Clinical toxicity of furosemide in hospitalized patients. A report from the Boston Collaborative Drug Surveillance Program

Contribution of Uptake and Efflux Transporters to Oral Pharmacokinetics of Furosemide

Furosemide is a widely used diuretic for treating excessive fluid accumulation caused by disease conditions like heart failure and liver cirrhosis. Furosemide tablet formulation exhibits variable pharmacokinetics (PK) with bioavailability ranging from 10 to almost 100%. To explain the variable absorption, we integrated the physicochemical, in vitro dissolution, permeability, distribution, and the elimination parameters of furosemide in a physiologically-based pharmacokinetic (PBPK) model. Although the intravenous PBPK model reasonably described the observed in vivo PK data, the reported low passive permeability failed to capture the observed data after oral administration. To mechanistically justify this discrepancy, we hypothesized that transporter-mediated uptake contributes to the oral absorption of furosemide in conjunction with passive permeability. Our in vitro results confirmed that furosemide is a substrate of intestinal breast cancer resistance protein (BCRP), multidrug resistance-associated protein 4 (MRP4), and organic anion transporting polypeptide 2B1 (OATP2B1), but it is not a substrate of P-glycoprotein (P-gp) and MRP2. We then estimated the net transporter-mediated intestinal uptake and integrated it into the PBPK model under both fasting and fed conditions. Our in vitro data and PBPK model suggest that the absorption of furosemide is permeability-limited, and OATP2B1 and MRP4 are important for its permeability across intestinal membrane. Further, as furosemide has been proposed as a probe substrate of renal organic anion transporters (OATs) for assessing clinical drug-drug interactions (DDIs) during drug development, the confounding effects of intestinal transporters identified in this study on furosemide PK should be considered in the clinical transporter DDI studies.

Is Inhaled Furosemide a Potential Therapeutic for COVID-19?

The potentially lethal infection caused by the novel Severe Acute Respiratory Disease Coronavirus-2 (SARS-CoV-2) has evolved into a global crisis. Following the initial viral infection is the host inflammatory response that frequently results in excessive secretion of inflammatory cytokines (e.g., IL-6 and TNFα), developing into a self-targeting, toxic "cytokine storm" causing critical pulmonary tissue damage. The need for a therapeutic that is available immediately is growing daily but the de novo development of a vaccine may take years. Therefore, repurposing of approved drugs offers a promising approach to address this urgent need. Inhaled furosemide, a small molecule capable of inhibiting IL-6 and TNFα, may be an agent capable of treating the Coronavirus Disease 2019 cytokine storm in both resource-rich and developing countries. Furosemide is a "repurpose-able" small molecule therapeutics, that is safe, easily synthesized, handled, and stored, and is available in reasonable quantities worldwide.

Real-world evidence for the safety of ipragliflozin in elderly Japanese patients with type 2 diabetes mellitus (STELLA-ELDER): final results of a post-marketing surveillance study

OBJECTIVE

To investigate the real-world safety of ipragliflozin in elderly Japanese patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

Japanese patients (≥65 years old) who were first prescribed ipragliflozin within 3 months after its launch in April 2014 were registered in this post-marketing surveillance (PMS). Final data collection was in July 2015. Survey items included demographics, treatments, adverse drug reactions (ADRs), vital signs, and laboratory variables.

RESULTS

The PMS included 8505 patients (4181 males/4324 females). The mean age and diabetes duration were 72.3 years and 10.6 years, respectively. In 84.3% of patients, ipragliflozin was prescribed at 50 mg/day, which was continued unchanged. Overall, 16.91% of patients experienced 1880 ADRs, and 165 ADRs were classified as serious in 127 patients (1.49%). ADRs of special interest included skin complications, volume depletion, polyuria/pollakiuria, genital infection, urinary tract infection, renal disorders, hypoglycemia, cerebrovascular disease, cardiovascular disease, malignant tumor, fracture, and ketone body-related events.

CONCLUSIONS

This 1-year PMS revealed probable ADRs in elderly Japanese patients with T2DM prescribed ipragliflozin in real-world settings, with no new safety concerns. The risk factors for ADRs varied but could be rationalized. The results should help physicians to identify possible treatment-emergent ADRs in ipragliflozin-treated patients.

