A bioavailability/bioequivalence and pharmacokinetic study of two oral doses of torasemide (5 and 10 mg): prolonged-release versus the conventional formulation

A Systematic Critical Review of Clinical Pharmacokinetics of Torasemide

PURPOSE

Torasemide is a potassium-sparing loop diuretic used to treat fluid retention associated with congestive heart failure and kidney and hepatic diseases. This systematic review was conducted to combine all accessible data on the pharmacokinetics (PK) of torasemide in healthy and diseased populations, which may help clinicians avert adverse drug reactions and determine the correct dosage regimen.

METHODS

Four databases were systematically searched to screen for studies associated with the PK of torasemide, and 21 studies met the eligibility criteria. The review protocol was registered in the PROSPERO database (CRD42023390178).

RESULTS

A decrease in maximum plasma concentration (C max ) was observed for torasemide after administration of the prolonged-release formulation in comparison to that after administration of the immediate-release formulation, that is, 1.12 ± 0.17 versus 1.6 ± 0.2 mcg/mL. After administering an oral dose of torasemide, a 2-fold increase in the area under the concentration-time curve (AUC) was reported in patients with congestive heart failure compared with the healthy population. Moreover, the patients with renal failure (clearance < 30 mL/min) showed an increase in value of AUC 0-∞ that is, 42.9 versus 8.091 mcg.h -1 .mL -1 compared with healthy subjects. In addition, some studies have reported interactions with different drugs, in which irbesartan showed a slight increase in the AUC 0-∞ of torasemide, whereas losartan and empagliflozin did not.

CONCLUSIONS

The current review summarizes all available PK parameters of torasemide that may be beneficial for avoiding drug-drug interactions in subjects with renal and hepatic dysfunction and for predicting doses in patients with different diseases.

Sodium and Fluid Excretion With Torsemide in Healthy Subjects is Limited by the Short Duration of Diuretic Action

BACKGROUND

Loop diuretics are highly natriuretic but their short duration of action permits postdiuretic sodium retention, which limits salt loss unless dietary salt is severely restricted. We tested the hypothesis that a more prolonged duration of action would enhance salt loss.

METHODS AND RESULTS

Ten healthy participants were crossed over between 20 mg of oral immediate-release or extended-release (ER) torsemide while consuming a fixed diet with 300 mmol·d-1 of Na+. Compared with immediate-release, plasma torsemide after ER was 59% lower at 1 to 3 hours but 97% higher at 8 to 10 hours as a result of a >3-fold prolongation of time to maximal plasma concentrations. The relationship of natriuresis to log torsemide excretion showed marked hysteresis, but participants spent twice as long with effective concentrations of torsemide after ER, thereby enhancing diuretic efficiency. Compared with immediate-release, ER torsemide did not reduce creatinine clearance and increased fluid (1634±385 versus 728±445 mL, P<0.02) and Na+ output (98±15 versus 42±17 mmol, P<0.05) despite an 18% reduction in exposure. Neither formulation increased K+ excretion.

CONCLUSIONS

Torsemide ER prolongs urine drug levels, thereby increasing the time spent with effective drug concentrations, reduces postdiuretic Na+ retention, and moderates a fall in glomerular filtration rate. It caused significant Na+ loss even during very high salt intake. Thus, a short duration of action limits salt loss with loop diuretics. These conclusions warrant testing in subjects with edema and heart failure.

The impact of torasemide on haemodynamic and neurohormonal stress, and cardiac remodelling in heart failure - TORNADO: a study protocol for a randomized controlled trial

BACKGROUND

Approximately 50% of heart failure patients are readmitted to hospital within 6 months, owing to deterioration of their condition. Thus, symptomatic treatment of heart failure requires significant improvement. The aim of this study is to compare the effects of torasemide and furosemide on biochemical parameters of haemodynamic and neurohormonal compensation, myocardial remodelling, clinical outcomes and quality of life in patients with chronic heart failure.

METHODS

This is a multicentre, randomized, open, blinded endpoint phase-IV trial. The study includes 120 heart failure patients in NYHA (New York Heart Association) functional class II-IV, treated with optimal heart failure therapy, with indications for use of loop diuretics. At enrolment, patients are stable, with a fixed dose of loop diuretics. Patients are randomized to treatment with furosemide or torasemide (randomization 1:1). After randomization, the current fixed dose of furosemide is continued or is replaced by an equipotential dose of torasemide (4:1). The study consists of two control visits (3 and 6 months after enrolment) with minimal follow-up of 6 months. Assessment involves clinical examination, Quality of Life Questionnaire, laboratory tests, echocardiography, electrocardiography, 24 h Holter-electrocardiography monitoring, 6 -min walk test and assessment of fluid retention. Any need for dose adjustment is assessed during the observation. The primary objective is to compare the effects of torasemide and furosemide on clinical and biochemical parameters of haemodynamic and neurohormonal compensation and myocardial remodelling. Secondary objectives include monitoring of: changes in signs and symptoms of heart failure, NYHA functional class, quality of life, dosage changes, rate of readmissions and mortality.

