Smart Spectrophotometric Methods for Concurrent Determination of Furosemide and Spironolactone Mixture in Their Pharmaceutical Dosage Forms

Abstract Simple, precise, accurate and specific spectrophotometric methods are progressed and validated for concurrent analysis of Furosemide (FUR) and Spironolactone (SPR) in their combined dosage form depend on spectral analysis procedures. Furosemide (FUR) in the binary mixture could be analyzed at its λmax 274 nm using its recovered zero order absorption spectrum using constant multiplication method (CM). Spironolactone (SPR) in the mixture could be analyzed at its λmax 238 nm by ratio subtraction method (RS). Concurrent determination for FUR and SPR in their mixture could be applied by amplitude modulation method (AM), absorbance subtraction method (AS) and ratio difference (RD). Linearity ranges of FUR and SPR were (2.0µg/mL-22.0 µg/mL) and (3.0µg/mL-30.0 µg/mL), respectively. Specificity of the proposed spectrophotometric methods was examined by analyzing the prepared mixtures in laboratory and was applied successfully for pharmaceutical dosage form analysis which have the cited drugs without additives contribution. The proposed spectrophotometric methods were also validated as per as the guidelines of ICH. Statistical comparison was performed between the obtained results with those from the official methods of the cited drugs, using one-way ANOVA, F-test and student t-test. The results are exhibiting insignificant difference concerning precision and accuracy

Sevelamer reduces the efficacy of many other drugs.

(1) Sevelamer, a phosphate-binding polymer, is used to treat hyperphosphataemia in patients with chronic renal failure. Pharmacokinetic studies and some clinical reports have shown that sevelamer binds many drugs, including furosemide, ciclosporin and tacrolimus, thus making them less effective; (2) It is best to take sevelamer some time before or after other drugs.

Efecto de un incremento en la diuresis sobre la absorción y retención de algunos nutrientes en ratas / Effect of an increase in diuresis on absorption and retention of some nutrients in rats

Estudios previos en ratas han demostrado que la administración del diurético furosemida aumenta la pérdida urinaria de electrolitos y nutrientes, causando un efecto negativo sobre las reservas de los mismos. Una alternativa para proteger esas reservas es incrementar la absorción intestinal. Así, se evaluó la absorción, pérdidas urinarias y reservas corporales de nitrógeno, calcio, magnesio, sodio, potasio y cinc, en cuatro grupos de ratas: control, y tres grupos experimentales que consumieron furosemida en concentraciones de 0,5; 1,0 y 1,5 mg/g de dieta, durante 23 días. El diurético causó poliuria dosis dependiente, disminución en el consumo de alimento, la eficiencia y el crecimiento. También, provocó un aumento en las pérdidas urinarias del nitrógeno y minerales. La absorción de nitrógeno, calcio y cinc no se modificó, mientras que la del magnesio, sodio y potasio aumentó ligeramente. Se determinó que la absorción no compensó las pérdidas urinarias. Así, la furosemida afectó negativamente la retención de nutrientes y electrolitos, provocando una reducción en las reservas corporales de los mismos. Este diurético tiene un efecto negativo sobre el estado nutricional en ratas, causado por la reducción en el consumo de alimento, así como en la utilización de los nutrientes consumidos. La reducción en la utilización de los nutrientes asociada con este diurético, puede ser explicada en parte, por una pobre retención de nutrientes por el riñón, que no puede ser compensada por un incremento en la absorción intestinal.

Previous studies have shown that, in rats, the administration of the diuretic furosemide increases diuresis as well as urinary loss of electrolytes and essential nutrients. This loss has a negative effect on electrolytes and nutrient reserves. Since one alternative to help protect these reserves is to increase intestinal absorption, the purpose of this study was to evaluate the absorption, urinary loss and tissue reserves of nitrogen, calcium, magnesium, sodium, potassium and zinc in rats offered 0, 0.5, 1.0 and 1.5 mg furosemide per g diet, daily during 23 days. The diuretic caused a dose dependent polyuria, a reduction in food intake, growth and feed efficiency. In addition, those rats had increased urinary loss of nitrogen and minerals. Nitrogen, calcium and zinc absorption were not affected, but magnesium, sodium and potassium increased slightly. Intestinal absorption could not compensate for urinary loss. In general, this study showed that in rats, this diuretic had a negative effect on nutritional status caused by a reduction in food intake and also in the utilization of the nutrients consumed. The reduction in nutrient utilization associated with this diuretic may be partly explained by a poor nutrient retention by the kidney which was not compensated by an increase in intestinal absorption.

