FRCA Notes


Tocolytics


  • This heterogenous group of drugs are used to arrest or decrease uterine contraction, for example due to:
    • Pre-term labour
    • Uterine hyperstimulation and foetal distress during labour
    • Need for uterine relaxation during LSCS

Pre-term labour

  • Nifedipine is the NICE recommended first-line tocolytic for those in pre-term labour
  • Atosiban, an oxytocin receptor antagonist, is second-line

Foetal distress

  • β2 receptor agonists, e.g. terbutaline IV or salbutamol, are not recommended for tocolysis in pre-term labour, but are the most commonly used in uterine hyperstimulation
    • Up to 10% crosses placenta to cause foetal tachycardia
    • May be more effective than magnesium (Cochrane Library, 1998)

  • GTN
    • Can be used to cause uterine relaxation; it's useful in theatre as it can be rapidly sprayed under the tongue of the awake patient
    • Causes more hypotension than the beta-adrenoreceptor agonists

  • Magnesium is another option