Prophylactic furosemide treatment in acute myocardial infarction

Prophylactic diuretic therapy in acute myocardial infarction (AMI) was evaluated in 83 consecutive patients without severe left ventricular failure (LVF) on admission. A high dose group (HDG) received 120-160 mg and a low dose group (LDG) 20-40 mg furosemide daily for six weeks. Mortality and reinfarction rates did not differ between the groups. One HDG patient and five LDG patients developed severe LVF. Four HDG patients developed severe dehydration. Serum enzyme activities and electrolytes were similar in both groups. The increased diuresis in the HDG was accompanied by a 4% hemoconcentration, smaller radiological heart volumes, higher heart rates, a higher demand for nitroglycerin and higher ratings of thirst. Exercise tests yielded similar results in both groups. Later blood volumes and transthoracic electrical impedance were similar in both groups. It is concluded that liberal prophylactic furosemide treatment in AMI offers no major clinical advantage.

[Is thiamine supplementation necessary in patient with cardiac insufficiency?]

Interest has recently risen regarding thiamine deficiency in patients with cardiac deficiency who are receiving long-term diuretic therapy. Thiamine deficiency can lead biventricular myocardial failure (cardiac beriberi), and treatment consists of thiamine administration. Studies have shown that long-term furosemide use may be associated with thiamine deficiency through urinary loss, contributing to cardiac insufficiency in patients with congestive heart failure. Thiamine supplementation could improved left ventricular function. However, the results of those studies are controversial, and none study have till proved the clinical impact of a systematic administration of thiamine in a cohort of patients with cardiac insufficiency. To date, and waiting for available literature, thiamine administration should be consider in patients at risk for thiamine deficiency (elderly, malnourished, alcoholic), and in patients receiving very large doses of diuretics.

Furosemide-associated fever

We describe a 5-month-old infant who had fever of unknown origin leading to an exhaustive evaluation during a 7-week period. Fever caused by the use of furosemide was proved; the fever resolved after discontinuation of this medication and recurred after its reintroduction.

Possible severe thrombocytopenia associated with a single dose of plicamycin

OBJECTIVE

To report a case of possible severe thrombocytopenia associated with administration of a single dose of plicamycin.

CASE SUMMARY

A 73-year-old man with prostate cancer was admitted to the hospital with hypercalcemia (total serum calcium concentration 4.02 mmol/L) and a low baseline platelet count (152 x 10(9)/L). Because of his symptomatic hypercalcemia, he was treated with NaCl 0.9%, furosemide, oral inorganic phosphate, and a single dose of plicamycin (15 micrograms/kg). Five days after plicamycin administration his platelet count decreased to 52 x 10(9)/L, and continued to decrease further even after the transfusion of four units of platelets to a nadir of 7 x 10(9)/L (hospital day 20). A second transfusion produced a small increase in his platelet count. The patient's clinical status continued to deteriorate, however, and he subsequently died.

DISCUSSION

Plicamycin and other drugs that may induce thrombocytopenia are reviewed. The time course between plicamycin administration and the development of thrombocytopenia in our patient is assessed. Other contributing factors such as a low baseline platelet count and advanced age are also addressed.

CONCLUSIONS

It is likely that the severe thrombocytopenia experienced by our patient was caused by a single dose of plicamycin. Adjusting the dosage for a patient's renal function as well as close monitoring of the platelet count are necessary when administering this drug. We report this case to remind clinicians of the potential for the development of severe thrombocytopenia following administration of a single dose of plicamycin.

Drug-induced diabetes

The only drugs which commonly cause diabetes during therapeutic use are the anti-hypertensive vasodilator diazoxide, and corticosteroids in high doses such as those used to palliate intracranial tumours. Thiazide diuretics have in the past been used in higher doses than necessary to treat hypertension, and the lower doses now used probably carry only a slight risk of inducing diabetes. The risk from beta-blockers is also quite small, but there is some evidence that thiazides combined with beta-blockers may be more likely to cause diabetes than either drug alone. The combination is probably best avoided in patients with a family history of non-insulin-dependent diabetes. The effect of the low-oestrogen combined oral contraceptive pill seems to be slight, and it presents a risk only to women who have had gestational diabetes. Bodybuilders who take enormous doses of anabolic-androgens can develop impaired glucose tolerance. Several drugs, including theophylline, aspirin, isoniazid and nalidixic acid can cause transient hyperglycaemia in overdosage, but only streptozotocin, alloxan and the rodenticide Vacor are likely to cause permanent diabetes.

Thiamine deficiency in patients with congestive heart failure receiving long-term furosemide therapy: a pilot study

PURPOSE

To test the hypothesis that long-term furosemide therapy in patients with congestive heart failure (CHF) is associated with clinically significant thiamine deficiency via urinary loss.

