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13 - Drugs in obstetrics

Published online by Cambridge University Press:  21 August 2009

Alexander Heazell  and
John Clift
By
Lisa Penny
Alexander Heazell
Affiliation:
University of Manchester
John Clift
Affiliation:
City Hospital, Birmingham
Lisa Penny
Affiliation:
Specialist Registrar in Anaesthetics and Intensive Care, University Hospitals, Birmingham, Queen Elizabeth Hospital, Birmingham, UK
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Summary

Introduction

Drugs used in obstetrics merit special mention because they have their effects on two patients rather than one. Pharmacologically they are of particular interest because they may be transferred across, and metabolised by, another organ, the placenta. It is important for the anaesthetist to have an understanding of the drugs commonly used by obstetricians, the evidence for them and their interface with anaesthetics.

Drugs to increase uterine contractions

Indications

  • Acceleration/augmentation of labour

  • To minimise risk of postpartum haemorrhage (PPH)

  • Treatment of PPH

Oxytocin

  • In the UK a synthetic oxytocin is manufactured under the name syntocinion. It is a nonapeptide used to induce and augment labour and also to minimise blood loss post-delivery.

  • It is thought to act by binding to myometrial cell receptors and increasing smooth muscle contractility.

  • Guidelines from the Royal College of Obstetricians and Gynaecologists recommend that to induce or accelerate labour, oxytocin is given intravenously starting at a rate of 1–2 miU/min, titrated to uterine contractions and increasing every 30 minutes to a maximum of 32 miU/min.

  • It may also be given as a dose of 5 units slowly after delivery of baby during Caesarean section.

  • Can be given as an infusion of 10 U/hr for the treatment prevention of PPH secondary to uterine atony. This is normally for a period of 4 hours.

  • Its main adverse effect is the relaxation of vascular smooth muscle causing hypotension and a reflex tachycardia: this is potentiated in vasoconstricted states such as pre-eclampsia and hypovolaemia. It also has an antidiuretic effect, which can lead to water intoxication in large doses. Other side effects include nausea, vomiting and rashes.

Keywords

antihypertensive agentsatosibanbeta2-adrenergic agonistsnifedipineoxytocinprostaglandinssteroidsobstetricstocolyticsuterine hyperstimulation
Type
Chapter
Information
Obstetrics for Anaesthetists , pp. 140 - 148
Publisher: Cambridge University Press
Print publication year: 2008

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References

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  • Drugs in obstetrics
    • By Lisa Penny, Specialist Registrar in Anaesthetics and Intensive Care, University Hospitals, Birmingham, Queen Elizabeth Hospital, Birmingham, UK
  • Alexander Heazell, University of Manchester, John Clift
  • Book: Obstetrics for Anaesthetists
  • Online publication: 21 August 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511544569.015
Available formats
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Save book to Dropbox

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  • Drugs in obstetrics
    • By Lisa Penny, Specialist Registrar in Anaesthetics and Intensive Care, University Hospitals, Birmingham, Queen Elizabeth Hospital, Birmingham, UK
  • Alexander Heazell, University of Manchester, John Clift
  • Book: Obstetrics for Anaesthetists
  • Online publication: 21 August 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511544569.015
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Drugs in obstetrics
    • By Lisa Penny, Specialist Registrar in Anaesthetics and Intensive Care, University Hospitals, Birmingham, Queen Elizabeth Hospital, Birmingham, UK
  • Alexander Heazell, University of Manchester, John Clift
  • Book: Obstetrics for Anaesthetists
  • Online publication: 21 August 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511544569.015
Available formats
×