Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

RGU Exam 2 > Pharmacology of Obstetrics > Flashcards

Pharmacology of Obstetrics Flashcards

1
Q

Utertonic Agents Function

A
  • Promotes contractions of uterine smooth muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Tocolytic Agents Function

A
  • Suppresses contractions of uterine smooth muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Clinical reasons to soften cervix and enhance uterine contraction

A
  • Induction of labor (before spontaneous contractions)

*limit an extended pregnancy

*membrane rupture w/o labor

*gestational hypertension or diabetes

*prevent early rupture of membrane

*aid in placental insufficiency

  • Augmentation of labor
  • Therapeutic abortion (or post-spontaneous abortion)
  • Post-partum hemorrhage (PPH) control- the leading cause of maternal mortality worldwide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Clinical reasons to suppress uterine contractions

A
  • Prevent/delay premature labor to buy time to:

*give antenatal corticosteroids time to work to get fetal lungs producing surfactant

*get mo to a facility w/ proper lvl NICU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Major Categories of Uterotonic Agents

A
  • Some classes of prostaglandins

*PGE (1 and 2)

*PGF2alpha

*used for cervical ripening and induction

  • Oxytocin

*used for induction/augmentation; OT for PPH

  • Progesterone receptor antagonist

*same use as oxytocin

  • Ergots

*used for PPH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Major Categories of Tocolytic Agents

A
  • Progesterone (preventative)
  • MgSO4
  • Ca2+ channel blockers
  • Oxytocin antagonists
  • Beta-adrenergic agonists
  • Prostaglandin synthesis (cyclooxygenase) inhibitors
  • Nitric oxide donors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ca2+ effect on Uterine contraction

A
  • Increasing Ca2+ promotes contraction
  • Decreasing Ca2+ prevents contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

General mechanism in myometrial cell leading to contraction

A
  • Action potential depolarize myometrial cell membrane
  • Opening of voltage-gated Ca2+ channels; entry of Ca2+
  • Ca2+ binds calmodulin
  • Activates myosin light-chain kinase (MLCK)
  • Enables interaction of myosin w/ actin needed for contraction
  • MLCP activation—>relaxation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Uterotonic Agents Maternal Contraindications

A
  • Unfavorable prior uterine incision type
  • Contracted or distorted pelvic anatomy
  • Abnormally implanted placentas
  • Active infection or cervical cancer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Uterotonic Agents Fetal Contraindications

A
  • Substantial macrosomia
  • Severe hydrocephalus
  • Malpresentation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Adverse effects from prolonged stimulation of uterine contraction

A
  • Persistent uteroplacental insufficiency
  • Sinus bradycardia
  • Arrhythmias
  • Fetal death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Prostaglandins

A
  • Cyclic fatty acid compounds derived from arachidonic acid
  • Endogenous PGs are produced by placenta and fetus
  • Decreased by progesterone
  • Increased by estrogen
  • Inhibitory prostaglandins (prostacyclins) also expressed throughout pregnancy which may play a role in quiescence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Clinical use of prostaglandins in pregnancy

A
  • Increase uterine smooth muscle contractility
  • Aid in cervical ripening

*increases efficacy of induction

*safest in women w/ unscarred uterus

  • More effective than oxytocin in stimulating uterine contraction thru second trimester
  • Abortifacient weeks 12-20
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Prostaglandins MOA for cervical ripening

A

In cervix, PG causes:

  • Dissolution of collagen bundles
  • Increases the submucosal water content
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Prostaglandin MOA for uterine contraction

A
  1. Inc. IP3-mediated Ca2+ release from SR
  2. Inc. freq. of APs, thus inc. Ca2+ entry thru VGCCs
  3. Activate non-specific cation channels (inc. Ca2+)
  4. PGEs activate MLCK and inactivate MLCP by blocking adenylyl cyclase (cAMP, PKA)

5, PGF2alpha may also inc. Ca2+ sensitivity of apparatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Dinoprostone

A
  • Naturally occuring PGE2
  • Approved for single-dose cervical ripening
  • Clinical trials show it may be less effetive than other PGs
  • Available forms: gel, time-release vaginal insert, and 10mg suppository
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Misoprostrol

A
  • PGE1 analogue
  • Cheaper than dinoprostone and has shorter half-life (so easier to manage)
  • Can be vaginal or oral
  • Higher rates of uterine contraction abnormality, but otherwise similar safety profile to dinoprostone
  • Effective for ripening and induction, though off-label use
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Carboprost tromethamine