DESIGN

(1) Biochemical evaluation of thiamine status in hospitalized patients with CHF treated with long-term furosemide and in age-matched control patients. (2) Uncontrolled trial of the effect of intravenous thiamine on cardiac performance in a subset of six patients with CHF.

SETTING

General medical ward of a teaching community hospital.

PATIENTS

Twenty-three patients with chronic CHF receiving furosemide, and 16 age-matched control patients without heart failure and not taking diuretics. Daily furosemide doses were 80 to 240 mg, and duration of furosemide therapy was 3 to 14 months. Patients with identifiable causes of inadequate thiamine intake, absorption, or utilization or increased metabolic requirements were excluded.

INTERVENTION

A 7-day course of intravenous thiamine, 100 mg twice daily, in six consenting patients with CHF.

RESULTS

A high thiamine pyrophosphate effect (TPPE), indicating thiamine deficiency, was found in 21 of 23 furosemide-treated patients and in two of 16 controls (p less than 0.001). The mean (+/- SE) TPPE (normal: 0% to 15%) in furosemide-treated and control patients was 27.7 +/- 2.5% and 7.1 +/- 1.6%, respectively (p less than 0.001). Despite the high TPPE, the mean (+/- SE) urinary thiamine excretion in the furosemide-treated patients (n = 18) was inappropriately high (defined as greater than 130 micrograms/g creatinine), 410 +/- 95 micrograms/g creatinine, even in comparison with that in the controls (n = 14): 236 +/- 69 micrograms/g creatinine. In six patients treated with intravenous thiamine, the elevated TPPE decreased to normal, from a mean (+/- SE) of 27.0 +/- 3.8% to 4.5 +/- 1.3% (p less than 0.001), indicating normal thiamine utilization capacity. Left ventricular ejection fraction increased in four of five of these patients studied by echocardiography.

CONCLUSIONS

These preliminary findings suggest that long-term furosemide therapy may be associated with clinically significant thiamine deficiency due to urinary loss and contribute to impaired cardiac performance in patients with CHF. This deficit may be prevented or corrected by appropriate thiamine supplements.

Lack of a modifying effect by the diuretic drug furosemide on the development of neoplastic lesions in rat two-stage urinary bladder carcinogenesis

The effect of the diuretic drug furosemide on two-stage urinary bladder carcinogenesis in F344 rats initiated by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was investigated with regard to possible promoting activity. BBN was administered at 2 doses, 0.01 or 0.05%, in drinking water for 4 wk, and thereafter furosemide was given by gavage 3 times weekly for 32 wk, 250 mg/kg body weight. Furosemide ingestion induced diuresis with an alkaline, hypotonic urine. No significant difference with regard to incidences of bladder lesions were apparent between furosemide and control groups. The present investigation indicated that neither furosemide nor its related polyuria acted as a promoter in two-stage urinary bladder carcinogenesis.

A decade of developments in diuretic drug therapy

New diuretics introduced into clinical medicine during the past decade include potent new loop diuretics such as bumetanide and piretanide, the uricosuric indanyloxyacetic acid derivative indacrinone, and a new generation of sulfamoyl diuretics such as indapamide and xipamide, which are recommended primarily for the treatment of hypertension. Pharmacokinetic studies of individual diuretics have demonstrated that the diuretic and natriuretic responses to the newer agents generally follow the plasma drug concentration-time curves and urinary drug excretion rates. Therapeutic monitoring can therefore be achieved in most patients with edema or hypertension by close clinical observation and laboratory analysis of plasma electrolyte and creatinine concentrations and urinary electrolyte excretion rates. Interest in the mechanisms involved in the renal and extrarenal vascular actions of the newer diuretics has led to a better understanding of how changes in venous compliance, peripheral vascular resistance, and renal blood flow distribution may contribute to the overall therapeutic response to these agents, especially in patients with severe congestive heart failure, renal insufficiency with low glomerular filtration rates, and hypertension with cardiorenal complications. Adverse reactions to modern diuretics, which are mainly an extension of their renal pharmacodynamic effects, have proved to be minimal, provided that the dosage is adjusted to meet but not exceed individual patient requirements. However, the long-term consequences of prolonged periods of diuretic-induced alterations in plasma potassium levels, and metabolic effects that include elevated blood lipids, are still under investigation.

