Uterine Drugs Flashcards
Oxytocin description
Peptide hormone secreted by the posterior pituitary -> milk ejection
Uterus becomes more sensitive to oxytocin during second half of pregnancy
Oxytocin mechanism
Activates Gq->Increase calcium -> MLCK -> contraction increases PG synthesis which further stimulates contraction of uterus
Oxytocin Indication
**DOC for induction of labor** Augment dysfunctional labor **Limit post partum hemorrhage** Challenge test -> fetal hypoxia -> measure heart rate Induce abortion
Oxytocin Adverse
Rare: fetal distress, placental abruption, uterine rupture
Activate vasopressin receptors -> fluid retention, hyponatremia, seizures and death
Hypotension when given as a bolus
Uterine stimulants
Oxytocin Eronovine Methylergonovine Carboprost Tromethamine Dinoprostone Misoprostol
Ergonovine and Methylergonovine description
Partial alpha agonist and some 5-HT
Sensitivity to ergo alkaloids increases dramatically during pregnancy
Ergonovine and Methylergonovine indication
Second line for post partum hemorrahge when oxytocin is ineffective (or use both)
Found in breast milk
Ergonovine and Methylergonovine Adverse
HTN, HA, seizure, nausea, vomiting, chest pain, leg cramps
*Gangrene in nursing infant
Ergonovine and Methylergonovine contraindications
Angina MI Pregnancy CVA HTN
Carboprost and Tromethamine description
PGF2 alpha analog
Carboprost and Tromethamine indication
Induce abortion in second trimester
Post - partum hemorrhage (3rd line of treatment)
Carboprost and Tromethamine PK
IM
Ergonovine and Methylergonovine PK
IM
Found in breast milk
Oxytocin PK
IV (slow)
IM
Nasal spray
Dinoprostone description
PGE2
Dinoprostone indication
Induce abortion in second trimester
Evacuate uterus after missed abortion
Benign hydatiform mole
Ripen the cervix
Dinoprostone PK
Vaginal insert or suppository
Cervical gel
Misoprostol description
PGE1 analog
*Not FDA approved for OB use (only approved for use with NSAID induced gastric ulcers)
Misoprostol indication
Ripen cervix
Induce labor
Post-partum hemorrhage
Tocolytics (uterine relaxants)
Magnesium sulfate Indometahcin Nifedipine Atosiban Terbutaline (beta 2 agonist)
Magnesium sulfate
Similar efficacy to terbutaline with better tolerance
Uncouples excitation contraction in myometrium (opposes calcium)**
Magnesium sulfate indication
Most popular tocolytic
Magnesium sulfate PK
crosses the placenta
Magnesium sulfate adverse
Respiratory depression
Cardiac arrest
Indomethacin description
NSAID
Indomethacin Mechanism
Inhibit PG synthesis (which stimulates uterine contraction)
Indomethacin indication
Delay preterm labor
Indomethacin PK
Crosses placenta
Indomethacin adverse
Oligohydramnios due to a decreas in fetal renal blood flow (48h)
Premature closure of ductus arteriousus
Indomethacin contraindications
Not recommended after 32 weeks because AE are more common
Nifedipine description
Calcium channel blocker
Effective and safe
Nifedipine mechanism
Inhibits contractility
Decreases calcium -> decreases MLCK
Nifedipine indication
more successful prolongation of preterm pregnancy
Nifedipine adverse
Maternal tachycardia
palpitations
flushing, nausea
HA and dizziness
Atosiban description
Competitive oxytocin receptor antagonist; not available in the U.S.
Terbutaline (beta two agonist) description
Activates Gs->increases cAMP -> increases PKA -> phosphorylates SM-MLCK -> SM-MLCK has decreased affinity for calcium-calmodulin complex -> myosin is not phosphorylated -> smooth muscle relaxation
Phased out and replaced by magnesium sulfate due to AE
Terbutaline (beta two agonist) indication
Injectable terbutaline needs to be limited to 72 hrs or less
Oral terbutaline should not be used to treat preterm labor
Terbutaline (beta two agonist) adverse
Palpitation, tremor Nausea, vomiting Anxiety Chest pain and dyspnea Hyperglycemia Hypokalemia Hypotension
Pulmonary edema
Cardiac insufficiency
Arrhythmia, MI
Maternal death
Terbutaline contraindication
Got a black box warning in 2011