Contributions of saturable active secretion, passive transcellular, and paracellular diffusion to the overall transport of furosemide across adenocarcinoma (Caco-2) cells.

Furosemide permeation across Caco-2 cells was investigated to determine if previously reported directional differences in transport rates are due to a saturable, energy dependent process. In addition, studies were carried out to determine the route of permeation for this drug. By comparing apical (A) to basolateral (B) and B to A directional transport across Caco-2 cells, a saturable, nonlinear component to furosemide transport was observed. Transport in the secretory direction was fit to yield the following apparent parameters K(m) = 63 +/- 28 microM, V(max) = 436 +/- 137 pmol/cm(2)h, and P(app) = 3.7 +/- 0.9 x 10(-7) cm/s. Evidence of energy dependence was demonstrated using both metabolic inhibition, and transport against a diffusion gradient methods. Disruption of tight junctions by use of the calcium chelator, EGTA, caused a significant increase in furosemide transport (twofold and 12-fold increases in B to A and A to B, respectively) indicating the importance of the paracellular route. We conclude that furosemide secretion from Caco-2 cells is the result of saturable active transport and passive diffusion that has a significant paracellular component.

Aspirin inhibits the acute venodilator response to furosemide in patients with chronic heart failure.

OBJECTIVES: We sought to determine the effect of aspirin on the venodilator effect of furosemide in patients with chronic heart failure (CHF) BACKGROUND: Furosemide has an acute venodilator effect preceding its diuretic action, which is blocked by nonsteroidal anti-inflammatory, drugs. The ability of therapeutic doses of aspirin to block this effect of furosemide in patients with CHF has not been studied. For comparison, the venodilator response to nitroglycerin (NTG) was also studied. METHODS: Eleven patients with CHF were randomized to receive placebo, aspirin at 75 mg/day or aspirin at 300 mg/day for 14 days in a double-blind, crossover study. The effect of these pretreatments on the change in forearm venous capacitance (FVC) after 20 mg of intravenous furosemide was measured over 20 min by using venous occlusion plethysmography. In a second study, the effect of 400 microg of sublingual NTG on FVC was documented in 11 similar patients (nine participated in the first study). RESULTS: Mean arterial pressure, heart rate and forearm blood flow did not change in response to furosemide. After placebo pretreatment, furosemide caused an increase in FVC of 2.2% (95% confidence interval [CI] -0.9% to 5.2%; mean response over 20 min). By comparison, FVC fell by -1.1% (95% CI -4.2% to 1.9%) after pretreatment with aspirin at 75 mg/day, and by -3.7% (95% CI -6.8% to -0.7%) after aspirin at 300 mg/day (p = 0.020). In the second study, NTG increased FVC by 2.1% (95% CI -1.6% to 5.8%) (p = 0.95 vs. furosemide). CONCLUSIONS: In patients with CHF, venodilation occurs within minutes of the administration of intravenous dose of furosemide. Our observation that aspirin inhibits this effect further questions the use of aspirin in patients with CHF.

Attenuation by phenylbutazone of the renal effects and excretion of frusemide in horses.