Potassium and the heart

The electrical stability of the heart is more sensitive to the extracellular than to the intracellular potassium concentration. During exercise, extracellular potassium varies rapidly. Catecholamines also modulate the plasma potassium concentration. Hypokalaemia of any cause can precipitate arrhythmias. Ischaemic myocardium loses potassium into the extracellular space within seconds and the cell becomes depolarized. The rise of the extracellular potassium ion concentration accounts for many of the early electrophysiological changes. Abrupt changes of plasma potassium concentration in normal myocardium and a high potassium concentration in ischaemic myocardium can set up electrical forces which initiate arrhythmias. The same phenomenon can account for changes on the electrocardiogram early after the cessation of an exercise test in a patient with ischaemic heart disease. Accumulation of potassium between cells in response to an increase of heart rate is a possible mechanism for false positive exercise tests and Syndrome X.

Diuresis with continuous infusion of furosemide after cardiac surgery

We prospectively evaluated the diuretic effect of furosemide administered by bolus injection and by continuous infusion in 18 cardiac surgery patients. Nine patients were randomly assigned to receive 0.3 mg/kg of furosemide as a bolus injection at time 0 and again 6 hours later (nine patients) or 0.05 mg/kg per hour of furosemide as a constant infusion for 12 hours (nine patients). There were no significant differences between groups with respect to age, weight, creatinine clearance, changes in serum sodium and potassium levels, total urinary concentrations of sodium and potassium, or total urine volume for 12 hours. Diuresis during continuous infusion of furosemide was less variable from hour to hour than after bolus injection of furosemide and was sustained throughout the infusion period. Although the continuous infusion of furosemide will not provide the rapid and vigorous diuresis that is necessary in some clinical situations, it may be useful whenever a gentle, sustained diuresis is desired.

Diuretic withdrawal--a need for caution

Diuretic therapy was withdrawn from 42 patients receiving modest drug doses for reasons other than hypertension, active heart failure and renal or hepatic oedema, with frequent assessment by clinical, biochemical and radiological methods for 12 weeks. Of 38 patients who could have completed the study, 27 (71%) did so without ill-effect. Eleven (29%) patients deteriorated clinically or radiologically, 7 within 2 weeks of discontinuing diuretics, and 1 of them died after acute pulmonary oedema and a haematemesis, despite intensive resuscitation. The outcome of drug withdrawal could be predicted in 35 of the patients using a multifactorial discriminant analysis but individual parameters had poor predictive value. The lack of demonstrable benefit in many patients and the incidence of adverse effects associated with long-term diuretic therapy suggest that withdrawal should be considered more often in this type of patient. However, there is a need for caution in this situation and withdrawal should only be attempted if close medical supervision and radiological examination of the chest are possible.

Drug attributed alterations in potassium handling in congestive cardiac failure

Information from a comprehensive drug surveillance programme has been reviewed to give details of the frequency of drug-related hypo- and hyperkalaemia in a group of 3879 patients admitted to hospital with cardiac failure. Hypokalaemia was commoner in females, was unrelated to blood area concentration on admission and was twice as common amongst recipients of potassium-losing diuretics who did not take potassium supplements than amongst those who received potassium retaining diuretics. By contrast hyperkalaemia was strongly related to blood urea concentration on admission. It was also related to in-hospital diuretic therapy; being thrice as frequent amongst recipients of aldosterone antagonists than amongst those receiving potassium-losing diuretics without additional supplements. Life-threatening hypo- and hyper-kalaemia were rare in this group of patients with heart failure, occurring with approximately equal frequencies of about 2 per 1000 patients treated.

Effects of loop diuretics on carbohydrate metabolism and electrolyte excretion

The effects of two loop diuretics, bumetanide and furosemide, on carbohydrate metabolism and electrolyte balance were assessed in 11 normal male subjects in a double-blind manner. Glucose, insulin, glucagon, and growth hormone responses to 5-hour glucose tolerance test and arginine infusion were measured during the control and drug treatment periods. Three other non-insulin-dependent diabetic subjects, receiving diuretic drug for six weeks, underwent a similar protocol. Kaliuresis and natriuresis due to diuretic administration were significant only on day 1 of treatment. There were no significant changes in total body potassium by 40K counting; net potassium loss by balance study was minimal in both the acutely treated subjects and the chronically treated patients. Effects of bumetanide and furosemide on water and electrolyte excretion did not differ. Glucose tolerance was significantly improved with bumetanide but not with furosemide. Plasma insulin, glucagon, and growth hormone levels during the oral glucose tolerance test were unaffected by either drug. Insulin levels with arginine infusion were significantly increased, and growth hormone levels decreased with bumetanide but not with furosemide. No evidence of impaired carbohydrate metabolism in the three chronically treated diabetic subjects was seen. It is concluded that the effects of bumetanide and furosemide on potassium balance and glucose utilization were minimal in this experimental setting.

