Furosemide by continuous subcutaneous infusion

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Note: Administration via the subcutaneous (SC) route is off label

Management of symptomatic fluid overload in patients with chronic heart failure or end-stage renal failure (ESRF) who require parenteral diuretics as a result of:

• having minimal or no response to high-dose oral diuretics, or
• no longer being able to swallow oral diuretics, and
• having no possible or appropriate venous access.

There are no absolute contraindications to the use of furosemide in palliative care. However, the prescriber must carefully consider the following conditions before prescribing furosemide and the dose should be carefully titrated:

• anuria
• renal failure because of nephrotoxic or hepatotoxic drugs
• hepatic encephalopathy
• severe hypokalaemia or severe hyponatraemia, and
• dehydration or hypovolaemia.

Patients allergic to sulphonamides may show cross-sensitivity to furosemide.

Furosemide should be used with caution in patients :

• with severe electrolyte disturbances
• who are elderly (lower dose)
• with renal and hepatic impairment 
• with diabetes mellitus (may cause hyperglycaemia), or
• who have partial obstruction of urinary outflow, for example, prostatic hypertrophy.

Drug interactions

For the full list see the manufacturer’s summary of product characteristics (SPC) or refer to the current edition of the BNF (British National Formulary (NICE))

• Concurrent use of furosemide with risperidone in elderly patients with dementia is associated with increased risk of death.
• Furosemide-induced electrolyte disturbances can increase the risk of:
  • cardiac arrhythmia and death with drugs known to prolong the QT interval, such as citalopram or methadone, and
  • digoxin toxicity.
• Furosemide can decrease vancomycin levels by up to 50 %.
• Furosemide can affect glucose tolerance, necessitating increases in the dose of insulin required.

Liver impairment: use with caution.

Renal impairment: monitor during use.

Monitoring

All patients require close monitoring.

For patients in the last days of life

• Blood tests are not routinely required in the last days of life.
• Monitor clinical symptoms and signs of breathlessness, oedema, etc as normal.
• Consider whether monitoring weight is appropriate.
• Adjust the dosage accordingly.
• Monitor the injection site for signs of irritation or infection.
• Consider blood glucose monitoring.

For patients with a longer prognosis, not considered to be in the last days of life

It is important that patients are reviewed every 24 hours, aiming for a daily weight loss of no more than 1 kg/day.

Blood monitoring should be carried out on a regular basis to monitor for renal dysfunction, unless the monitoring of blood chemistry would not change management plans.

• Monitor the injection site for signs of irritation or infection.
• Consider blood glucose monitoring.

Side effects

For the full list see the manufacturer’s Summary of Product Characteristics (SPC) or refer to the current edition of the BNF (British National Formulary)

• Transient pain at the site of subcutaneous injection.
• Mild gastrointestinal disturbances.
• Biochemical disturbances.
• Tinnitus and deafness.

CSCI 

Use the previous oral (PO) 24-hour requirement as a starting dose for CSCI via a syringe pump. Titrate up or down according to response.

A PO:intravenous (IV):SC conversion ratio of 1:1:1 is generally used (based on bioavailability.

Infuse subcutaneously over 24 hours.

As furosemide injection is 10 mg/mL, the practical dose limit for a syringe pump is 200 mg/24 hours for a 30 mL syringe.

Higher doses may need two syringe pumps or consideration of use of a 50 mL syringe (dependent on lock box availability and risk assessment) to accommodate the increased infusion volume.

Diluent: If remaining syringe volume allows for diluent, dilute with 0.9% saline for injection. However, a diluent may not be necessary.

Do not mix or dilute with glucose solutions.

Compatibility: Do not mix with any other drugs. Furosemide injection is alkaline and there is a high risk of incompatibility when mixed with acidic drugs.

Subcutaneous bolus 20 mg (2 mL) subcutaneously as required.

The concentration of available formulations makes doses greater than 20 mg (2 mL) at a single injection site impractical. If a 40 mg injection is needed, the dose can be split into 2 x 20 mg (2 mL) injections, given at separate sites.

Diuresis will be stimulated within 30 minutes and last for approximately 4 hours.

Consider ‘rescue’ bolus doses of subcutaneous furosemide in cases of more acute decompensation or where pulmonary oedema is suspected.

Discontinuing treatment: seek specialist advice

This may be needed if:

• treatment is effective and oral route is recovered
• treatment is ineffective
• the patient is experiencing side effects, or
• the patient is in the last days of life and it is no longer felt to be necessary or appropriate.

• Recommended infusion sites are the upper chest and upper anterior of the arms. Infusion sites are restricted in patients with heart failure due to probable oedema.
• Syringe pump site reactions may occur; most are mild, but occasionally can be more troublesome. The cannula should be resited at the first sign or symptom of a site reaction (redness, swelling, pain).
• Oral bumetanide 1 mg is equivalent to oral furosemide 40 mg.
• Exposure to light may cause degradation and discolouration. Do not administer if the solution is discoloured.
• Do not start a patient on SC furosemide without regular assessment.
• Inform the patient and carers that treatment will provide symptomatic relief only.

Furosemide 10mg/mL Injection BP (Hameln). Summary of Product Characteristics (SPC). Accessed 03 Feb 2025 https://www.medicines.org.uk/emc/ 

Furosemide monograph. Palliative Care Formulary Accessed 03 Feb 2025. https://www.medicinescomplete.com/#/ 

Furosemide monograph. The Syringe Driver. Continuous Subcutaneous Infusions in Palliative Care. Andrew Dickman and Jennifer Schneider. 4th edition. 2016. OUP 

Zacharias, H., et al. (2011). "Is there a role for subcutaneous furosemide in the community and hospice management of end-stage heart failure?" Palliative Medicine 25(6): 658-663