Clinical pharmacy of torsemide: toxicity and safety considerations in elderly patients – with an embedded case report

Shirlin M.S1*, Vignesh R1, Johnson A2

1Clinical pharmacist, Kauvery Hospital , Heartcity, Trichy, Tamil Nadu

2Group Clinical pharmacist, Kauvery Hospital, Heart city, Trichy, Tamil Nadu

*Correspondence

Abstract

Torsemide, a long-acting loop diuretic, is widely used in the management of fluid overload states such as heart failure and chronic kidney disease. Although clinically effective, its use in elderly patients requires careful clinical pharmacy oversight due to altered pharmacokinetics, multimorbidity, and high susceptibility to adverse drug reactions. This article reviews the clinical pharmacology and toxicity profile of torsemide in older adults, integrating a real-world case scenario that highlights the risks associated with high-dose exposure in a frail geriatric patient.

Key words: Torsemide; CABG

Case Presentation

An 81-year-old male patient with multiple comorbidities including diabetes mellitus, chronic kidney disease stage 4, hyponatremic, hypokalemic, benign prostatic hyperplasia, triple vessel coronary artery disease status post CABG (2016), hypothyroidism, and severe biventricular heart failure with poor left ventricular function presented with suspected complete heart block. He initially presented to an outside clinic with abdominal distension, shortness of breath, reduced urine output, insomnia, fatigue, and loss of appetite for five days. Examination revealed generalized anasarca and massive bilateral lower limb edema, consistent with severe fluid overload. He received treatment with piperacillin–tazobactam, meropenem, and supportive therapy. Despite initial management, significant congestion persisted. On admission to our emergency department, high-dose torsemide therapy was noted in the discharge prescription, with the patient receiving torsemide 200 mg twice daily (total 400 mg/day). This dose exceeded commonly recommended maximum dosing limits and raised immediate clinical concern for diuretic-related toxicity in the setting of advanced CKD and severe heart failure.

Clinical Pharmacology of Torsemide

Loop diuretics are essential agents in the management of volume overload associated with heart failure, renal dysfunction, and hepatic disease. Torsemide is increasingly preferred over other loop diuretics due to its high oral bioavailability, longer half-life, and predictable pharmacokinetic profile. Torsemide acts by inhibiting the Na⁺-K⁺-2Cl⁻ co-transporter in the thick ascending limb of the loop of Henle, leading to increased excretion of sodium, chloride, water, magnesium, and calcium.

Dose Considerations

  • Maximum effective single oral dose: 50–100 mg
  • Maximum recommended total daily dose: 200 mg (usually divided)

Dosing in Altered kidney function

  • eGFR >30 mL/minute/1.73 m : No dosage adjustment necessary.
  • eGFR ≤30 mL/minute/1.73 m : Higher doses may be required to achieve desired diuretic response due to decreased secretion into the tubular fluid. However, single doses >50 to 100 mg are unlikely to result in additional diuretic effect

Beyond this threshold, diuretic response plateaus while toxicity risk increases significantly.

Warning and precautions

Older Adult

  • Beers Criteria: Diuretics are identified in the Beers Criteria as potentially inappropriate medications to be used with caution in patients 65 years and older due to the potential to cause or exacerbate syndrome of inappropriate antidiuretic hormone secretion (SIADH) or; monitor sodium concentration closely when initiating or adjusting the dose in older adults.
  • Diuretic resistance:For some patients, despite high doses of loop diuretic, an adequate diuretic response cannot be attained. Diuretic resistance may be overcome by intravenous rather than oral administration, the use of two diuretics together (eg, a loop diuretic in combination with a thiazide diuretic). When multiple diuretics are used, serum electrolytes need to be monitored even more closely.

Adverse Effects in Elderly Patients

  • Electrolyte imbalance (hyponatremia, hypokalemia, hypomagnesemia)
  • Acute kidney injury due to volume depletion
  • Ototoxicity (tinnitus, reversible hearing loss)
  • Orthostatic hypotension and fall risk
  • Rare severe hypersensitivity reactions

Clinical Pharmacy Discussion

This case highlights several important clinical pharmacy concerns relevant to the safe use of loop diuretics in elderly patients with advanced cardiorenal disease.

High-dose torsemide exposure

The patient was discharged on torsemide 200 mg twice daily (total daily dose: 400 mg/day), which exceeds the commonly recommended maximum daily dose of 200 mg. Although torsemide exhibits a ceiling effect in its natriuretic response, dose escalation beyond this range is associated with a disproportionate increase in toxicity rather than additional clinical benefit.

Such high-dose exposure places the patient at significant risk of:

  • Severe electrolyte disturbances, including hyponatremia, hypokalemia, and hypomagnesemia
  • Progressive renal dysfunction due to intravascular volume depletion
  • Ototoxicity, especially in CKD
  • Profound hypovolemia leading to hemodynamic instability

High-risk patient profile

The patient represented a markedly high-risk clinical profile for loop diuretic–associated toxicity due to multiple compounding factors:

  • Advanced age (81 years)
  • CKD stage 4, resulting in impaired drug clearance and altered pharmacodynamics
  • Severe biventricular heart failure with poor left ventricular function
  • Suspected complete heart block, increasing vulnerability to electrolyte-induced conduction disturbances
  • Recent acute illness with infection and systemic decompensation

The coexistence of these conditions significantly narrows the therapeutic margin of loop diuretic therapy.

Risk of cardiorenal deterioration

In patients with advanced heart failure and chronic kidney disease, excessive loop diuretic dosing may precipitate or exacerbate cardiorenal syndrome. High-dose torsemide in this context may result in:

  • Further reduction in renal perfusion
  • Worsening of cardiorenal syndrome
  • Hemodynamic instability, including hypotension
  • Increased risk of adverse cardiovascular outcomes, including arrhythmias and potential mortality

Clinical Pharmacy Assessment

The patient’s presentation underscores the importance of clinical pharmacy involvement in:

  • Medication reconciliation at transitions of care
  • Dose appropriateness evaluation in renal impairment and heart failure
  • Early identification of high-risk prescriptions
  • Prevention of loop diuretic overuse in frail elderly patients

Discussion and Conclusion

This case highlights a key principle in clinical pharmacy practice: loop diuretics must be carefully titrated in elderly patients with cardiorenal syndrome. Although torsemide has a defined ceiling effect for diuresis, exceeding recommended doses primarily increases toxicity risk rather than improving clinical outcomes.

Medication errors or inappropriate dose escalation at discharge can significantly impact patient safety, particularly in those with CKD stage 4 and advanced heart failure. Structured medication review processes and pharmacist-led interventions are essential in reducing preventable adverse drug events.

In conclusion, Torsemide remains an effective loop diuretic; however, its use in elderly patients requires strict dose individualization and close monitoring. This case demonstrates the clinical risks associated with high-dose therapy in a frail geriatric patient with advanced cardiorenal disease and reinforces the critical role of clinical pharmacy in optimizing medication safety.

References

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  • American Geriatrics Society 2023 Beers Criteria Update Expert Panel. J Am Geriatr Soc. 2023;71(7):2052–2081.
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