Diuretics and the institutional elderly: a case against routine potassium prescribing

In 14 elderly male residents of a veterans' care complex who were receiving diuretic therapy for cardiac failure, oral potassium (K) supplements were withdrawn. Plasma and erythrocyte K levels were measured immediately before and six weeks after withdrawal of the supplements (38 mEq K daily). The controls comprised 19 elderly residents without disease and not taking drugs likely to influence K status. Study subjects and controls were receiving the same diet (average daily K content 100 mEq). After withdrawal of K supplements, the mean plasma K level fell significantly but the mean erythrocyte K level remained unchanged and did not differ from the control values. For a further six weeks after the withdrawal period, 7 subjects were treated with Aldactazide (diuretic hydrochlorothiazide plus K-sparing spironolactone). The plasma K level increased significantly but the erythrocyte K level remained unchanged. It was concluded that, in this setting, diuretic-induced hypokalemia is not necessarily accompanied by intracellular K depletion and that routine prophylaxis with K supplements or K-sparing agents is unnecessary and not without risk. Such therapy should be reserved for patients considered at special risk of K depletion because of known poor dietary intake, advanced liver disease, secondary hyperaldosteronism with renovascular hypertension, gastrointestinal losses, or nondiuretic medication known to affect K status adversely.

Fixed-dose combination diuretics in congestive heart failure: an evaluation

Thirty-two patients with congestive heart failure were studied for their clinical and biochemical responses to the administration of two combination diuretic products (hydrochlorothiazide/spironolactone and hydrochlorothiazide/triamterene) and the single entity diuretic furosemide. Data from these studies revealed the following: 1. Comparison of the patients on furosemide with those receiving the combination products showed no difference in serum potassium or 24-hour potassium excretion. 2. Significant changes in blood urea nitrogen, plasma renin activity, and urinary aldosterone excretion were noted with both fixed-combination medications but not with furosemide. 3. The combination diuretics offered no clinical benefits over the single agent furosemide. 4. Therapy is best served by the use of a single effective diuretic agent for the treatment of most patients with congestive heart failure.

Effect of furosemide on serum clearance and renal excretion of digoxin

Serum turnover and urinary excretion of digoxin with or without oral furosemide were studied in six healthy subjects who received 0.006 mg/kg body weight digoxin intravenously. During furosemide treatment, the total amount of urinary digoxin did not change but the digoxin clearance during the diuretic phase and the digoxin excretion after the diuresis decreased significantly. The average serum half-life was prolonged from 37 hours in the control period to 86 hours in the furosemide period. Decreased glomerular filtration rate by volume depletion might have been responsible for the decreased excretion of digoxin, but there was no significant difference in urine volume after diuresis between the two periods, suggesting the possibility of inhibition of tubular secretion of digoxin by furosemide. It is also possible that serum digoxin concentration may be elevated if furosemide were given more frequently.

Continuous infusion of frusemide in refractory oedema

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Effects of hydration on gentamicin excretion and renal accumulation in furosemide-treated rats

The effect of furosemide on gentamicin excretion and tissue accumulation was studied with clearance techniques in anesthetized rats, at two different infusion rates of saline or Ringer solution. Gentamicin ( approximately 20 mg/kg) was administered by constant intravenous infusion over a period of 3 h. With the low fluid infusion rate, furosemide (25 mg/kg intravenously) caused severe reduction in glomerular filtration rate and diminished urinary output of gentamicin. Serum and renal tissue levels of the antibiotic were significantly elevated. High fluid infusion prevented the decline of the glomerular filtration rate, with near normalization of all measurements. A fluid deficit incurred by furosemide was noted at both the low and high infusion rates. Complete correction of this fluid deficit by continuous adjustment of the infusion rate fully restored normal renal handling of gentamicin. These results suggest that furosemide had no direct effect on renal excretion of gentamicin. In comparison, renal handling of gentamicin in rats did not respond to changes in the rate of fluid infusion in the absence of furosemide therapy. It appears that gentamicin excretion and gentamicin accumulation in the renal cortex in furosemide-treated rats, in contrast with those in untreated rats, are influenced significantly by the rate of fluid infusion. Fluid administration sufficient to maintain the glomerular filtration rate was found to be necessary for appropriate gentamicin elimination, with consequent reduction in serum and renal tissue levels of the drug.