predicting Absorption Rate-Limiting Factors and In Vitro-In Vivo Correlations: Case Study Using a Poorly Soluble Weakly Basic Drug.

Combined dissolution and permeation systems are designed to simultaneously assess the dissolution of a pharmaceutical dosage form and the permeation of dissolved drugs therefrom. However, there were still some limitations on predicting the possible absorption rate-limiting steps and improving the in vitro-in vivo correlation (IVIVC) of a complete dosage form. In this study, the modified biorelevant media with some solubilizers and pH modifiers were integrated into the drug dissolution/absorption simulating system (DDASS). Indapamide, a poorly soluble compound (pKa = 8.8), was selected to validate the applicability of the modified biorelevant media. The elution and permeation dynamics of indapamide were investigated by using appropriate solubilizing agents in the DDASS. The absorption behaviors were analyzed after oral administration of indapamide in beagle dogs. The absorption rate-limiting steps and IVIVCs were predicted from the dissolution-permeation-absorption dynamic parameters. As a result, the absorption fraction of indapamide in the FaSSIFmod of DDASS was estimated to be approximately 100%, in accordance with its high permeability. The ratios of permeation rate to elution rate were 2.55 and 3.34 for the immediate- and sustained-release tablets of indapamide, respectively, suggesting a dissolution rate-limiting absorption for indapamine. In addition, point-to-point correlations were established between in vitro elution and in vivo absorption by the nonlinear and linear regression analysis ways (r > 0.85). The findings indicate that DDASS is a promising technique to develop improved IVIVCs of a complete dosage form, and the FaSSIFmod is suitable to predict the possible absorption rate-limiting steps of poorly soluble drugs in DDASS.

Effects of some antihypertensive drugs on the metabolism and pharmacokinetics of indapamide in rats.

PURPOSE: Indapamide, a non-thiazide antihypertensive diuretic agent, has been widely coadministered with other classes of antihypertensive agents to reach target systolic blood pressure. Indapamide is extensively metabolized by cytochromes P450. Interaction of indapamide and other antihypertensive drugs are unknown. We investigated the effects of other antihypertensive drugs on the metabolism and pharmacokinetics of indapamide in vitro and in vivo. METHODS: Indapamide metabolism was studies in vitro using human liver microsomes pretreated with or without different concentrations of CYP-selective inhibitors and seven major antihypertensive drugs, felodipine, nifedipine, nitrendipine, telmisartan, irbesartan, valsartan and puerarin. Furthermore, the pharmacokinetics of indapamide was determined by HPLC-MS/MS to evaluate the effects of felodipine coadministered on the bioavailability of indapamide in rats in vivo. RESULTS: The Km and Vmax of indapamide metabolism were 114.35 ± 3.47 µM and 23.13 ± 6.61 µmol/g/min. The metabolites of indapamide, hydroxyl-indapamide and dehydrogen-indapamide, were followed. CYP3A4 and CYP2C19 were involved in indapamide metabolism in human live microsomes. In addition, felodipine, nifedipine and nitrendipine significantly inhibited indapamide metabolism with the maximum inhibitory rates of 82.6%, 72% and 95%, respectively. Felodipine significantly elevated indapamide plasma concentration and prolonged its half-life. CONCLUSIONS: Combination therapy of indapamide and felodipine might lead to the alteration of indapamide metabolism and pharmacokinetics. The consequence of such an interaction that may include increased effectiveness and side effect needs to be tudeis in human.

Effect of slow-release indapamide and perindopril compared with amlodipine on 24-hour blood pressure and left ventricular mass in hypertensive patients of African ancestry.

BACKGROUND: In the treatment of hypertension in subjects of African origins, although hydrochlorothiazide (HCTZ) is not as effective as calcium channel blockers, indapamide is superior to HCTZ. In the present study we therefore compared the effects of slow release (SR) indapamide with the calcium channel blocker amlodipine, when used as initial therapy, on blood pressure (BP) and left ventricular mass (LVM) during 6 months of treatment in this group. METHODS: Patients with a mean daytime ambulatory diastolic BP > or =90 mm Hg and < or =110 mm Hg (n = 125, aged 53 +/- 11 years, 68% women) were randomized to receive open-label 1.5 mg of indapamide SR or 5 mg of amlodipine. If daytime ambulatory diastolic BP at 1 month was >/=90 mm Hg, 4 mg of perindopril was added to indapamide SR or the dose of amlodipine was increased to 10 mg. RESULTS: After 1 month of therapy, there was an equivalent decline in systolic and diastolic BP in both groups (P <.0001). In the indapamide-treated group (n = 62) the daytime BP decreased from 153 +/- 12/101 +/- 6 mm Hg to 138 +/- 15/92 +/- 10 mm Hg and for amlodipine (n = 58), it decreased from 152 +/- 13/99 +/- 5 mm Hg to 138 +/- 12/91 +/- 8 mm Hg. At 6 months daytime ambulatory BP decreased to 130 +/- 15/86 +/- 8 mm Hg and to 129 +/- 11/85 +/- 5 mm Hg for the indapamide SR (n = 42) and amlodipine (n = 44) treatment groups, respectively. Both groups showed equivalent regression of LVM index and relative wall thickness. CONCLUSIONS: These data suggest that in hypertensive patients of African ancestry initiating therapy with 1.5 mg of indapamide SR and then adding 4 mg of perindopril is equally as effective as amlodipine therapy at reducing BP, and modifying target organ damage.

