MIDWIFERY NOTES

PHARMACOLOGICAL DRUGS USED IN LABOR (PART 1)

Estimated reading: 7 minutes 743 views
By: Sir Bright Boafoh

Introduction to the Topic

Pharmacological drugs used in labor are medications administered to manage pain, assist the labor process, and address potential complications for the mother and fetus. These drugs support the physiological processes of labor, help reduce discomfort, and ensure the health and safety of both mother and baby.

5 Lesson Objectives

  1. Define labor and key associated terms (labor, nausea, anorexia).
  2. Identify the main goals for using pharmacological drugs in labor.
  3. Recognize signs of true labor.
  4. Understand factors to consider when administering pharmacological drugs in labor.
  5. Describe the categories of drugs used in labor and provide examples.

Purpose of Using Pharmacological Drugs in Labor

  1. Provide effective pain relief: Minimize maternal discomfort and pain.
  2. Facilitate labor progress: Help manage complications that may slow or impede labor.
  3. Ensure maternal and fetal well-being: Stabilize maternal and fetal health during labor.
  4. Manage side effects: Control potential symptoms like nausea, vomiting, and anxiety.

Definitions of Key Terms

  1. Labor: The process by which a fetus and placenta are expelled from the uterus. It typically involves contractions of the uterus, dilation of the cervix, and birth of the baby.
  2. Nausea: A sensation of unease and discomfort in the stomach, often preceding vomiting; common during labor and may be exacerbated by certain medications.
  3. Anorexia: A lack of appetite, which can occur during labor as a result of stress, hormonal changes, or medication.

What is a True Labor?

True labor refers to the process of labor that leads to the delivery of the baby. It is characterized by a series of regular, strong uterine contractions that cause progressive changes in the cervix, including dilation (opening) and effacement (thinning).

Characteristics of True Labor

  1. Regular, strong contractions: Increasing in frequency and intensity.
  2. Cervical dilation and effacement: Progressive thinning and opening of the cervix.
  3. Bloody show: A small amount of blood-tinged mucus from the cervix.
  4. Breaking of water: Rupture of the amniotic sac, releasing amniotic fluid.

Example

A laboring patient at Akim Oda District Hospital, Maame Esi, reports intense contractions occurring every five minutes, with visible signs of cervical dilation. The midwife monitors her symptoms to confirm true labor.

What is a False Labor?

False labor refers to contractions that may feel similar to true labor but do not lead to childbirth. These contractions, often called Braxton Hicks contractions, are usually irregular, infrequent, and do not increase in intensity or lead to cervical dilation.

Characteristics of False Labor

  1. Irregular timing and unpredictable pattern
  2. Intensity does not increase over time
  3. Usually felt in the front of the abdomen
  4. May stop with changes in activity or position
  5. No significant cervical changes (dilation or effacement)

Factors to Consider When Using Pharmacological Drugs

  1. Maternal Health: Pre-existing health conditions, allergies, and pregnancy complications.
  2. Fetal Health: Fetal heart rate and overall well-being must be considered before administration.
  3. Labor Stage: Some drugs are safer or more effective at specific stages of labor.
  4. Potential Side Effects: Monitoring for possible adverse reactions in both mother and fetus.

Categories of Drugs Used in Labor

  1. Uterotonics: Drugs that induce or augment labor.
  2. Tocolytics: Drugs that inhibit premature labor.
  3. Analgesics and Anesthetics: Drugs that manage pain.
  4. Antiemetics: Drugs used to manage nausea and vomiting during labor.
  5. Antibiotics: Given to prevent or treat infections that could affect mother or baby.

A. Uterotonics

Uterotonics are medications that stimulate uterine contractions and are used to induce or augment labor. They also help manage postpartum hemorrhage (PPH).

Common uterotonic drugs include:

1. Oxytocin

  1. Purpose: Used to initiate or strengthen labor contractions and reduce bleeding after delivery.
  2. Mechanism of Action: Stimulates the uterine muscles, promoting contractions that facilitate labor.
  3. Administration: Usually administered intravenously for rapid onset.
  4. Side Effects: May cause hyperstimulation of the uterus, fetal distress, or uterine rupture in rare cases.

Image of an Oxytocin

2. Prostaglandins

  1. Example: Dinoprostone and Misoprostol
  2. Purpose: Induce labor by softening the cervix (cervical ripening) and stimulating contractions.
  3. Mechanism of Action: Causes cervical softening and effacement; stimulates uterine contractions.
  4. Administration: Administered as vaginal suppositories, tablets, or gels. Side
  5. Effects: Uterine hyperstimulation, nausea, vomiting, and diarrhea.

Image showing Dinoprostone

Image showing Dinoprostone

Ergometrine and Methylergometrine

  1. Purpose: Primarily used postpartum to control bleeding by enhancing uterine contractions.
  2. Mechanism of Action: Acts on uterine smooth muscle, causing sustained contractions.
  3. Administration: Can be administered orally or intramuscularly. Side
  4. Effects: Hypertension, nausea, and vomiting.

