Skip to content

Tocolytics: Nursing Pharmacology

  • by

What are Tocolytics? Tocolytics are a group of medications that suppress uterine contractions.

Tocolytics are a group of medications that suppress uterine contractions for that reason tocolytics are typically used to prolong pregnancy and delay birth after preterm labor starts before 34 weeks of gestation delaying labor is usually done to transfer the client to a higher health care facility if needed or to administer medications that improve fetal outcomes

Such as corticosteroids which promote fetal lung maturation now the most commonly used tocolytics are magnesium sulfate calcium channel blockers like nephetipine beta2 agonist like terbutaline and nsaids like indomethacin when tocolytics are administered they cause smooth muscle relaxation in the uterus via various mechanisms both magnesium sulfate and calcium

Channel blockers like nephetipine block calcium channels which inhibits the entry of calcium ions into uterine smooth muscles and thus decreases their contractility in addition to its tocolytic effect magnesium sulfate also has a neuroprotective effect on the preterm brain which is more susceptible to injury on the other hand beta-2 agonists bind to the beta-2

Receptors located on the surface of smooth muscle cells ultimately leading to a decrease in the level of intracellular calcium and decreasing their contractility finally nsaids inhibit the enzyme cyclooxygenase which normally helps to produce prostaglandins as a result there’s a decrease in prostaglandin levels which ultimately results in relaxation of the uterine

Smooth muscle now tocolytics can cause several maternal and fetal side effects side effects of magnesium sulfate include nausea flushing and headache in addition magnesium sulfate toxicity can lead to respiratory depression cardiac arrest as well as neurological side effects like altered mental status reduce deep tendon reflexes and muscle weakness now magnesium

Sulfate may have side effects on the fetus as it relaxes the muscles some babies who are exposed to magnesium can present with hypotonia or low muscle tone fortunately the side effect is not permanent and usually improves as magnesium sulfate clears from the baby on the other hand calcium channeled blockers can cause vascular smooth muscle relaxation which may

Result in headache dizziness flushing nausea and hypertension which could decrease blood flow to the fetus the good news is that calcium channel blockers don’t seem to cause side effects on the fetus for beta-2 agonists side effects result from the excessive stimulation of beta-2 receptors elsewhere in the body in the heart beta-2 agonists can cause tachycardia

Arrhythmias and palpitations whereas in vascular smooth muscles they can lead to hypotension other side effects include tremors nervousness hyperglycemia hypokalemia and the development of pulmonary edema in addition beta-2 agonists can cross the placenta to the fetus so another side effect is fetal tachycardia turbutaline should not be administered if the

Client has known cardiac disease or poorly controlled diabetes mellitus finally side effects of nsaids can result from the decreased levels of prostaglandins making the gastric mucosa more susceptible to injury by gastric acid which can lead to gastritis and gastroesophageal reflux now in regard to the fetus nsaids can affect the fetal kidneys and that decreases

The fetal production of urine which is the main component of the amniotic fluid that surrounds and cushions the fetus this ultimately results in oligohydramnios or low amniotic fluid nsaids can also cause a premature closure of the ductus arteriosus which is a small vessel that normally connects the fetal aorta to the pulmonary artery this allows redirection

Of blood coming from the heart away from the non-functioning fetal lungs premature closure of the ductus arteriosus causes the blood to go directly to the fetal lungs overwhelming them and resulting in pulmonary hypertension and heart failure now tocolytics are generally contraindicated if pregnancy continuation poses a risk on the client’s life as in severe

Preeclampsia eclampsia intrauterine infection and active vaginal bleeding tocolytics are also contraindicated before the 20th week and after the 34th week of gestation as well as in clients with premature rupture of the membranes finally fetal contraindications to tocolytics include abnormal fetal heart rate pattern a lethal fetal abnormally like anencephaly or

Intrauterine fetal death in addition there are also specific contraindications for each tocolytic medication for example magnesium sulfate is contraindicated in clients with myasthenia gravis since it can’t aggravate muscle weakness and increase the risk of respiratory muscle paralysis thus leading to respiratory insufficiency magnesium sulfate should also be used

With caution in clients with recent myocardial infarction or those with renal disease as it is excreted by the kidneys on the other hand calcium channel blockers are contraindicated in clients who have hypotension next beta 2 agonist should be avoided in clients who have cardiac disease or uncontrolled diabetes finally nsaids are contraindicated in clients with

Peptic ulcer disease impaired renal function and bleeding disorders nsaids are also contraindicated after 32 weeks of gestation when the risk of premature closure of ductus arteriosus is higher okay prior to administering a tocolytic ensure your client understands the medication is being administered to help delay labor and that there are potential side effects

