Tolerance of torasemide in cats with congestive heart failure: a retrospective study on 21 cases (2016–2019)

Abstract

Background In dogs with congestive heart failure (CHF), the efficacy of torasemide, a loop diuretic, has been demonstrated. However, unlike in dogs and humans little has been described about the use of torasemide in the cat with spontaneous CHF. The objectives of this retrospective study were therefore to describe the therapeutic use of oral torasemide in cats with spontaneous CHF, document its potential adverse effects while reporting the clinical course of this feline population following torasemide administration in addition to standard medical therapy. Results Medical records of 21 client-owned cats with CHF (median age = 10.6 years [interquartile range (IQR) = 6.5–11.2]) receiving torasemide were reviewed. Data collected included torasemide dosages, other concurrent medications, physical examination features, echocardiographic data, and potential adverse effects during follow-up. A survival analysis was performed to estimate the time from diagnosis to cardiac death. Dyspnea related to CHF was identified in all cats (pleural effusion [8/21], pulmonary edema [5/21] or both [8/21]), associated with ascites in 4/21 cats. The CHF cause was determined by echocardiography in all cats: hypertrophic (n = 10), restrictive (n = 6), arrhythmogenic right ventricular (n = 3), dilated (n = 1) cardiomyopathies, and aortic valve abnormality (n = 1). At initiation, median torasemide dosage was 0.21 mg/kg [IQR = 0.17–0.23] q24h. Clinical signs declined in most cats (20/21) during the first 2 weeks with no remarkable adverse events. Median survival time after torasemide prescription was 182 days [IQR = 46–330]. A contemporary control group including 54 cats with CHF, receiving furosemide as sole loop diuretic treatment was compared with the study group. Median (IQR) survival time of cats in the control group was not significatively different (p = 0.962) from that of the torasemide group, i.e., 148 days (9–364), although the torasemide group included significantly more cats with recurrent episodes of CHF (52%) that the control group (19%). Conclusions This case series demonstrates that torasemide can be used in cats with spontaneous CHF. This therapeutic interest needs to be confirmed by prospective clinical trials.

The Feline Cardiomyopathies: 2. Hypertrophic cardiomyopathy

“…The initial dosage for torsemide is typically in the range of 0.1-0.3 mg/kg Po q24h. 183 A cat in stage d heart failure is refractory to furosemide administration, meaning clinical signs (eg, elevated sleeping RR [tachypnea], dyspnea) are persisting despite treatment. A cat that is not responding adequately to high-dose furosemide Po may not be responding because not enough drug is getting to the nephron due to poor bioavailability (poor absorption from the Gi tract).…”

Pharmacokinetic and pharmacodynamic properties of orally administered torasemide in healthy cats

“…Any change in the health status of the animals (eg, renal or liver impairment) could alter the obtained pharmacokinetic parameters. Interestingly, this dosage is very similar to the PO dosage selected in another study aiming at assessing the effects of torasemide in cats (0.3 mg/kg) 3 as well as the mean starting dosage of 0.21 mg/kg in a retrospective case series of cats in CHF 20 …”

“…Interestingly, this dosage is very similar to the PO dosage selected in another study aiming at assessing the effects of torasemide in cats (0.3 mg/kg) 3 as well as the mean starting dosage of 0.21 mg/kg in a retrospective case series of cats in CHF. 20 Notably, no severe adverse effects were observed after the single administration of torasemide to healthy cats, up to 0.4 mg/kg PO. No significant effect of torasemide administration on pCr or blood pressure was noted.…”

“…3 A recent retrospective study identified good tolerability of torasemide in cats with spontaneous CHF at a median dosage of up to 0.29 mg/kg q24h (range, 0.16-0.40). 20 Nevertheless, fundamental data on the basic pharmacological properties of torasemide in cats still is lacking, and is essential for the design of prospective clinical trials in this species. Thus, our objectives were to assess the pharmacokinetic and pharmacodynamic parameters of torasemide in healthy cats and to study the effects of a single administration of torasemide on indicators of diuresis, plasma creatinine concentration, blood pressure, electrolyte concentrations, and markers of RAAS activation.…”

“…A previous study concluded that the diuretic effect of torasemide peaked 4 hours after administration (vs 2 hours with furosemide) and persisted for 12 hours (vs 6 hours) in cats with experimentally‐induced left ventricular hypertrophy 3 . A recent retrospective study identified good tolerability of torasemide in cats with spontaneous CHF at a median dosage of up to 0.29 mg/kg q24h (range, 0.16‐0.40) 20 . Nevertheless, fundamental data on the basic pharmacological properties of torasemide in cats still is lacking, and is essential for the design of prospective clinical trials in this species.…”