Image if an Ergometrine and Methylergometrine drug

B. Tocolytics

Tocolytics are drugs used to delay preterm labor by inhibiting uterine contractions. They are typically given when premature labor occurs before 37 weeks to allow fetal lung maturation.

Key tocolytics include:

1. Nifedipine

  1. Purpose: A calcium channel blocker used to relax uterine muscles.
  2. Mechanism of Action: Inhibits calcium influx in muscle cells, reducing contractions.
  3. Administration: Usually given orally.
  4. Side Effects: Hypotension, headache, and flushing.

Image of Nifedipine below

2. Magnesium Sulfate

  1. Purpose: Used to protect against preterm labor and provide neuroprotection for the fetus.
  2. Mechanism of Action: Reduces muscle contractions by blocking calcium uptake.
  3. Administration: Administered intravenously.
  4. Side Effects: Flushing, nausea, respiratory depression, and decreased urine output.

Image of a Magnesium Sulfate

3. Terbutaline

  1. Purpose: A beta-agonist used to relax uterine muscles.
  2. Mechanism of Action: Stimulates beta-adrenergic receptors, leading to muscle relaxation.
  3. Administration: Given subcutaneously or orally.
  4. Side Effects: Increased heart rate, anxiety, palpitations, and hyperglycemia.

Image of Terbutaline

C. Analgesics and Anesthetics

Pain management during labor is a critical aspect of maternal care. The choice of analgesic or anesthetic depends on factors like the stage of labor, maternal preference, and the potential impact on the fetus.

1. Epidural and Spinal Analgesia

  1. Purpose: Provides effective pain relief during active labor.
  2. Mechanism of Action: Blocks nerve impulses in the lower spinal region.
  3. Administration: Administered via a catheter in the epidural space of the spine(Epidural). Spinal anesthesia is often used in C-sections.
  4. Side Effects: Hypotension, reduced sensation in the lower body, and headache.

An Image of an Epidural Analgesia

2. Narcotics

  1. Example: Fentanyl, Meperidine and Morphine
  2. Purpose: Short-term pain relief during early labor.
  3. Mechanism of Action: Act on the central nervous system to reduce the perception of pain.
  4. Administration: Given intravenously or intramuscularly.
  5. Side Effects: Nausea, drowsiness, and respiratory depression in both mother and baby.

Images of common Narcotics

3. Nitrous Oxide (Laughing Gas)

  1. Purpose: Provides mild pain relief and relaxation.
  2. Mechanism of Action: Inhaled gas that quickly relieves pain by depressing the central nervous system.
  3. Administration: Inhaled through a mask.
  4. Side Effects: Dizziness, nausea, and disorientation.

An image of Nitrous Oxide (Laughing Gas)

D. Antiemetics

Antiemetics are often given to manage nausea and vomiting that may occur during labor, either due to pain or as a side effect of analgesics.

1. Metoclopramide

  1. Purpose: Relieves nausea and vomiting.
  2. Mechanism of Action: Increases gastric emptying and reduces nausea.
  3. Administration: Given orally or intravenously.
  4. Side Effects: Drowsiness, restlessness, and extrapyramidal symptoms (rare).

An image of a Metoclopramide

2. Ondansetron

  1. Purpose: Also used for nausea relief.
  2. Mechanism of Action: Blocks serotonin receptors involved in the vomiting reflex.
  3. Administration: Usually administered intravenously.
  4. Side Effects: Headache, dizziness, and constipation.

An image of Ondansetron

E. Antibiotics

Antibiotics are used when there’s a risk of infection, such as Group B Streptococcus in the mother, which can be transmitted to the baby during delivery. Administering antibiotics prevents potential neonatal infections.

Summary of Drug Lists for Labor

Analgesics (Pain Relief)

  1. Morphine
  2. Meperidine(Demerol)
  3. Fentanyl

Anesthetics (Pain Blockers)

  1. Epidural anesthesia (Bupivacaine, Ropivacaine)
  2. Spinal anesthesia
  3. Lidocaine (local anesthetic)

Oxytocic Drugs (Labor Induction and Augmentation)

  1. Oxytocin (Pitocin)
  2. Misoprostol (Cytotec)
  3. Dinoprostone (Cervidil, Prepidil)

Tocolytics (Labor Inhibitors)

  1. Magnesium sulfate
  2. Nifedipine (Procardia)
  3. Terbutaline

Anti-emetics (Anti-nausea)

  1. Ondansetron (Zofran)
  2. Metoclopramide (Reglan)
  3. Promethazine (Phenergan)

Antibiotics (Infection Prevention)

  1. Ampicillin
  2. Clindamycin
  3. Cefazolin
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