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Fall'20 Pharmacology III > Tocolytics > Flashcards

Flashcards in Tocolytics Deck (107)
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1

Define Tocolytic Drug :

Any drug use to suppress premature labor

2

Most Common tocolytics

1)Beta agonist (Ritrodrine or Terbutaline ) but use has declined due to maternal side effects
2)Magnesium

3

Maternal (6)side effects of tocolytics: ( TRHAMM)

1.Tachycardia
2.Rarely Pulmonary edema
3.Hyperglycemia + Hypokalemia
4.Arrhythmia
5.Myocardial Ischemia
6.Mild hypotension

4

Why use caution when using ephedrine and /or Ketamine ?

🤰🤰

5

Premature labor is inhibited until ___________and ___________. What medication is given , and a minimum of _________hours is required.

Until lung mature
And
Sufficient surfactant is produced .
Give steroids to induce production of surfactant
A minimum of 24- 48 hrs is required

6

When Tocolytic therapy fails , what becomes necessary

Anesthesia ( for delivery )

7

Terbutaline : routes, rapid route, duration of effects and MOA of that duration .

Routes: PO, SQ, Inhalation
Rapidly effective by SQ and Inhalation.
Effects persists 3-6 hrs partly bc its structure w/ a RESORCINOL ring preventing COMT action.
Bc of this ring , terbutaline cannot be methylated by COMT

8

When are the tocolytics Terbutaline and Ritodrine used and how is Ritodrine administered ?

used to manage premature labor contractions through relaxation of myometrium via their B2 effect .
Ritodrine started IV and continued PO if tocolysis is achieved

9

How is ritodrone metabolized

Liver
To inactive conjugated
1/2 is excreted unchanged on the urine

10

Continuous use of beta agonist prayer has been associated with:

hypokalemia and tachyphylaxis

11

What is the mechanism of hypokalemia in beta 2 agonists ?

Insulin mediated increase in uptake of extra cellular K+
or
Increased Na+/K+/ATPase activity .

12

Pulmonary edema with normal PCWP have been attributed to what medications?

Terbutaline and Ritodrine

13

All beta adrenergic Tocolytic drugs only have B2 receptor effects . True or False ?

False .
Both B1 and B2 receptor effects

14

Where are B2 receptors found ? ( PALSSS)

Pancreas
Adipose Tissue
Liver
Smooth muscle : Uterus, blood vessels , bronchi , intestine , detrusor , spleen
Skeletal muscle
Salivary glands

15

B2 Smooth muscles : name organs/locations

Uterus
Blood vessels
Bronchi
Intestine
Detrusor
Spleen

16

Ritrodrine and Terbutaline are relatively selective B2 and stimulation of B2 in the myometrium =

Relaxation of the uterine smooth muscle

Other B2 effects such as vasodilation occur as well ( can be undesired ) + some B1 effects

17

Where are Beta 1 receptors located ?

Predominantly: Heart and adipose tissue .
This results in increased maternal HR and CO ( can be undesired )

18

MOA Beta Adrenergic Tocolytic Drugs

Agonist>> Beta 2 site on outer membrane of uterine myometrail cells >>activate the enzyme adenyl Cyclase >> adenyl cyclase catalyzes conversion of ATP to cAMP>> rise in intracellular concentration of cAMP = high cAMP concentration >>decrease in available intracellular concentration of calcium + inhibits myosin light chain kinase (MLCK) >> inhibition of MLCK= decrease interaction between actin and myosin = myometrial relaxation

19

A delay of ____minutes often results in slowing of maternal HR after administration of Tocolytic drug . However ,______, ______and ________ often require anesthesia

15 minutes ;
Advanced labor , non reassuring FH status, and abnormal presentation often require anesthesia

20

Theoretically, what are the effects of epidural analgesia/anesthesia after beta adrenergic agonist when compared to spinal anesthesia ? And why ?

May cause less hemodynamic compromise than spinal anesthesia
Because of slowe onset of sympathetic blockade .
However this theory remains UNPROVEN

21

Aggressive hydration in patients on Tocolytic therapy . Any thought ?

Avoid aggressive hydration before and during induction of anesthesia in these patients
Due to :
Risk of pulmonary edema

22

GA is required in a patient who has recently received beta-adrenergic tocolysis , what agents will you avoid in order to prevent exacerbation of maternal tachycardia

Atropine
Glycopyrrolate
Pancuronium

* Maternal tachycardia may make it difficult to asses volume status and depth of anesthesia

23

Why is it a bad idea to use Halothane on patients on tocolysis ?

Because halothane sensitizes the myocardium to catecholamine-induced-arrhythmias

It should not be used

24

Why should hyperventilation avoided ?

It will exacerbate the hypokalemia = hyperpolarization of the cell membrane will be potentiated

25

A study found what effects of terbutaline pretreatment in non-pregnant patients on Succs neuromuscular blockage ?

The terbutaline pretreatment shortened BOTH onset time and recovery time of succs- induced-NMB. Therefore :
May be pro dent to use a nerve stimulator during GA

26

What are the MOA of Magnesium :

1. Extra cellular Mag = competitive antagonist of calcium either at the motor end plate or cell membrane>> reducing calcium influx into the myocyte .
2. Competes with Ca++ for low affinity calcium-binding sites on outside of the sarcoplasmic reticulum and prevents the rise in free intracellular calcium concentration.
To sum it up :

1. Reduce calcium influx into the myocyte
2.Prevent rise in free intracellular calcium concentration

27

Hypermagnesemia result in

1) Abnormal neuromuscular function
2) Decrease the release of acetylcholine at the NMJ + decrease the sensitivity of the end plate to acetylcholine

28

True or False . Per studies , Mag Sulfate results more frequent and more severe CV side effects than beta adrenergic tocolytic agents

No !
Mag Sulfate = less severe and less frequent CV side effects than Tocolytic

29

Magnesium can have similar effects of beta adrenergic tocolytic agents .what side effects have been reported ?

1.Chest Pain And Tightness
2.Palpitations
3.Nausea
4.Transient hypotension
5.Blurred vision
6.Sedation
7.Pulmonary edema
8. May lessen normal compensatory responses to hemorrhage in the mother AND fetus

30

How is Magnesium is eliminated

Almost entirely by renal excretion