Term
| Which peptide is responsible for milk let down? |
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Definition
| Oxytocin a Gq coupled hormone that is also responsible for uterine contractions to maintain labor. It also stimulates PG synthesis thus further stimulates contractions. NB that only during the second half of pregnancy do the oxytocin Rs get upregulated. |
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Term
| What is the DOC for postpartum hemorrhage? |
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Definition
| Oxytocin, if ineffective then give ergonovine or methylergonovine IM |
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Term
| What is the oxytocin challenge test? |
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Definition
| It is a test to check the placental circulatory reserve after IV infusion. Fetal heart rate is monitored as an indirect indicator of fetal hypoxia in which case may warrent immediate caesarean delivery |
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Term
| Can oxytocin be used for abortions? |
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Definition
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Term
| The routes of oxytocin delivery differ for each use, list them and match them up accordingly? |
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Definition
IV – labor indcution
IM – control postpartum bleeding
Nasal spray – promote milk ejection
NB that its eliminated by kidneys and liver and has a T1/2 of 5 mins |
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Term
| What are some of the A/Es of oxytocin? |
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Definition
| Activation of vasopressin receptors: water intoxication -> hyponatremia -> heart failure, seizures, death ; if given too early will result in: fetal distress, placental abruption, uterine rupture; bolus injections -> hypotension thus diluted IV given instead |
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Term
| What are some contradictions for oxytocin use? |
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Definition
| Fetal distress, prematurity, abnormal fetal presentation, cephalopelvic disproportion, predispositions for uterine rupture |
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Term
| What adrenergic receptor is dramatically increased with pregnancy? |
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Definition
| Alpha Rs, thus ergot alkaloids like (?) Ergonovine & methylergonovine which are partial alpha R & serotonin (some) R agonist have increased activity. NB that ergots at small doses will evoke rhythmic contraction & relaxation of the uterus but at higher conc. will induce a powerful and prolonged contraction. |
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Term
| Ergots at doses used for postpartum hemorrhage give minimal A/Es, but some include? |
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Definition
| Hypertension, headache, possible seizures; nausea, vomiting, chest pains, dyspnea, leg cramps have also be reported. |
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Term
| What are the contradictions for using these ergots? |
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Definition
| Angina pectoris, MI, pregnancy, strokes, TIAs, hypertension |
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Term
| Why might nursing infants develop gangrene? |
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Definition
| Cause ergots are found in breast milk thus prolonged use can lead to ergot poisoning (ergotism) |
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Term
| What are more effective stimulants of uterine contractions than oxytocin at the second trimester? |
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Definition
| Prostaglandins. Dinoprostone (PGE2) & Carboprost tromethamine (PGF2-alpha). NB that their synthesis is inhibited by NSAIDs (aspirin & ibuprofen) thus increasing the length of gestation, spontaneous labor or even interrupt premature labor |
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Term
| What is the third line Rx for postpartum hemorrhage? |
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Definition
| If it’s due to uterine atony and doesn’t respond to either oxytocin or ergonovine then Carboprost Tromethamine shud be given IM. NB it can also be used to induce abortion in 2nd trimester |
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Term
| What role does dinoprostone play? |
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Definition
| It has abt four roles: inducing abortion in second trimester; evacutation of the uterine contents in missed abortions; management of benign hydatidiform mole; ripening of the cervix for induction of labor. Is usually given as a vaginal insert/ suppository or cervical gel |
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Term
| What Rx do u know that is a PGE1 analogue? |
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Definition
| Misoprostol, it causes cervical ripening -> labour, used for postpartum hemorrhage. NB that these uses are not FDA approved, what is approved is for reducing the risk of NSAID-induced gastric ulcers |
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Term
| What is the one uterine relaxant u know and when is it used? |
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Definition
| Tocolytics, used to allow Tx w/ corticosteroids for fetal lung surfactant production and also to allow intrauterine fetal resuscitation |
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Term
| What are some A/Es of using tocolytics? |
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Definition
| Since they are very potent, must be used with great care else will cause: pulmonary edema, MI, respiratory/ cardiac arrest, death; newborns of mothers given this drug develop: respiratory depression, intraventricular hemorrhage & necrotizing enterocolitis |
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Term
| What are the absolute contraindication for tocolytics? |
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Definition
| Acute fetal distress (except for intrauterine resuscitation), chorioamnionitis, eclampsia or severe preeclampsia, fetal demise (of a singleton pregnancy), fetal maturity & maternal hemodynamic instability |
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Term
| What is the most commonly used tocolytic agent? |
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Definition
| Beta-2 agonists, a more relavtively specific Beta-2 agonist is Terbutaline (used for premature labor but not FDA-approved) |
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Term
| Are Beta-2 agonists effective in treating preterm labor? |
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Definition
| No so much but they can arrest it for atleast 48-72 hrs |
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Term
| How doe Beta-2 agonists in the myometrium work? |
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Definition
| We know its Gs couple this PKA phosphorylates SmMLCK making it have a lower affinity for Ca2+-calmodulin complex, thus SmMLCK cannot phosphorylate myosin -> myometrial SM relaxes |
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Term
| What are the A/Es of Beta-2 agonists? |
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Definition
| There are many and its F***ED up!!! |
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Term
| Which tocolytic is initially given in a hospital setting but later can be given as outpatient? |
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Definition
| Terbutaline, it is given in the hospital first to manage any obstetric complications; it works by decreasing frequency, intensity and duration of uterine contractions, it works best btw 20-33 wks of gestation or in whom labor is not far advanced and there is no indication of ruptured fetal membrane. NB that it can be given orally, or parentally |
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Term
| What uterine relaxant would u give a pt that is diabetic, hypertensive or has heart dz or has hyperthyroidism? |
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Definition
Magnesium sulphate, it uncouples excitation-contraction in myometrial cells through inhibiton of cellular action potentials. Magnesium toxicity can be life threatening (recall it’s a Ca2+ antagonist):
8-10mM – lose patellar reflex
10-12mM – respiratory depression
12-15mM – respiratory paralysis
>15mM – cardiac arrest |
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Term
| What is the main NSAID used to delay premature labor? |
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Definition
| Indomethacin, given orally or rectally for 24 to 48 hrs; may close fetal ductus arteriosus, esp after 32 wks when its more sensitive |
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Term
| What (voltage-dependent) Ca2+ channel blocker is a tocolytic agent? |
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Definition
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Term
| Which competitive antagonist to oxytocin Rs is not available in USA? |
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Definition
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