The objectives of this study were to determine the effect of phenylbutazone premedication on the pharmacokinetics and urinary excretion of frusemide in horses; and on frusemide-induced changes in urinary electrolyte excretion. Six Standardbred mares were used in a 3-way crossover design. The pharmacokinetics and renal effects of frusemide (1 mg/kg bwt i.v.) were studied with and without phenylbutazone premedication (8.8 mg/kg bwt per os 24 h before, followed by 4.4 mg/kg bwt i.v. 30 min before frusemide administration). A control (saline) treatment was also studied. Administration of frusemide without phenylbutazone led to diuresis, natriuresis, kaliuresis and chloruresis, and altered the ratio of sodium:chloride excretion from 0.4 to 1.0 in the first hour of diuresis. When frusemide and phenylbutazone were administered, sodium and chloride excretion in the first hour were significantly (P<0.05) reduced by 40 and 32%, respectively, when compared to frusemide administrationwithout phenylbutazone. The fractional clearance of sodium and chloride was also significantly reduced. Potassium excretion, potassium fractional clearance and the ratio of sodium to chloride excretion were not affected by administration of phenylbutazone. During peak diuresis, phenylbutazone did not affect the efficiency of frusemide with respect to electrolyte excretion. The plasma disposition of frusemide was not affected by phenylbutazone. However, the renal excretion of frusemide decreased by approximately 25%. We conclude that the decreased urinary excretion of frusemide by phenylbutazone led to an attenuation of frusemide-induced increases in urinary excretion of sodium and chloride. Since the efficiency of frusemide was not affected by phenylbutazone, we conclude that phenylbutazone attenuates the renal excretion of frusemide without inhibiting the intrarenal activity of frusemide in horses.

Effect of selective inhibition of the inducible cyclooxygenase on renin release in healthy volunteers.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) can block renin release via inhibition of cyclooxygenase (COX). The responsible COX-isoenzyme in man is unknown. Therefore, we assessed the effects of meloxicam, a selective inhibitor of COX-2, and indomethacin, an unselective inhibitor of COX-1 and COX-2, on furosemide stimulated plasma renin activity (PRA). METHODS: In a randomized cross-over design 15 healthy female volunteers received no NSAID or meloxicam 7.5 mg/d for 6 days or indomethacin 25 mg tid for 2 days and 25 mg on the 3rd day. On the control day and on the last day of each treatment the following parameters were evaluated before and after furosemide 20 mg i.v.: PRA measured by RIA, urinary excretion of prostaglandin E2 (PGE2) assessed by gas chromatography-tandem mass spectrometry, urine volume and urinary excretion of sodium, potassium, and creatinine, and serum concentrations of sodium, potassium, and creatinine. RESULTS: Furosemide led to a more than two-fold rise of PRA. Indomethacin as well as meloxicam had no significant effect on basal PRA but inhibited the furosemide-stimulated PRA increase. PGE2 excretion on the control day rose two-fold after furosemide. Meloxicam had no effect on basal PGE2 excretion, whereas indomethacin reduced this parameter by 30%. Both drugs inhibited the increase of urinary PGE2 after furosemide. No drug effects on urine flow nor on electrolytes and creatinine in serum and urine could be observed. CONCLUSION: Meloxicam inhibited furosemide stimulated renin release, suggesting that in man COX-2 is responsible for prostaglandin synthesis mediating renin release.

Role of the kidneys in the metabolism of furosemide: its inhibition by probenecid.

The site where furosemide is metabolized and the location where probenecid reduces furosemide metabolism remain poorly defined. The liver appears to play a minor role, and there is indirect evidence suggesting that the kidneys could be responsible for the metabolism of furosemide. To assess the role of the kidneys in the metabolism of furosemide, its intravenous kinetics have been studied in control and anephric rabbits, after the ligation of the renal pedicles. Two additional groups of rabbits, control and anephric, have received probenecid before the administration of furosemide. In the control group, the total clearance of furosemide was 18.65 +/- 1.01 mL/ min per kg; urinary and metabolic clearances of furosemide were 7.95 +/- 0.65 and 10.70 +/- 1.11 mL/min per kg, respectively. In anephric rabbits, total clearance was reduced by 85% to 2.69 +/- 0.26 mL/min per kg (P < 0.001), secondary to the abolition of furosemide renal excretion and to the reduction in metabolic clearance from 10.70 +/- 1.11 to 2.69 +/- 0.26 mL/min per kg (P < 0.001). The pretreatment with probenecid reduced the total clearance of furosemide by 80%, to 3.62 +/- 0.24 mL/min per kg (P < 0.001), because of a reduction of 90 and 75% in urinary and metabolic clearances, respectively. The administration of probenecid to anephric rabbits did not reduce further the metabolic clearance. It is concluded that the kidneys are responsible for 85% of furosemide total clearance, either via excretion (43%) or biotransformation (42%), and that probenecid inhibits both processes.

Effects of sodium bicarbonate and ammonium chloride on the incidence of furosemide-induced fetal skeletal anomaly, wavy rib, in rats.

