Do We Administer Too Much Oxytocin?

Pitocin is the drug we love and hate.  If a laboring patient on pitocin for a long time end up in cesarean section, you often find that pitocin infusion after the baby is born is less effective in giving you the firm uterine tone. Your surgeon may ask you to give more pitocin in the hope of improving the uterine tone. Rarely, giving more pitocin would help in that scenario. Have you ever wondered why? Here below are some quick facts that will help you understand why pitocin would be less effective.

Receptor physiology/MOA

  • Receptor modulation is time-dependent (not dose-dependent)
  • Phaneuf (J Reprod Fert 2000)
    • 60- to 300-fold decrease mRNA expression due to receptor desensitization when exposed to prolonged pitocin infusion.
  • Robinson (2003)
    • Loss of Ca2+ flux after 6 hours (50% at 4.2hr)
    • Receptors remained responsive to PGF2

Now you see why less is more. In addition, with quick infusion of pitocin, it may cause HOTN, flushing, headache, nausea etc.

There are a few RTC studies which have demonstrated the effectiveness of rule of threes. If pitocin of IV push 3units is ineffective, then you can repeat 2 more times. If the uterine tone is still inadequate, time to switch to other medications to modulate different receptors on the myometrium.

  • Rule of Threes (Tsen, 2010 and 2015)
    • Based on extensive reviews and RCT conducted in 2015
  • step-wise algorithm
  • 3IU over 15s; repeat q3min PRN tone (total 3 doses)
  • 3IU/hr infusion (50ml/hr)
  • if inadequate tone, Δ to 3 pharmacologic alternatives
  • RCT study (Anesthesiology 2015): A “rule of threes” algorithm using oxytocin 3 IU results in lower oxytocin doses when compared with continuous-infusion oxytocin in women undergoing elective cesarean delivery.

Sometimes, LESS is MORE.

 

5 Comments Add yours

  1. Chardin says:

    I suspect the person asking for more Pitocin is the gyn? (Mine don’t btw…if there is a problem with uterine tone after a reasonable dose of pit, its methergine or hemabate)

    I don’t think “we” are giving too much. Your gyn is. but then, since when did we start looking to them for expertise in pharmacology? So, alternately, when the gyn asks for 400 mcgs of iv nitroglycerine to relax the uterus during, say, a twin delivery, we giggle and say “I think I’ll start with 10 and we’ll go from there”.

    Liked by 1 person

    1. Behind The Drape says:

      Thanks for your comments. I agree that most of us don’t like to give too much pitocin. However, there are some very seasoned OB providers who still do give lots of pitocin. I have seen that myself. I was hoping this post will raise some awareness of the usage of the pitocin.

      Like

  2. Chuck says:

    A mi también siempre me gustaron, aunque el falso color que usaron para pintarlas no quedó bien para mi; lo único bueno es que repararon las partes rotas de esas y otras estatuas de la ciudad. Y gracias por los conmitareos!! Espero que sigas leyendo las entradas y con ese interés por la ciudad.

    Like

  3. Gertie says:

    c’est long et c’est …La censure du texte de loi est à l’initiative du Conseil Cotnsituniotnel, aucunement de l’UMP, du gouvernement ou de Nicolas Sarkozy. Vous auriez pu nous épargner ce pensum. Etonnez-vous, après que je ne valide pas vos commentaires quand de surcroît vous les agrémentez de prises à partie personnelles.

    Like

  4. Sure wish I could be there to see you finish the race…..no doubt about it!Keep paddling Cap’n it’s just around the bend and watch out for those Asian carp!!!-Bryan B.

    Like

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