A
  • “Hemabate”
  • Synthetic analogue of PGF2alpha
  • Upregulates oxytocin receptors and gap junctions in myometrium to promote contractions
  • Used for:

*2nd trimester abortion

*PPH caused by uterine atony if oxytocin doesn’t work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Prostaglandins Adverse Reactions

A
  • Uterine tachysystole (>5 contractions in a 10min period); check for fetal heart rate abnormalities
  • GI disturbance- N/V, diarrhea
  • Transient fever
  • Retained placental fragments
  • Excessive bleeding
  • Decrease diastolic BP
  • Headache
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Prostaglandin cautiously used in patients with

A
  • Asthma
  • Cervicitis
  • Vaginitis
  • Inc. or dec. BP
  • Anemia
  • Jaundice
  • Diabetes
  • Epilepsy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Prostaglandins Contraindicated in patients with

A
  • Acute PID
  • Drug hypersensitivity
  • Active renal, hepatic or CV disorders
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Oxytocin

A
  • Most common induction agent

*so common that “oxytocis” is often used synonymously w/ uterotonics

*Pitocin, Sytocinon

  • Hormone made in hypothalamus (paraventricular n.)
  • Stored in and released by posterior pituitary
  • Short plasma t1/2; 3-6min.
  • Cannot be given orally; degraded by GI enzymes
  • By end of pregnancy, OT receptors increase 300 fold
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Oxytocin uses in pregnancy/labor

A
  • Labor induction, but variable responses

*not always successful, but still the best thing we have for labor induction (works best following PGE)

*maximal effective dose is diff. pt to pt

  • Labor augmentation
  • Following incomplete abortion after 20wks gestation
  • After delivery to prevent/control uterine hemorrhage
  • In high doses to induce abortion

- Inappropriate use can lead to uterine rupture, anaphylaxis, or maternal death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Oxytocin MOA

A
  1. Inc. IP3 mediated Ca2+ release from SR
  2. Inc. freq. of APs, thus inc. Ca2+ entry thru VGCCs
  3. Inhibits Ca2+ efflux
  4. May directly inhibit MLCP
  5. Stimulates release of PGE2 and F2alpha
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Oxytocin Risks and Adverse Effects

A
  • Uterine hyperstimulation- risk may be increased w/ PGE+OT

*tachysystole (>5 contractions in 10min. over a 30min. window)

*hypertonus (contraction lasting >2min.)

  • Uterine rupture
  • Amniotic fluid embolism
  • Fetal distress
  • Hypernatremia/H2O intoxication w/ prolonged use (secondary to ADH-like effects of oxytocin); rare, but can lead to convulsions, coma, death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Mifepristone (RU-486)

A
  • Competitive progestin antagonist in the presence of progesterone
  • Induces uterine contractions by causing progesterone withdrawal
  • Sensitizes uterus to contractile prostaglandins
  • +prostaglandin (misoprostol) = abortifacient in early pregnancies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Ergots

A
  • Produced by a fungus that causes disease in plants
  • Aides in the reduction of postpartum blood loss
  • Postpartum and postabortal atony and hemorrhage
  • Generally not first-line treatment
  • Not for long-term use (2-3days, 7 max)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Methylergonovine

A
  • Ergot like derivative
  • Directly stimulates uterine smooth muscle

*inc. muscle tone

*enhances rate and force of rhythmical contraction

  • Induce arterial vasoconstriction
29
Q

Methylergonovine MOA

A
  • Partial agonist of alpha-adrenergic receptors
  • Some 5-HT (serotonin), dopamine receptor activity
  • Inhibits the release of EDRF (endothelial-derived relaxation factor)
30
Q

Methylergonovine Adverse Reactions

A
  • Hypertension (b/c of alpha-adrenergic actions)
  • Headache
  • Seizures?
  • N/V
  • Chest pain
  • Difficulty breathing
  • Can affect lactation due to effects on prolactin
  • Leg cramps

- Prolonged use leads to ergot poisoning including gangren in the nursing infant

*signs include severe uterine cramping, CV changes, cyanosis, muscle pain, tingling and other signs of impaired peripheral circulation

31
Q

Methylergonovine Contraindications

A
  • Angina pectoris
  • MI
  • History of CV accident, transient ischemic attack or hypertension (b/c potential for seizures arrhythmias, CVA or MI)
32
Q

Tocolytics Effects and Limitations

A
  • Once labor starts, none of these drugs can hold off labor for more than 7 days; most only 48hrs max
  • Provides enough time to:

*give antenatal corticosteroids to get fetal lungs producing surfactant

*get mom to a facility w/ proper lvl NICU

  • ~20% of cases, hydration and bed rest may suffice to stop contractions
33
Q

Tocolytic Agents Contraindications

A
  • Intrauterine fetal demise
  • Lethal fetal anomaly
  • Nonreassuring fetal status
  • Preeclampsia w/ severe features or eclampsia
  • Maternal hemorrhage w/ hemodynamic instability
  • Intraamniotic infection
34
Q

Progesterone

A
  • Tocolytic
  • Preventative only- must be given early in pregnancy
  • Will not help once preterm labor begins
  • Maintains uterine quiescence
  • Silences myometrial contractility
  • Promotes cervical competency
  • Hyperpolarizes uterine smooth muscle membranes
  • Progesterone withdrawal—> parturition triggering
35
Q

17alpha-hydroxalase

A
  • Enzymes that placenta lacks
  • Converts progesterone to estrogen

*b/c placenta lacks this, progesterone is kept at consistent lvls

*placenta makes estrogens from fetal androgens (E3 is main pregnancy estrogen)

36
Q

Progesterone MOA

A
  1. Dec. Ca2+ entry and release from SR
  2. Can act thru nuclear and membrane PRs to alter gene expression, dec. contractibility of myometrial cells (preventing gap junctions)
  3. Membrane PRs couple to Ca2+ signaling pathways
  4. Inhibits PG synthesis
  5. May inhibit OT binding to receptor
37
Q

Progesterone as preventative therapy for premature labor

A
  • 17 alpha-hydroxyprogesterone caproate (17-OHPC)
  • Weekly IM injection starting week 16-20 until 36
  • Helps to maintain progesterone lvls needed for uterine quiescence
  • Approved by FDA to “reduce the risk of preterm delivery before 37wks…in women w/ a history of at least 1 spontaneous preterm birth”

- NOT effective in women pregnant w/ multiples

38
Q

Progesterone Side Effects

A
  • Blood clots
  • Depression
  • GI issues (nausea, diarrhea)
  • Local reactions to shots
39
Q

Progesterone Contraindications

A
  • Blood clots/clotting problems
  • Breast cancer or history
  • Liver problems
  • Uncontrolled high BP
40
Q

MgSO4

A
  • Often the first-line tocolytic in USA, though treating premature labor is an off-label use
  • Approved to prevent seizures in preeclampsia
  • Thought to be relatively safe for mom and fetus if used no longer than 5-7 days
  • May provide neuroprotection to preemie (dec. risk of cerebral palsy
  • IV admin.
41
Q

MgSO4 MOA

A
  • Not completely clear, but likely:
  • Antagonizes/competes w/ Ca2+
  • Dec. extracellular Ca2+ entry and release of Ca2+ from SR
  • Inc. Ca2+-dependent ATPase (promotes Ca2+ uptake by SR)
  • Activates adylate cyclase
  • Inc. Nitric oxide synthase
  • Overall effect is relaxation of smooth muscle
42
Q

MgSO4 Adverse Effects

A
  • May see signs of Mg2+ toxicity after 5.5mEq/L
  • Life threatening Mg2+ toxicity can be counterd w/ calcium gluconate
  • Fetal signs = low apgar scores or hypotonia
  • Bone abnormalities in fetuses w/ >5 days MgSO4 exposure
43
Q

Calcium Gluconate

A
  • Counters life threatening Mg2+ toxicity
44
Q

MgSO4 Contraindications

A
  • Myasthenia gravis
  • Myocardial compromise
  • Cardiac conduction defects
  • Impaired renal function can increase likelihood of Mg2+ toxicity
45
Q

Nifedipine

A
  • Ca2+ channel blocker most commonly used for tocolysis
  • One of the longest-acting tocolytics (can delay labor for ~7days)
  • Optimal dosing is not establish

*t1/2 = 2-3hrs

*duration of action (PO) = 6hrs

  • Almost completely metabolized by liver; excreted by kidney
46
Q

Nifedipine Adverse Effects

A
  • Peripheral vasodilator

*nausea, flushing, headache, dizziness, palpatations

*some reports of hypotension, but not as much CV impact as other drugs (beta-agonists)

  • Respiratory depression may occur in women also taking MgSO4
47
Q

Nifedipine Contraindications

A
  • Hypersensitivity to Ca2+ channel blockers
  • Hypotension
  • Preload
  • Use with care in women with:

*left ventricular dysfunction

*CHF

48
Q

Anti-oxytocins

A
  • Competitive antagonists at OTRs

*blocks pathway that causes release of intracellular Ca2+

49
Q

Atosiban

A
  • Anti-oxytocin
  • Competitive inhibitors of OTRs and vasopressin V1a receptors
  • Questionable efficacy
  • Not approved for use in USA, but used in Europe
  • IV admin.
50
Q

