Pharmacology of Tocolytic agents Flashcards
What are tocolytic agents?
Drugs designed to inhibit contractions of myometrial smooth muscle cells.
Drugs that decrease uterine contractility
What are the aim of tocolysis?
To stop uterine contractions
To prevent preterm pregnancy
To prevent perinatal morbidity and mortality related to associated with preterm birth.
Commonly used tocolytic medications include?
- β 2 agonists: Terbutaline, retodrine
- calcium channel blockers: Nifedipine, nicardipine
- NSAIDs: Indomethacin, sulindac , ibuprofen, aspirin
- magnesium sulfate.
What is preterm labor?
which refers to when a baby is born too early before 37 weeks of pregnancy
Tocolytics are considered for people with confirmed preterm labor between how many week gestation age?
24 and 34 weeks of gestation age
Tocolytics are considered for people with confirmed preterm labor between how many week gestation age?
24 and 34 weeks of gestation age
and used in conjunction with other therapies that may include corticosteroids administration, fetus neuroprotection, and safe transfer to facilities.
Name Beta 2 agonist that can be used as tocolytic agents?
Terbutaline Isoxsurpin Ritodrine Fenoterol Salbutamol
What is MOA of beta 2 agonist as tocolysis agent?
Is through beta 2 receptor stimulation, causing smooth muscle relaxation.
Why beta 2 agonist should not be used for more than 48 hours? as they can lead to increased risk
as they can lead to increased risk to the mother.
When to use beta 2 agonist?
Used in uncomplicated premature labor between 24th to 33rd weeks of
gestation.
What is FDA recommendation for terbutaline used?
Off label use, FDA has advised that injectable terbutaline should only be used in urgent situations, and that the oral form of the drug should never be used.
Contraindications: of terbutaline?
- Pregnant diabetic or pregnancy induced diabetic patients.
- poorly controlled diabetes mellitus,
- hyperthyroidism,
- Patients taking beta blockers.
Side effects of terbutaline?
Mother: Tachycardia , palpitations, hypotension, dyspnea, chest pain, hypokalemia, hyperglycemia, lipolysis, pulmonary edema, myocardial ischemia.
Fetus: Fetal tachycardia, hyperinsulinemia, hypoglycemia
Contraindications: of Ritodrine.
Poorly controlled thyroid disease, hypertension, and diabetes
Contraindications of foneterol
Diabetes, tachyarrhythmia, hypertrophic obstructive cardiomyopathy, hypersensitivity to fenoterol
Name Ca channel blocker used as tocolytic agent.
Nifedipine and nicardipine
Mechanism of action CCB as tocolytic agent
- Block the influx of calcium ions, thereby reducing the intra cellular calcium, reduces the tone of myometrium and opposes the contraction.
- CCB has prominent smooth muscle relaxant action which is effective if used early enough.
Side effects CCB?
Tachycardia, Flushing , headache, dizziness, nausea, transient
hypotension.
- Administration of calcium channel blockers should be used with care in patients with renal disease and hypotension.
Fetal: Calcium channel blockers have the fewest neonatal adverse effects
- Reduced placental perfusion may cause fetal hypoxia
Why CCB should not be used concomitantly with magnesium sulfate?
use of calcium channel blockers and magnesium sulfate may result in
cardiovascular collapse
Contraindications CCB?
Contraindications: Hypotension, preload dependent cardiac disease.
What is Atosiban?
It is a peptide analogue of oxytocin , acts as an oxytocin receptor antagonist
Effectiveness of Atosiban?
As effective as nifedipine and more effective than beta agonists.
- Fewer side effects than β 2 agonists
Administration of Atosiban?
Atosiban is a modified form of oxytocin that is administered by intravenous infusion for 2 48 hours.