And that you will be monitoring closely while the client receives the medication then perform a baseline assessment including vital signs spo2s heart and lung sounds uterine activity cervical dilation and effacement and the fetal heart rate or fhr and variability and continue these assessments while your client is receiving the tocolytic lastly be prepared to

Institute intrauterine resuscitation measures to increase fetal oxygenation by administering an iv fluid bolus assisting the client into a lateral position and administering oxygen at eight to ten liters per minute through a non-rebreather face mask now each tocolytic you administer has special nursing considerations before you administer magnesium sulfate obtain

A baseline serum creatinine to determine the client’s renal function and insert an indwelling urinary catheter for accurate measurement of urinary output also assess the client’s deep tendon reflexes or dtrs and be sure to have a vial of the antidote calcium gluconate readily available to use in the event of toxicity because it’s a high alert medication you’ll use

An infusion pump to administer magnesium sulfate intravenously before administration begins ask a second nurse to check the dose and infusion pump settings then start a primary line first with a thousand milliliters of crystalloid fluid and then start a second line for the magnesium sulfate using color-coded tags on the bags and lines of both the magnesium sulfate

And the maintenance fluid to provide another layer of safety you’ll administer a loading dose first so it infuses stay at the bedside and monitor your client closely for adverse reactions then after the loading dose is complete begin infusing the maintenance dose as ordered during administration continue your assessments including any significant changes in the

Client’s baseline that could indicate toxicity or the development of pulmonary edema such as respirations less than 12 breaths per minute or more than 24 breaths per minute so spo2 less than 95 percent shortness of breath or adventitious breast sounds tachycardia or bradycardia absent dtrs decreased level of consciousness urine output less than 30 milliliters

Per hour serum magnesium greater than the therapeutic range of 4 to 8 milligrams per deciliter or the development of either an indeterminate or abnormal fhr if you assess any of these signs or symptoms stop the infusion then administer the calcium gluconate per protocol and notify the obstetrician or midwife immediately all right if your client is prescribed the

Calcium channel blocker nephetipine you will administer the medication orally while your client is receiving the medication continue your assessments and closely monitor for side effects if you notice a decrease in fhr variability or the presence of decelerations this may indicate maternal hypotension if this occurs notify the obstetrician or midwife immediately

And institute appropriate intrauterine resuscitation measures per protocol do not administer nephedipine if your client is hypotensive or hemodynamically unstable the beta 2 agonist terbutaline is most commonly administered subcutaneously and is only used for up to 72 hours due to the risk of significant side effects before administering and after each dose be

Sure to assess the maternal heart rate and the fhr pattern then while the client is receiving terbutaline closely monitor for side effects and assess the client’s vital signs heart and lung sounds blood glucose levels uterine activity and fhr hold the medication and notify the obstetrician or midwife if the fhr is greater than 180 beats per minute or if the fhr

Patterns are indeterminate or abnormal if the maternal heart rate is greater than 120 beats per minute if the client experiences palpitations or if signs of pulmonary edema are present like respirations greater than 30 breaths per minute pulmonary crackles are auscultated or the spo2 is less than 95 percent okay the nsaid indomethacin is administered orally or

Rectally its use as a tocolytic is limited to 48 hours and is not used after 32 weeks of destation due to the risk of fetal side effects involving premature closure of the ductus arteriosus during administration continue your assessments and monitor for side effects all right as a quick recap tocolytics are a group of medications that suppress uterine contractions

They’re used in cases of preterm labor to delay labor to allow time to transfer the client to a higher healthcare facility if needed or to administer medications like corticore steroids that promote fetal lung development the most commonly used tocolytics are magnesium sulfate which is a high risk medication nephetipine which is a calcium channel blocker terbutaline

Which is a beta2 agonist an endomethacin an nsaid side effects can vary among different tocolytic medications side effects of magnesium sulfate include nausea flushing headache and in severe cases neurological side effects for calcium channel blockers common side effects are hypotension headache and dizziness while for beta2 agonists side effects mainly include

Tachycardia arrhythmia and hypotension finally nsaids can increase the client’s risk of gastritis and in the fetus it may result in the premature closure of ductus arteriosus contraindications of tocolytics include gestational age before 20 weeks or after 34 weeks premature rupture of membranes abnormal fhr pattern and client contraindications specific to each

Type of tocolytic there are several important nursing considerations and client education points to consider with tocolytics such as safe administration client and fetal assessment and side effects to report helping current and future clinicians focus learn retain and thrive learn more you

Transcribed from video
Tocolytics: Nursing Pharmacology By Osmosis