Podcast
Questions and Answers
What is the primary goal of tocolysis in the context of preterm labor?
What is the primary goal of tocolysis in the context of preterm labor?
- To immediately halt labor and expedite delivery.
- To induce labor in cases of post-term pregnancy.
- To delay delivery for a short period (2-7 days) to allow for interventions like administering corticosteroids. (correct)
- To manage pain during labor without affecting its progression.
Which mechanism of action is characteristic of Indomethacin when used as a tocolytic?
Which mechanism of action is characteristic of Indomethacin when used as a tocolytic?
- Non-specific inhibition of both COX-1 and COX-2 enzymes. (correct)
- Selective inhibition of COX-2 enzymes.
- Activation of beta-adrenergic receptors.
- Blocking calcium channels to reduce myometrial contractility.
A contraindication for tocolysis is:
A contraindication for tocolysis is:
- Uterine tachysystole.
- External cephalic version.
- Suspected fetal distress. (correct)
- Preterm labor with intact membranes.
Which tocolytic agent acts by inhibiting the influx of calcium ions into myometrial cells?
Which tocolytic agent acts by inhibiting the influx of calcium ions into myometrial cells?
How does Terbutaline function as a tocolytic?
How does Terbutaline function as a tocolytic?
Which side effect is most closely associated with the use of terbutaline as a tocolytic?
Which side effect is most closely associated with the use of terbutaline as a tocolytic?
What is the mechanism of action of Atosiban?
What is the mechanism of action of Atosiban?
How do nitric oxide donors, such as nitroglycerin, function as tocolytics?
How do nitric oxide donors, such as nitroglycerin, function as tocolytics?
Which of the following describes the primary mechanism of action for magnesium sulfate as a tocolytic agent?
Which of the following describes the primary mechanism of action for magnesium sulfate as a tocolytic agent?
Following administration of magnesium sulfate as a tocolytic, a patient exhibits signs of toxicity. Which of the following is a sign of magnesium sulfate toxicity?
Following administration of magnesium sulfate as a tocolytic, a patient exhibits signs of toxicity. Which of the following is a sign of magnesium sulfate toxicity?
Flashcards
Tocolysis
Tocolysis
Obstetrical procedure using medications (tocolytics) to delay delivery in preterm labor, typically for 2-7 days.
Tocolytics Use
Tocolytics Use
To suppress uterine contractions, delay labor, allow transfer to better facility, or administer fetal lung development meds.
Tocolytics Indications
Tocolytics Indications
Preterm labor, external cephalic version, tachysystole, suspected distress.
Indomethacin MOA
Indomethacin MOA
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Nifedipine MOA
Nifedipine MOA
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Terbutaline MOA
Terbutaline MOA
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Atosiban MOA
Atosiban MOA
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Nitroglycerin MOA
Nitroglycerin MOA
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Magnesium Sulfate MOA
Magnesium Sulfate MOA
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Study Notes
- Pharmacology of Tocolysis focuses on medications that delay delivery in preterm labor.
Tocolysis
- Tocolysis is an obstetrical procedure involving medications (tocolytics).
- It delays delivery in preterm labor for 2-7 days.
- The pharmacologic target is myometrial activity.
- It delays and weakens uterine contractions.
- The goal is to decrease fetal morbidity and mortality.
- Medications used are off-label as there are no USFDA-approved medications.
Tocolytics
- Tocolytics suppress uterine contractions.
- Tocolytics are used in cases of preterm labor to delay labor.
- They facilitate the transfer of a client to a higher health care facility, if needed.
- They administer medications, like corticosteroids, that promote fetal lung development.
- Examples of tocolytics: Magnesium Sulfate, Terbutaline (B2-agonist), Indomethacin (NSAID), and Nifedipine (calcium channel blocker).
- Terbutaline has an increased risk as a medication.
Indications for Tocolysis
- Preterm labor with contractions.
- External cephalic version.
- Uterine tachysystole.
- Suspected fetal distress.
Contraindications for Tocolysis
- Intrauterine fetal demise.
- Non-reassuring fetal status.
- Severe preeclampsia, eclampsia.
- Maternal hemorrhage.
- Premature rupture of membranes.
Cyclooxygenase Inhibitors (Indomethacin)
- Mechanism: Nonspecific inhibition of COX-1 and COX-2 enzymes, decreasing prostaglandin production.
- Side effects: gastritis, nausea, oligohydramnios, and premature PDA closure.
Calcium Channel Blocker (Nifedipine)
- Mechanism: Calcium channel blockade and inhibition of calcium ions influx into the cell, and inhibition of release of intracellular calcium from the sarcoplasmic reticulum.
- Side effects: dizziness, headache, and palpitations.
Beta Agonists (Terbutaline)
- Mechanism: Binding of beta-2 adrenergic receptors.
- Stimulates adenyl cyclase.
- Increases formation of intracellular cAMP.
- Inhibition of MLCK.
- Side effects: vasodilation, hypotension, tachycardia, palpitations, tremor, shortness of breath, pulmonary edema, and fetal tachycardia.
Oxytocin Receptor Antagonists (Atosiban)
- Mechanism: Competitive inhibition of oxytocin binding to oxytocin receptors, preventing IP3 formation and calcium release from SR.
- Side effects: Hypersensitivity reactions and injection site reactions.
Nitric Oxide Donors (Nitroglycerin)
- Mechanism: Nitric oxide synthesized from L-arginine; catalyzed by nitric oxide synthase (NOS).
- NO activates guanyl cyclase, which increases cGMP formation.
- Activates myosin light chain phosphatase, leading to smooth muscle relaxation.
- Side effects: HOTN, headache, flushing, and palpitations.
Magnesium Sulfate
- Mechanism of action: May compete with calcium at membrane voltage-gated channels, decreasing calcium release from SR.
- Can cause membrane hyperpolarization.
- Also contributes to inhibition of MLCK.
- Reduces myometrial contractility.
- Immediate onset; effective for 30 minutes (continuous infusion).
- Side effects: flushing, headache, and diaphoresis.
- Toxicity: respiratory depression, pulmonary edema, and arrest.
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