Antioxidant properties of indapamide, 5-OH indapamide and hydrochlorothiazide evaluated by oxygen-radical absorbing capacity and electron paramagnetic resonance.

The aim of these experiments was to investigate the radical scavenging properties of three diuretics: indapamide (IND) and its major metabolite, 5-OH indapamide (5-OH IND), compared to a reference diuretic, hydrochlorothiazide (HTZ). Electron Paramagnetic Resonance (EPR) was used to determine the scavenging abilities of these compounds on enzymatically produced superoxide radical anion, with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) used as a spin-trap. These experiments revealed that IND and specially 5-OH IND were effective superoxide radical anion scavengers at 0.2 mg/ml. In the second part of these studies, allophycocyanin was used as an indicator of free radical mediated protein damage. In the assay, 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) was used as a peroxyl radical generator, Trolox (a water-soluble analogue of vitamin E) as a control standard, and the loss of allophycocyanin fluorescence was monitored. The antioxidant effects of the diuretics were expressed in oxygen-radical absorbing capacity (ORAC), where one ORAC unit equals the net protection produced by 1 microM Trolox. HTZ showed no protection up to 100 microM final concentration, whereas IND and 5-OH IND showed linear correlation with respect to concentration when expressed in ORAC units: 5-OH IND induced the highest protection against peroxyl radical. The above observations suggested that IND and 5-OH IND are potent radical scavengers, with the metabolite 5-OH IND having a superior antioxidant potency than IND. By contrast, HTZ had no effect. These radical scavenging properties of 5-OH IND may be of clinical interest for vascular protection and may help to protect the heart from oxidative injury.

Identification and pharmacological properties of binding sites for the atypical thiazide diuretic, indapamide.

[3H]Indapamide bound to a single class of binding sites in pig renal cortex membranes with a dissociation constant Kd = 35 +/- 13 nM and a binding site density Bmax = 40 +/- 9 pmol/mg of protein. [3H]Indapamide binding was inhibited by the carbonic anhydrase inhibitor, acetazolamide, and by thiazide diuretics with the following rank order of potency: chlorothiazide greater than hydrochlorothiazide approximately metolazone greater than hydroflumethiazide. The effect of the latter drugs to inhibit [3H]indapamide binding was not related to their activity as thiazide diuretics, but was significantly correlated with their inhibitory effect on carbonic anhydrase II. These results suggest that the major renal binding site of [3H]indapamide is a membrane form of carbonic anhydrase. Inhibition of carbonic anhydrase may play a role in the antihypertensive effect of indapamide.

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.

Indapamide: a unique diuretic?

Indapamide (Lozol) is a new diuretic and antihypertensive agent. The drug appears to have a unique mechanism of action, combining diuretic effects with a direct vascular action, presumably secondary to calcium channel blockade. Available studies indicate that indapamide is comparable to hydrochlorothiazide, chlorothiazide, furosemide, and other diuretic agents in the management of hypertension and edema. The drug produces toxicity similar to that of the thiazide and loop diuretics; however, it does not appear to increase cholesterol levels. Although it is claimed that indapamide produces no effect on glucose levels, hyperglycemia has been reported. Indapamide is safe and effective for treatment of hypertension in mild to severe renal impairment, but advantages over furosemide are questionable. Indapamide is a unique diuretic, but does not appear to offer advantages over other available agents.

Lack of effect of bilateral nephrectomy on the pharmacokinetics of 14C-indapamide (REV 2555) and its metabolites in the dog.

Renal impairment can affect the disposition of metabolites, as well as unchanged drug, especially when there is significant renal clearance of metabolites. The pharmacokinetics of indapamide, a highly metabolized drug, and total indapamide equivalents (as an indicator of metabolites plus unchanged drug) were determined in the anephric dog. An intravenous dose of 14C-indapamide was administered to dogs first after a sham-operation, and then following bilateral nephrectomy. The disposition of total indapamide equivalents, calculated from total radioactivity, was not substantially different after nephrectomy as compared to after sham-operation, with an increase after nephrectomy in the area under the blood level curve (+26.2%), and decreases in the elimination rate constant (-6.9%), volume of distribution (-12.7%) and total blood clearance (-21.9%). The only statistically significant change was the decrease in the volume of distribution. The elimination kinetics of unchanged drug were also qualitatively similar in both cases. After nephrectomy, a decrease was seen in the elimination rate constant (-10.9%) and the volume of distribution (-16.3%) while slight increases in the total blood clearance (+1.9%) and the area under the blood level curve (+4.8%) were noted. These findings could have important implications for advantageous use of indapamide in treatment of hypertensive patients with renal failure since these data suggest that metabolites as well as unchanged drug could still be effectively eliminated by an alternate, non-renal route, thus minimizing accumulation of these compounds.

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.

Preclinical studies of indapamide, a new 2-methylindoline antihypertensive diuretic.

Indapamide is a new indoline antihypertensive diuretic agent whose chemical structure differs substantially from those of the thiazides. The hydrophobic indoline moiety of indapamide confers a lipid solubility to the molecule that is 5 to 80 times greater than that of the thiazide diuretics. Thus indapamide accumulates in vascular smooth muscle at a concentration 10 times higher than that of protein-free perfusate. The affinity of indapamide for vascular smooth muscle manifests itself in vitro and in vivo as a decrease in reactivity following various pharmacologic interventions. Moreover, in vitro studies have demonstrated that indapamide decreases the inward calcium current and the transmembrane influx of calcium. The diuretic effect of indapamide is predominantly due to inhibition of sodium reabsorption at the cortical diluting segment of the distal convoluted tubule. In animal studies, intravenous indapamide has no effect on glomerular filtration rate or renal blood flow. Indapamide is well absorbed and extensively metabolized in animals and humans, with biliary excretion being the predominant route of elimination in animals. Most important, repeat administration of indapamide to dogs with both kidneys removed produces no accumulation of intact indapamide or its metabolites. Extensive drug safety studies in animals indicate that indapamide produces no overt toxicity and exhibits a good margin of safety.

Pharmacokinetics and clinical pharmacology of indapamide.

Indapamide is a new antihypertensive diuretic agent indicated for the treatment of hypertension and edema. Indapamide shows an alteration in vascular reactivity to calcium and other agonists, suggesting the possibility of a direct vascular effect. The drug is recommended in doses of 2.5 to 5 mg once a day. It is rapidly and completely absorbed from the gastrointestinal tract, resulting in maximal blood levels in approximately 2.3 hours. Coadministration of indapamide with food or antacids does not reduce bioavailability. Linear proportionality of blood concentration with increasing doses is evident following both single and multiple doses. Other pharmacokinetic parameters are not dose related. Indapamide is widely distributed in the body with extensive binding to erythrocytes. Binding to plasma proteins is approximately 76%. Disappearance of indapamide from the blood is biphasic, with a terminal half-life of approximately 16 hours. Renal clearance represents less than 10% of the total systemic clearance of the parent drug, showing the dominant role of hepatic clearance. Studies of 14C-labeled indapamide in humans demonstrate that 70% of the radioactivity is excreted in urine and 23% in feces. Indapamide is extensively metabolized; less than 7% of the dose is excreted in urine as unchanged compound. Studies of patients with renal impairment showed little or no accumulation of indapamide in the blood in comparison to patients with normal renal function. Clinical studies demonstrate that indapamide has diuretic properties. Free water clearance studies indicate a site of action in the cortical diluting segment of the distal tubules. No adverse effect of indapamide on renal function is evident in normal volunteers, hypertensive patients, or geriatric hypertensive patients, as determined by glomerular filtration rate or effective renal plasma flow. Hemodynamic studies of indapamide in patients with mild to moderate hypertension show a significant (p less than 0.05) decrease in mean blood pressure (16%) and total peripheral resistance (15%). No other significant hemodynamic effects are evident. The data suggest that indapamide may produce antihypertensive activity through a dual mechanism of action--diuretic and direct vascular. Additionally, it appears to be safe even for patients with impaired renal function.

Effects of competitive red blood cell binding and reduced hematocrit on the blood and plasma levels of [14C]Indapamide in the rat.