Furosemide produces fetal wavy ribs when administered to pregnant rats during late gestation. The compound is also known to produce metabolic alkalosis in laboratory animals and man. In order to evaluate the effect of furosemide on maternal blood pH, Crj:CD(SD) female rats received an oral administration of 150 or 200 mg/kg of furosemide by gavage on day 16 of gestation and were bled at 4 hr post-dose. Compared to an average pH of 7.39 in control females, there was a significant elevation in blood pH in these furosemide-treated females (average pH of 7.44 to 7.48). When 2% sodium bicarbonate was provided in the drinking water for females treated with 150 mg/kg of furosemide, there was a further rise in maternal blood pH (7.52) compared to females treated with furosemide alone. Associated with this elevation in maternal blood pH was a marked increase in the incidence of fetal wavy ribs (87.6% compared to 27.6%). When females treated with 200 mg/kg of furosemide were provided with 0.5% ammonium chloride, furosemide-induced maternal alkalosis was corrected (pH decreased to 7.35) and there was a reduction in the incidence of fetal wavy ribs (7.0% compared to 37.2%). In addition, maternal blood pH among individual females was positively correlated with the incidence of fetal wavy ribs (r = 0.714). These results suggest that maternal metabolic alkalosis is involved in the pathogenesis of furosemide-induced wavy ribs.

Influence of lisinopril on urinary electrolytes excretion after furosemide in healthy subjects.

It has been reported that the urinary excretions of chloride (Cl), potassium (K), and magnesium (Mg), but not sodium (Na), after furosemide, a loop diuretic, were decreased by pretreatment with lisinopril, an ACE inhibitor in hypertensive subjects. The electrolytes disturbance induced by furosemide might be ameliorated by lisinopril. The present study re-examines this potential drug interaction in healthy subjects. Lisinopril (20 mg) or its matching placebo was given orally using a double-blind, crossover design. Four hours after lisinopril administration, furosemide (20 mg) was injected intravenously and urine was collected during the following intervals: 0-0.5, 0.5-1, 1-1.5, 1.5-2, 2-3, 3-4, and 4-6 hours. Blood samples for plasma furosemide concentration were obtained at 0.5, 1, 1.5, 2, 3, 4, and 6 hours after the agent. There were no significant differences between the two trials in plasma concentrations of furosemide or urinary excretions of the agent. Urine volume and urinary excretions of electrolytes (Na, Cl, K, and Mg) after the furosemide with lisinopril administration were not significantly different from those of placebo at any observation period. These results suggest that the urinary excretions of electrolytes after furosemide administration are not influenced by pretreatment with lisinopril.

Flunixin meglumine blocks frusemide-induced bronchodilation in horses with chronic obstructive pulmonary disease.

Six horses that developed acute airway obstruction (heaves) when housed in a barn and fed poor-quality hay were studied. Airway obstruction was verified by a maximal change in pleural pressure during tidal breathing (delta Pplmax) of at least 15 cmH2O. Frusemide (1.0 mg/kg bwt) or an equivalent volume of vehicle was then administered intravenously (iv) and lung function was measured 15, 30, 60, 120, 180, 240 and 300 mins after drug administration. The effect of frusemide on lung function was also studied after treatment of horses with the cyclooxygenase inhibitor flunixin meglumine (1.1 mg/kg every 8 h for 2 days before the experiment). Frusemide significantly reduced the delta Pplmax beginning 15 mins after drug administration. This effect persisted for 5 h. The reduction in delta Pplmax was due partly to an increase in dynamic compliance and partly to a decrease in pulmonary resistance. Tidal volume and respiratory frequency were unaffected by frusemide. Vehicle had no effect on lung function. Flunixin meglumine abolished the effect of frusemide on airway calibre but did not prevent diuresis. These results indicate that the effect of frusemide on airways of horses with heaves persists for at least 5 h, is mediated through prostanoids, and is not a result of diuresis.

Kinin antagonist blunts the diuretic effect of furosemide in deoxycorticosterone-treated rats.