Beta-adrenergic agonists

A
  • B2-AR agonists
  • Activates adenylyl cyclase—> inc. cAMP—>activtes PKA
  • Inactivates MLCK
  • Decreases Ca2+
51
Q

Terbutaline

A
  • Off-label
  • Beta-adrenergic agonist
  • Can only hold off preterm labor for 48-72hrs, which is fine b/c…
  • NOT FOR PROLONGED USE in pregnant women (beyond 48-72hrs); can be fatal
  • Risk of post-partum hemorrhage b/c B2-AR agonists occupy receptor for a long-time (thus oxytocin will be ineffective)
52
Q

Indomethacin

A
  • Prostaglandin synthesis (COX) inhibitor
  • NSAID (like motrin)
  • Most commonly used COX inhibiting tocolytic
  • Cannot be used for more than 2-3 days, but not effective for longer than that anyway
53
Q

Indomethacin MOA

A
  • Decreases PG production in myometrium
  • Many PGs in uterus are uterotonics, so these drugs decrease contractions
  • May inhibit both isoforms of COX (1 and 2)
54
Q

Indomethacin Maternal Adverse Effects

A

Side effects of nonspecific COX inhibitors

  • Nausea
  • Esophageal reflux
  • Gastritis
  • Emesis
  • Platelet dysfunction

Side effects of COX2 inhibitors

  • Reduced severity of GI adverse effects

- Boxed warning for CV outcomes such as stroke

55
Q

Indomethacin Fetal Adverse Effects

A

COX inhibitors in fetus:

  1. Premature closure of ductus arteriosus
    - Can lead to primary pulmonary hypertension
    - Dependent on:

*duration of exposure (ex, indomethacin exposure >48hrs)

*gestational age

+most common after 31-32wks

+Indomethacin NOT recommended for use after 32wks

  1. Oligohydramnios
    - Occurred in 70% of pts treated w/ indomethacin for >72hrs

*COX inhib—> dec. fetal urine—> dec. amniotic fluid

56
Q

Contraindications of COX inhibitors

A
  • Platelet dysfunction
  • Bleeding diabetes
  • Hepatic dysfunction
  • GI ulcers
  • Renal dysfunction
  • Asthma w/ hypersensitivity to aspirin
57
Q

Galactogogues

A
  • Lactation stimulators
  • Used to induce, maintain, and increase milk production
  • Often needed after preterm labor
58
Q

Herbal supplements thought to be galactogogues

A

- Fenugreek

  • Fennel
  • Goat’s rue
  • Asparagus
  • Anise
  • Milk thistle
59
Q

Drugs to stimulate lactation

A
  • Stimulates synthesis and release of prolactin by antagonizing dopamine D2 receptors
  • Many are antipsychotics
  • Most common pharmaceutical galactogogues are:

*Metoclopramide

*Domperidone (banned in USA, used in Canada)

*Chlorpromazine

60
Q

Metoclopramide

A
  • Stimulates lactation
  • t1/2 = 156.7min
61
Q

Metoclopramide adverse effects in mothers

A
  • Anxiety
  • GI disorders
  • Insomnia
  • Severe depression
  • Seizures
62
Q

Metoclopramide adverse effects in infants

A
  • Intestinal discomfort
63
Q

Domperidone

A
  • Stimulates lactation
  • not approved by FDA b/c was assoc. w/ cardiac arrhythmia and sudden death in moms
  • Additonal ADRs in moms: dry mouth, GI disorders
  • No ADRs in babies
  • Newer studies have found diff. results (no serious ADRs in moms)
  • t1/2 = 7.5hrs
64
Q

-Chlorpromazine

A
  • Stimulates lactation
  • t1/2 = 16-30hrs
65
Q

Chlorpromazine adverse effects in mothers

A
  • Weight gain
  • Movement disorder (Tardive dyskinesia, pseudo-parkinsonism)
66
Q

Chlorpromazine adverse effects in babies

A
  • Lethargy
  • Reduced behavioral performance
67
Q

Cabergoline

A
  • Drug to suppress lactation
  • Specific D2 receptor agonist
  • Used primarily for prolactinomas
  • >600ug dose within 24hrs of delivery very effective in stopping lactation
  • Side effects may be a concern

*simlar to bromocriptine, which causes hypertension, stroke, seizures and psychosis when used to stop lactation

*cabergoline thought to be safer, but not enough data

68
Q

Lactation Proccess Chart

A

RGU Exam 2 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions