Drugs Acting on the Uterus Flashcards
1
Q
Hormones and chemical that contract uterus
A
- Estrogens
- Prostaglandins
- Oxytocin
- Stretching
2
Q
Hormones and chemicals that relax uterus
A
- Beta adrenergic drugs
- Progesterone
- Alcohol
- MgSO4
3
Q
What is the primary cause of all PPHs?
A
Uterine atony
4
Q
1st line treatment PPH
A
Massage
5
Q
Oxytoxin (Pitocin, Syntocin)
A
-Cyclic octapeptide stored in posterior pituitary normally released in response to suckling and cervical pressure
6
Q
Oxytocin Indications/therapeutic effects
A
- DOC to induce labor at term if indicated**
- For prevention of hemorrhage (IM preferred)**
- For stimulation of milk let down reflex
7
Q
Oxytocin to induce labor
A
- Augment labor in selected patients w/uterine dysfunctional inertia
- Causes timed contractions (on then off)
- IV infusion is preferred for these
8
Q
Oxytocin adverse effects
A
- Water intoxication w/convulsions*
- Uterine rupture w/large dose*
- Allergy
- Anaphylaxis*
- Sinus bradycardia of the fetus*
(premature ventricular contractions and other arrhythmias of the fetus and fetal death due to extreme uterine contractions, etc.)
9
Q
Why does water intoxication occur?
A
- Because of the ADH like effect of oxytocin
- Serious complication that may occur
- If doses are large and infused for a prolonged period
10
Q
Oxytocin pharmacokinetics
A
- Very short half life: 1-6 minutes
- Inactivated by liver and kidneys
11
Q
Oxytocin contraindications/precautions
A
- Malpresentation
- Cephalopelvic disproportion
- Complete placenta previa
- Uterine scar from previous C-section
- Unengaged head
- Cervical scarring
12
Q
Ergot alkaloids (ergonovine maleate, methylergonovine maleate) MOA
A
-Contraction of uterine smooth muscle through activation of serotonin and alpha-adrenergic receptors
13
Q
Ergot alkaloids indications/therapeutic effects
A
- After completion of labor and the delivery of the placenta* to produce firm uterine contractions and to decrease uterine bleeding
- 2nd line after massage and oxytocin have failed
- For the same reason following suction abortion
14
Q
Ergot alkaloids pharmacokinetics
A
- Rapid action
- 30-40 seconds after IV
- 10 min after oral use
- Action lasts several hours
15
Q
Ergot alkaloids adverse effects
A
- Transient HTN (contracts ALL smooth muscle)
- Angina, MI
16
Q
Ergot alkaloids contraindications/precautions
A
- Should NEVER be used to induce labor* (the contractions are strong, non-physiological, continuous and will cause fetal hypoxia)
- Obliterative vascular or coronary artery disease*
17
Q
Prostaglandins (dinoprostone; synthetic prostaglandin E2) Indications/therapeutic effects
A
- Expulsion of uterine contents (intrauterine fetal death, missed abortion [miscarriage], elective abortion)
- Cervical ripening prior to delivery at term
18
Q
Dinoprostone pharmacokinetics
A
- For abortion: one suppository inserted in the vagina. Subsequent suppositories inserted at 3-5 hour intervals until abortion occurs
- For cervical ripening: apply gel to cervix
19
Q
Dinoprostone adverse effects
A
- GI disturbances, vomiting, diarrhea***
- Black box**
- Fever, chills, HA
20
Q
Dinoprostone contraindications/precautions
A
- For cervical ripening, problems w/mother or fetus (fetal distress, etc.; hx of difficult deliveries or C-section)
- For abortions-should NOT be used in patients with: acute pelvic inflammation; acute cardiac, pulmonary, renal, or hepatic diseases; asthma, HTN, anemia, jaundice, or epilepsy
21
Q
Prostaglandins-Carboprost tromethamine (Prostin/M15, Hemabate)
A
-This is a derivative (15-methyl) of PGF2 alpha
22
Q
Carboprost tromethamine indications/therapeutic effects
A
- Induce abortion in 13th and 20th week (2nd trimester; time of abortion is 16 hrs)
- Postpartum bleeding due to uterine atony (3rd line after massage, oxytocin, and ergots)
23
Q
Carboprost tromethamine pharmacokinetics
A
- IM administration
- Methylation increases half life from 15 seconds to 8 minutes
24
Q
Carboprost tromethamine adverse effects
A
- Not serious if used properly
- Systemic PG actions often diagnosed as anaphylactic shock
- Vomiting and diarrhea**
- Fever and rashes
25
Carboprost tromethamine contraindications/precautions
-Should NOT be used in patients with-acute pelvic inflammation; acute cardiac, pulmonary, renal, or hepatic diseases; asthma, HTN, anemia, jaundice, or epilepsy
26
Uterine relaxants (tocolytics) goal
To prevent premature labor or delay premature labor until term or until the fetus has matured sufficiently for survival (37th week)
27
What happens if delivery happens before the 37th week?
-If the fetal lungs are developed-->corticosteroids
28
Tocolytics other info
- No option is FDA approved, or a DOC**
- Doesn't look like their use improves perinatal outcome
- May prolong enough to give corticosteroids (2-7 days)
29
Magnesium sulfate (MgSO4) MOA
-Unknown (relaxes the uterus probably by a direct effect)
30
MgSO4 indications/therapeutic effects
- Considered 1st line drug
| - Can prevent convulsions in pre-eclampsia and treat eclampsia (FDA approved)
31
MgSO4 pharmacokinetics
-IV, administered slowly (significant hypotension or asystole if too fast)
32
MgSO4 adverse effects
- Flushing, diaphoresis, hypotension
- Depressed deep tendon reflexes, muscle paralysis, weakness, lethargy, hypothermia
- Circulatory collapse, and cardiac, CNS, or respiratory depression
33
Nifedipine (Procardia) MOA
- L type calcium channel blocker
| - Inhibits Calcium influx (smooth muscle contractions)
34
Nifedipine indications/therapeutic effects
-Becoming 1st line agent (considering beta 2 agonists problem)
35
Indomethacin
- Has been investigated for its ability to delay preterm labor
- 1st-2nd line drug
36
Indomethacin MOA
-Strong inhibitor of COX enzyme-->reduction of prostaglandin synthesis
37
Indomethacin adverse effects
- Maternal GI irritation, peptic ulceration, thrombocytopenia, allergic reactions, HA, and dizziness
- Reports about partial closure of the fetal ductus arteriosus** (also impaired fetal renal function, bronchopulmonary dysplasia, and persistent pulmonary HTN in the neonatal period)
38
Progesterone
"recommended" by the American College of Obstretricians and Gynecologists
39
Progesterone indications/therapeutic effects
- More effective than placebo in maintaining the length of pregnancy when given prophylactically* from the 16th-37th week of pregnancy or until delivery
- Not effective for acute treatment**
- Recommended for high risk women with a hx of preterm birth
- Approved for use in ART to maintain the luteal phase following IVF or ICSI
40
Nitroglycerin
-Emergency use only**-in case of uterine rupture
41
Nitroglycerin indications/therapeutic uses
-Case reports have shown that when given IV bolus intravenous nitroglycerin, there is a sudden transient cervicouterine relaxation within 45-90 seconds, lasting about 1 minute
42
Nitroglycerin contraindications/precautions
- Uncorrected hypovolemia
- Severe anemia
- Increased intracranial pressure
- Constrictive pericarditis/pericardial tamponade
- Hypersensitivity
43
Ethanol
-Historically used in rural areas
44
Ethanol MOA
-Direct relaxant effect on the myometrium and inhibition of oxytocin release
45
Ethanol indications/therapeutic effects
Inhibit premature labor
46
Ethanol Pharmacokinetics
-Loading dose (10% injection): 7.5 ml/kg/hr IV for 2 hours w/a maintenance infusion rate of 1.5 ml/kg/hr IV for put to 10 hrs.
47
Beta 2 adrenergic agents-terbutaline (brethine)
-FDA black box warning against its use in tocolysis