Furosemide at a dose of 3 mg/kg body wt increased urinary volume (vehicle: 12.8 +/- 0.6; furosemide: 42.4 +/- 2.6 ml/8h, p < 0.01) and urinary sodium excretion (vehicle: 0.9 +/- 0.1; furosemide: 5.0 +/- 0.4 mM/8h, p < 0.01) in deoxycorticosterone-treated rats. These effects were associated to a decrease in mean blood pressure (from 122 +/- 4 to 113 +/- 3 mmHg, p < 0.01) and renal vascular resistances (from 15.6 +/- 0.6 to 14.3 +/- 0.7 RU, p < 0.05). The B2-receptor antagonist D-Arg[Hyp3,Thi5,D-Tic7,Oic8]-bradykinin significantly blunted the diuretic and natriuretic effect of furosemide and completely prevented the decrease in blood pressure and renal vascular resistances. The renal kallikrein-kinin system may modulate the diuretic and hemodynamic effects of furosemide in conditions of increased mineralcorticoid activity.

Chronopharmacological study of furosemide; (IX). Influence of continuous norepinephrine infusion.

Our previous studies have suggested that the adrenergic nervous system is involved in the mechanisms responsible for the time-dependent changes in the effects of furosemide in rats. To examine this hypothesis further, norepinephrine (150 micrograms/kg/hr) or its vehicle alone was infused subcutaneously by osmotic minipumps. Furosemide (30 mg/kg) was given orally at 12 am or 12 pm. Urine was collected for 8 hours after the agent, and urinary excretions of sodium and furosemide were determined. Urine volume and urinary excretion of sodium and furosemide were significantly greater at 12 am than at 12 pm in the vehicle-infused group of rats. However these administration-time-dependent changes in the effects of furosemide and its urinary amount disappeared in the norepinephrine-infused group of animals. Since chronic norepinephrine infusion is considered to disturb the axis of adrenergic nervous system, these data support the hypothesis concerning the mechanisms of this chronopharmacological phenomenon of furosemide.

Acute administration of captopril lowers the natriuretic and diuretic response to a loop diuretic in patients with chronic cardiac failure.

Angiotensin-converting enzyme inhibitors suppress plasma concentrations of the sodium retaining hormones angiotensin II and aldosterone. This action should potentiate the natriuretic and diuretic effects of loop diuretics. Some studies indicate, however, that the introduction of angiotensin-converting enzyme inhibitors for the treatment of cardiac failure is associated with transient weight gain and the development of oedema. We have compared the natriuretic and diuretic response to intravenous frusemide 40 mg alone with the natriuretic and diuretic response to intravenous frusemide 40 mg following the administration of a single dose of captopril in 12 supine male patients with stable chronic cardiac failure. Captopril lowered the 4 h diuretic response to frusemide from 1160 (60) to 685 (77) ml (P less than 0.05) and the natriuretic response from 120 (9.6) to 68 (11.7) mmol (P less than 0.05). Creatinine clearance fell after captopril from 91 (7.2) to 57 (7.7) ml min-1 (P less than 0.05). Systolic and diastolic blood pressures were lower after the administration of captopril but these changes were not significant. Plasma renin activity rose from 3.8 (1.04) to 12.34 (2.94) ng ml h-1 (P less than 0.05) and plasma angiotensin II was reduced from 24.9 (5.05) to 8.14 (1.8) pg ml-1 (P less than 0.05). Plasma aldosterone concentrations were not significantly lower following captopril. Angiotensin-converting enzyme inhibitors cause an acute fall in creatinine clearance which may reduce the effects of loop diuretics and attention must be paid to diuretic dosage when initiating angiotensin-converting enzyme inhibitors for the treatment of cardiac failure.

Interaction of ketoprofen and frusemide in man.

The effects of ketoprofen on frusemide-induced diuresis, natriuresis and renin release were studied in 12 healthy male volunteers. Each received frusemide 40 mg once daily with either ketoprofen 100 mg twice daily or placebo for two periods of 5 days separated by a treatment-free period according to a randomized, double-blind, cross-over study design. Ketoprofen significantly reduced frusemide-induced diuresis on Day 1 but not on Day 5 of treatment. The natriuresis induced by frusemide on Day 1 or Day 5 of treatment did not differ significantly whether ketoprofen or placebo was administered, although the mean urinary sodium excretion values were consistently lower following ketoprofen. Ketoprofen did not affect the kaliuretic response to frusemide on Day 1 or Day 5 of treatment. The increase in plasma renin activity after frusemide was inhibited by ketoprofen on both Day 1 and Day 5. These results suggest that ketoprofen reduces the diuresis and renin release induced by frusemide, but that the reduction in diuretic response may become less important after their repeated coadministration.