DISCUSSION

Despite decades of the diuretic's history, knowledge about diuretic therapy is still unsatisfactory. The most widely used diuretic, furosemide, has a stormy pharmacokinetics and pharmacodynamics, and is associated with a high risk of mortality and hospitalization for worsening heart failure. Reports are very encouraging and suggest beneficial effects of torasemide. Hence, there is a need for further studies of the overall effect of torasemide, compared with furosemide. This can translate into improved quality of life and better prognosis of patients with heart failure.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01942109 . Registered on 24 August 2013.

Randomized, open-label, blinded-endpoint, crossover, single-dose study to compare the pharmacodynamics of torasemide-PR 10 mg, torasemide-IR 10 mg, and furosemide-IR 40 mg, in patients with chronic heart failure

Purpose

Diuretics are the primary treatment for the management of chronic heart failure (HF) symptoms and for the improvement of acute HF symptoms. The rate of delivery to the site of action has been suggested to affect diuretic pharmacodynamics. The main objective of this clinical trial was to explore whether a prolonged release tablet formulation of torasemide (torasemide-PR) was more natriuretically efficient in patients with chronic HF compared to immediate-release furosemide (furosemide-IR) after a single-dose administration. Moreover, the pharmacokinetics of torasemide-PR, furosemide-IR, and torasemide-IR were assessed in chronic HF patients as well as urine pharmacodynamics.

Methods

Randomized, open-label, blinded-endpoint, crossover, and single-dose Phase I clinical trial with three experimental periods. Torasemide-PR and furosemide-IR were administered as a single dose in a crossover fashion for the first two periods, and torasemide-IR 10 mg was administered for the third period. Blood and urine samples were collected at fixed timepoints. The primary endpoint was the natriuretic efficiency after administration of torasemide-PR and furosemide-IR, defined as the ratio between the average drug-induced natriuresis and the average drug recovered in urine over 24 hours.

Results

Ten patients were included and nine completed the study. Here, we present the results from nine patients. Torasemide-PR was more natriuretically efficient than furosemide-IR (0.096±0.03 mmol/μg vs 0.015±0.0007 mmol/μg; P<0.0001). Mictional urgency was lower and more delayed with torasemide-PR than with furosemide-IR.

Conclusion

In a study with a limited sample size, our results suggest that 10 mg of torasemide-PR is more natriuretically efficient than 40 mg of furosemide-IR after single-dose administration in patients with chronic HF over a 24-hour collection period. Further studies are necessary to evaluate potential pharmacodynamic differences between torasemide formulations and to assess its impact on clinical therapeutics.

TORAFIC study protocol: torasemide prolonged release versus furosemide in patients with chronic heart failure

Loop diuretics, such as torasemide and furosemide, are important agents in the treatment of chronic heart failure. Beneficial effects of torasemide immediate-release formulation beyond diuresis have been documented as the ability of this compound to inhibit myocardial synthesis and deposition of collagen type I in patients with chronic heart failure. In addition, torasemide-treated patients, but not furosemide-treated patients, showed decreased serum concentrations of the C-terminal propeptide of procollagen type I, a biochemical marker of myocardial fibrosis. The aim of the TORAFIC study is to test the efficacy of torasemide prolonged-release formulation (PR) in reducing myocardial fibrosis in chronic heart failure in a large, randomized clinical trial.

METHODS

This prospective, Phase IV, randomized, blinded end point, active-controlled clinical trial will randomize 142 patients with chronic heart failure in New York Heart Association functional class II-IV to 8 months treatment with either torasemide-PR (10-40 mg daily) or furosemide (40-160 mg daily). The primary objective is to test the hypothesis that torasemide-PR is superior to furosemide in reducing myocardial fibrosis. The primary outcome measure is the difference in the change of serum propeptide of procollagen type I concentration from the initial to the final visit between both study groups. Secondary outcome measures include all efficacy variables related to heart failure (signs and symptoms, ECG, echocardiogram and serum levels of N-terminal brain natriuretic propeptide). Secondary safety variables are heart rate, blood pressure, laboratory data, adverse events, cardiovascular events (hospital admission, emergency department visits) and quality of life (Minnesota questionnaire).

DISCUSSION

This trial will test whether torasemide-PR possesses antifibrotic properties, which may provide an additional benefit beyond diuresis in patients with chronic heart failure.