What is the half-life of Atosiban (oxytocin/vasopressin receptor antagonist)?

Half-Life of Atosiban and Its Clinical Clearance

The half-life of atosiban is biphasic with an initial half-life of 13 ± 3 minutes and a terminal half-life of 102 ± 18 minutes, with an effective half-life of 18 ± 3 minutes. 1

Pharmacokinetic Profile

• Atosiban is an oxytocin/vasopressin receptor antagonist with a relatively rapid clearance from the body 1
• After intravenous infusion, plasma concentrations of atosiban decline rapidly in a biexponential manner 1
• Steady-state plasma concentrations (approximately 442 ± 73 ng/ml) are achieved within 1 hour of starting intravenous infusion 1
• The plasma clearance of atosiban is relatively high at 42 L/hr 1
• The volume of distribution is approximately 18 L, consistent with distribution into extracellular fluid 1

Clinical Implications

• The short effective half-life of atosiban (18 minutes) means that drug effects diminish rapidly after discontinuation of infusion 1
• This pharmacokinetic profile allows for precise control of drug effect during clinical use for tocolysis in preterm labor 1, 2
• When used for maintenance therapy after acute tocolysis, atosiban is typically administered as a continuous subcutaneous infusion (30 μg/min) to maintain therapeutic levels 3
• The rapid clearance makes atosiban suitable for situations requiring quick reversal of effect, such as when delivery becomes necessary despite previous tocolytic treatment 1, 2

Comparison with Other Medications

• Atosiban's half-life is considerably shorter than many other medications:
  • Much shorter than etoricoxib (20 hours) 4
  • Shorter than tolvaptan (12 hours) 5
  • Shorter than rivaroxaban (7-11 hours) 6
  • Shorter than apixaban (8-14 hours) 6
  • More comparable to short-acting NSAIDs like ibuprofen (2-6 hours) 7

Clinical Applications

• The short half-life of atosiban makes it particularly suitable for acute management of preterm labor, with rapid onset and offset of action 1, 2
• In fertility treatments, atosiban has been used to reduce uterine contractility during embryo transfer, with the short half-life allowing precise timing of the effect 8
• The rapid clearance means that drug effects will be substantially diminished within 1-2 hours after stopping infusion, with near-complete elimination after 4-5 half-lives (approximately 1.5 hours based on effective half-life) 1

The pharmacokinetic profile of atosiban in pregnant patients appears similar to that in non-pregnant women, suggesting consistent drug behavior across these populations 1.