The effects of chlorthalidone and acetazolamide on the red blood cell binding of indapamide were investigated. Both drugs caused a substantial decrease in the amount of indapamide bound to the erythrocytes in vitro. This effect was demonstrated by a change in the indapamide blood/plasma ratio from approximately 6 in control samples, to a value of 1 when either of the displacing agents was added. Coadministration of acetazolamide with 14C-labeled indapamide to rats, resulted in a 5-fold drop in the blood levels of total radioactivity, relative to rats dosed with [14C]indapamide alone. Concomitantly, there was a 2-fold increase in the plasma levels of total radioactivity after acetazolamide coadministration. In rats whose hematocrits had been reduced by extensive bleeding, there were only minor alterations in the blood/plasma partitioning of [14C]indapamide. Thus, chlorthalidone and acetazolamide were able to displace indapamide from erythrocytes in vitro and in vivo, possibly by competition at a carbonic anhydrase binding site. The pharmacokinetics of drugs which are extensively bound to erythrocytes may be significantly altered by the presence of other agents capable of competitive binding.

Multi-centre clinical investigation of indapamide in the United States: a review.

Indapamide, a new indoline antihypertensive agent, has been the subject of a worldwide programme to develop this drug for general clinical use. The results are described of the multi-centre U.S. clinical programme demonstrating the effectiveness and tolerance of indapamide for the treatment of hypertension. All work was conducted under U.S. Federal Food and Drug Administration guidelines, and resulted recently in a New Drug Application. A total of 1891 subjects or patients participated in 27 separate studies conducted by 91 investigators. In controlled clinical trials comparing 2.5 mg indapamide once daily with 50 mg hydrochlorothiazide once daily for 40 weeks in patients with mild to moderate essential hypertension, indapamide produced a reduction of supine blood pressure of -9.5/-14.3 mmHg as compared with -7.6/-11.4 mmHg for hydrochlorothiazide. In combination with methyldopa, propranolol, clonidine, guanethidine and hydralazine, indapamide consistently produced a greater decrease in arterial pressure than did those agents given alone. Indapamide added to these step-care agents did not result in a meaningful increase in adverse reactions. Indapamide has been the subject of a long-term safety study in which over 100 hypertensive patients have been followed up for 2 years or longer. During this period of time, indapamide was well tolerated and remained effective. No biochemical, electrocardiographic or ophthalmological changes were associated with its use. Other studies with indapamide are discussed describing the systemic and renal haemodynamic effects, pharmacokinetic properties and special safety studies conducted with this agent. The use of indapamide in patients with hepatic or renal impairment is reviewed in detail.

Pharmacokinetics and bioavailability of indapamide--a new antihypertensive drug.

Two formulations of indapamide tablets (2.5 mg) were given as a 5.0 mg dose and the subsequent blood levels were compared to those obtained after administration of a 5.0 mg solution. The study was conducted as a randomized three-way crossover design using healthy male volunteers. The drug was well tolerated by all the subjects involved. The area under the blood concentration versus time curve, extrapolated to infinity was essentially the same for all three formulations (4.2, 4.7, and 4.4 microgram-h/ml). Statistical comparison of the blood levels from the two tablets showed that one tablet had a significantly shorter time of maximum blood concentration (2.3 vs 3.5). Cmax(333ng/ml) and tmax (0.7h) values for the solution were significantly higher than either tablet. The average half-life (beta-phase) for all three formulations was 15 h, while the average systemic clearance was 20 ml/min. Indapamide has a low clearance rate and there was no evidence that the drug undergoes a first-pass effect.

Pharmacokinetics of indapamide in dogs.

Four beagle dogs received both an oral and intravenous dose (1 mg/kg) of indapamide in a crossover design. The blood levels and urinary excretion of intact indapamide were measured, and the pharmacokinetic parameters of the drug were defined. The results indicate that indapamide is completely bioavailable after an oral dose and does not undergo first-pass metabolism. Excretion of unchanged drug from the kidney accounted for only a small percentage of the drug's clearance. While the dog is very similar to the human in its handling of indapamide, the dogs clears indapamide approximately twice as fast as humans.

The pharmacology and clinical pharmacology of indapamide.

At low doses indapamide is a potent and long acting antihypertensive agent in various hypertensive animals and in man, but is without activity in normotensive subjects. A daily dose of 2.5 mg produces a minimal diuresis but at higher doses this increases without any significant augmentation of hypotensive activity. It appears to have no effect on most blood biochemical parameters, including glucose, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, noradrenaline, adrenaline, but potassium levels may decrease and uric acid and renin increase. Indapamide had no effect on renal function nor does it alter left ventricular function, electrocardiograph (ECG) or heart rate, although cardiac output may marginally increase. Total peripheral resistance is significantly decreased and it may exert its antihypertensive effect by reducing vascular reactivity to various pressor stimuli by inhibiting the net inward flow of calcium and resultant phasic contractions in vascular smooth muscle. Indapamide differs from the diuretics in that it has a comparatively high lipid solubility; it is also bound to blood proteins and elastin in vascular smooth muscle and little is eliminated in the urine. It may be for these reasons that the drug has less diuretic activity but more pronounced effect on vascular smooth muscle than compounds of similar structure.