Effect of activated charcoal on frusemide induced diuresis: a human class experiment for medical students.

We have introduced to the course in pharmacology for medical students a simple human experiment that demonstrates the efficacy of activated charcoal in gastrointestinal drug binding. Sixty-one students were given 40 mg frusemide with water, water only, or 40 mg frusemide and 8 g activated charcoal with water either immediately or after different time intervals. The diuretic effect of frusemide was totally prevented when taken together with charcoal, but became apparent gradually when charcoal was taken after a lag time. This experiment is simple to carry out and demonstrates vividly the treatment principles of acute intoxications.

Effects of furosemide on blood pressure in anephric rats.

This study has been performed in order to evaluate whether furosemide can induce changes in blood pressure independently of its diuretic effects,and whether its pressor effects are connected with the ability to synthetize renal prostaglandins. The experiments were performed in four groups of volume-expanded rats: the first (n.5) had bilateral ligation of the renal vessels; the second (n.8) had bilateral ligation of the ureters; the third group (n.6) had ureters ligation after pre-treatment with indomethacin; the fourth group (n.2) received a pre-treatment with captopril. After blood pressure stabilization, furosemide was administered i.v. (0.125 mg/100 g. of body weight). Indirect readings of the blood pressure were obtained at 1, 2, 3, 4, 5, 7.5, 10, 15, 20 min. After furosemide administration, blood pressure fell down quickly in the rats with ureteral ligation and in those with captopril pretreatment, while the tensive response to furosemide was blunted by the indomethacin treatment. In conclusion, furosemide can reduce blood pressure by a mechanism non related with its diuretic properties, which, however, requires the integrity of the renal connections with the circulatory system.

Intratubular albumin blunts the response to furosemide-A mechanism for diuretic resistance in the nephrotic syndrome.

An attenuated response to loop diuretics is a frequent observation in the nephrotic syndrome. To determine if the presence of albumin in renal tubular fluid attenuates diuretic response in normal rats, in vivo loop segment microperfusion was performed in normal rats at 20 nl/min with perfusates containing 6.0 microM furosemide in the presence and absence of 3.8 microM albumin. Compared to loop segments perfused without diuretic (control), furosemide reduced (P less than .001) fractional chloride uptake from 56 +/- 2 to 34 +/- 2%. After addition of albumin to furosemide perfusate, fractional loop chloride reabsorption was 45 +/- 1%; a value greater (P less than .01) than that observed in furosemide perfused loop segments, but less (P less than .05) than that observed in control loop segments. Albumin added to perfusate in the absence of furosemide had no effect on fractional loop segment chloride uptake. Addition of 1.7 microM immunoglobulin G to furosemide perfusate failed to attenuate furosemide response. Absolute loop segment chloride reabsorption demonstrated a similar pattern. Tubule fluid perfusion rates determined in vivo and loop segment fluid reabsorption were equivalent in all groups. Thus, albumin in renal tubule fluid attenuates the effect of furosemide on loop segment chloride reabsorption in the rat. This blunted response presumably occurs because of a reduction in the amount of pharmacologically active drug due to albumin-furosemide binding. Consequently, albumin-furosemide binding in the renal tubule may contribute to the diuretic resistance in nephrotic syndrome.

Clinical pharmacological studies of some possible interactions of lornoxicam with other drugs.

A series of studies in human subjects of potential interactions of lornoxicam with some other drugs is reviewed. No evidence of kinetic interaction was found with the antacids Maalox or Solugastrol, nor was there evidence of influence on antipyrine clearance. Lornoxicam reduced warfarin clearance and enhanced its hypoprothrombinaemic effect. It did not influence glibenclamide kinetics, but plasma insulin concentrations were significantly higher and plasma glucose concentrations significantly lower when lornoxicam and glibenclamide were co-administered. Lornoxicam produced a modest reduction in digoxin clearance, but no other clear evidence of interaction was seen. Lornoxicam significantly antagonized the diuretic and natriuretic actions of frusemide.