What are the differences between terlipressin and noradrenaline (norepinephrine) in terms of mechanism of action, duration of action, and clinical uses, particularly in adults with cirrhosis and hepatorenal syndrome?

Key Differences Between Terlipressin and Noradrenaline

Both terlipressin and noradrenaline are effective vasoconstrictors for hepatorenal syndrome, but terlipressin is the preferred first-line agent based on more robust evidence, superior efficacy in acute-on-chronic liver failure, and the practical advantage of peripheral IV administration without requiring ICU monitoring in most patients. 1, 2

Mechanism of Action

Terlipressin is a vasopressin analog that acts as a V1 receptor agonist, causing vasoconstriction primarily in the splanchnic circulation, which reverses the splanchnic vasodilation responsible for HRS. 3 This mechanism directly addresses the pathophysiology of HRS by restoring effective arterial blood volume. 3

Noradrenaline is an α-1 adrenergic receptor agonist that acts directly on vascular smooth muscle cells to cause systemic vasoconstriction and increase mean arterial pressure. 1 While effective, it does not specifically target splanchnic vasodilation as selectively as terlipressin. 1

Duration of Action and Administration

Terlipressin has a longer duration of action, allowing for:

• Intermittent bolus dosing every 4-6 hours (1-2 mg per dose) 1, 4
• Continuous infusion starting at 2 mg/day with equal efficacy but lower total daily doses and fewer side effects 1, 4
• Peripheral IV line administration without requiring central venous access 4, 5
• Ward-level monitoring in patients with ACLF grade <3, avoiding routine ICU admission 4, 5

Noradrenaline has a shorter half-life, requiring:

• Continuous IV infusion at 0.5-3 mg/h (or 5-10 μg/min) 1, 2
• Mandatory central venous line placement 2
• ICU-level monitoring in most countries due to infusion requirements 2

Clinical Efficacy

In standard HRS-AKI, both agents show comparable efficacy:

• Noradrenaline achieves HRS reversal in 39-70% of patients 1
• Terlipressin achieves HRS reversal in 36-44% of patients 1
• Small randomized trials (totaling 195 patients) showed no significant difference in response rates or survival 1, 6

In acute-on-chronic liver failure (ACLF), terlipressin demonstrates clear superiority:

• Day 4 response: 26.1% with terlipressin vs 11.7% with noradrenaline (p=0.03) 7
• Day 7 response: 41.7% with terlipressin vs 20% with noradrenaline (p=0.01) 7
• HRS reversal: 40% with terlipressin vs 16.7% with noradrenaline (p=0.004) 7
• 28-day survival: 48.3% with terlipressin vs 20% with noradrenaline (p=0.001) 7
• Reduced need for renal replacement therapy: 56.6% with terlipressin vs 80% with noradrenaline (p=0.006) 7

Safety Profile

Terlipressin carries a higher risk of:

• Ischemic complications in 12% of patients (arrhythmia, angina, digital/splanchnic ischemia) 1
• Respiratory failure in 30% of patients, particularly those with ACLF grade 3 or baseline hypoxemia 1
• Treatment-limiting adverse events in 23.3% of patients 7
• All ischemic complications are reversible upon discontinuation 7

Noradrenaline has:

• Lower rate of treatment-limiting adverse events (8.3%) 7
• Fewer ischemic complications overall 7
• Risk of variceal bleeding (9.5% vs 0% with terlipressin in septic shock) 8

Clinical Uses Beyond HRS

Terlipressin has additional indications:

• Variceal bleeding control by reducing portal pressure 3
• Norepinephrine-resistant septic shock in cirrhosis (92.9% achieved MAP >65 mmHg vs 69.1% with noradrenaline, p=0.005) 8
• Prevention of variceal bleeding during septic shock 8

Noradrenaline is primarily used for:

• Septic shock as first-line vasopressor in non-cirrhotic patients
• Alternative to terlipressin when terlipressin is contraindicated or unavailable 1, 2

Practical Considerations for Drug Selection

Choose terlipressin when:

• Patient has ACLF (any grade) with HRS-AKI 7
• Ward-level care is preferred to avoid ICU transfer 4, 5
• Central line placement is contraindicated or unavailable 4, 5
• Concurrent variceal bleeding risk exists 8
• Contraindications are absent: SpO2 <90%, active ischemia, serum creatinine >5 mg/dL 4, 5

Choose noradrenaline when:

• Terlipressin causes ischemic complications requiring discontinuation 1
• Terlipressin is unavailable or unaffordable 2
• Patient already requires ICU care with central access 2
• Patient has standard HRS without ACLF (comparable efficacy) 6

Mandatory Albumin Co-Administration

Both agents require concurrent albumin to optimize circulatory function and treatment efficacy:

• Day 1: 1 g/kg IV (maximum 100 g) 1, 4, 2
• Subsequent days: 20-40 g/day until treatment completion 1, 4, 2
• Terlipressin alone without albumin has only 25% response rate vs 77% with combination 4

Cost Considerations

Terlipressin is significantly more expensive:

• Average cost: USD $750 per treatment course 9

Noradrenaline is substantially cheaper:

• Average cost: USD $350 per treatment course 9
• However, ICU costs may offset drug savings 2

Predictors of Response (Applicable to Both)

• Baseline bilirubin <10 mg/dL 1, 4
• Baseline serum creatinine <5 mg/dL 1, 4
• MAP increase ≥5-10 mmHg by day 3 1, 4
• Lower ACLF grade 7

Common Pitfalls to Avoid

• Never use terlipressin without albumin - efficacy drops dramatically 4
• Do not continue terlipressin if ischemic symptoms develop, even if symptoms resolve - permanent discontinuation is required 1
• Screen for hypoxemia before starting terlipressin - SpO2 <90% is an absolute contraindication 4, 5
• Do not assume noradrenaline is safer in ACLF - despite fewer ischemic events, it has worse mortality outcomes 7
• Assess ACLF grade before drug selection - terlipressin superiority is most pronounced in ACLF 7