Anti-hypertensives in Pregnancy

Educational Materials

1. Use of anti-hypertensives in
Pregnancy
Associate Clinical Professor. Dr. Aisha M. El-Bareg
MBBS, DGO, MCCG, PCTM, MMedSci (ART), ABOG, MD, PhD
Senior Consultant in (Obs & Gyn)/ Reproductive Medicine
Faculty of Medicine, Al-Amal Hospital, Misrata .LIBYA

2. Classification of HTN in pregnancy
❖Pre-eclampsia & eclampsia syndrome
❖Chronic hypertension
❖Pre-eclampsia superimposed on chronic HTN
❖Gestational hypertension
❖Post-partum hypertension

3. Definition-Preeclampsia
❑Hypertension + proteinuria (classic definition)
❑Hypertension + multisystemic signs without
proteinuria (new addition)
–Thrombocytopenia (platelet count <100.000)
–Hepatic dysfunction (transaminases >2X )
–New renal insufficiency (s.cr >1.1mg/dl, or
doubling of s. cr in the absence of other renal
disease
–Pulmonary oedema
–New onset cerebral or visual disturbances

4. •Other signs and symptoms:
❑Oedema
❑Headache
❑Epigastric or RUQ abdominal pain
❑Sign of HELLP syndrome (variable presentation)
–Some do not have proteinuria
–Some are normotensive

7. Hypertension
Mild
•Systolic BP >140 mmHg or diastolic BP >90 mmHg
on 2 occasions at least 4 hrsapart while seated at
rest, after 20 weeks
Severe
•Systolic BP >160 mmHg or diastolic BP >110 mmHg
while seated at rest, after 20 weeks.

8. Antihypertensive medications are
prescribed with the goal of preventing
MATERNAL
consequences of severe hypertension (i.e.
prevention of cardiovascular and
cerebrovascular consequences like
intracerebral hemorrhages

9. The aim of starting these drugs isNOTto
reverse the primary pathologic process,
because these medications have never
been demonstrated to cure or reverse
preeclampsia

10. When to start ?
Canada: ≥ 140/90 mm Hg
USA: ≥160/105mmHg
Australia: ≥ 160/90 mm Hg
India: no consensus,
≥ 140/90, ≥ 150/100

11. Gradual reduction of BP to:
Systolic BP : 120-140 mmHg
Diastolic BP : 80-90 mmHg

13. α -methyldopa-mode of
actions:
•Centrally α-2 adrenergic agonist pro-drug which
metabolized into α-methyl norepinephrine that
stimulates presynaptic α-2 adrenergic receptors
to inhibit sympathetic outflow from vasopressor
centres in brain stem.
•Reduce peripheral vascular resistance , but CO is
not affected

14. ❖BP is gradually controlled over 6-8hrs because of
indirect mechanism of action
❖It is easily absorbed orally and reached peak level
in 4-6 hrs
❖It is completely excreted in urine over 12 hrs
❖It is also excreted in breast milk in small amount
and crosses placenta
α -methyldopa-mode of actions:

15. ❑Hepatic dysfunction
❑Pheochromocytoma
❑Depression
α –methyldopa –Contraindications:

16. α –methyldopa-Side effects:
•Maternal:
–Postural hypotension (reduce dose)
–Depression, headache
–Fatigue, drowsiness, nasal congestion
–False positive direct coomb’s test
–Abnormal liver function test
–Hemolytic anemia

17. α –methyldopa-Side effects:
•Rebound hypertension
•Due to intravascular volume expansion resulting
from salt and water retention has been reported
•If patient on long-term methyldopa develop
weight gain, edema, and rebound HTN, diuretics
should be added that would reverse these side
effects and increase UOP.

18. Loading dose : 250 mg
3-4 times a day up to a
max. of 2 g /day
Maintenance dose : 250 mg 3-4 times a day
α –methyldopa-Dosage

19. Hydralazine (Apresoline)
•MOA: direct vasodilators
•Advantage: rapid, improve
placental & renal blood flow,
no fetal side effect
•Disadvantage:tachycardia,
palpitation, headache,
flushing.

20. Administer 10 mg Nifedipin tablet orally
Monitor BP / 15 min
If after 45 min, sever HTN persist
Give second dose of 10 mg Nifedipin tablet orally
Monitor BP / 15 min until BP stabilises
If after 45 min (90 min from 1
st
dose), severe HTN
persist:
Dilute 20 mg Hydralazine in 20ml of water for inj
Administer 5mg (5ml) as an IV bolus
Monitor BP /10 min
If after 20 min severe HTN persist

21. Administer second dose of 5mg (5ml) Hydralazine
If after another 20 mins, same findings
Administer third dose of 5mg (5ml) Hydralazine
If severe HTN persist after 3 boluses of IV hydralazine
Draw 10 ml out of a 500ml normal saline bag, mix
the 10 ml with 80 mg hydralazine powder and
then load it back into the 500ml bag
Start hydralazine infusion via pump
at 30ml/hr, 5mg/hr
Increase infusion by 10ml/30 min to a max
90ml/hr(15mg/hr), aiming sys 140-160, dis 90-100

22. 5 or 10 mg IV Hydralazine over 2 minutese
20 minutes
10 mg IV Hydralazine over 2 minutes
20 minutes
20 mg IV Hydralazine over 2 minutes
20 minutes
40 mg IV Hydralazine over 2 minutes

23. Labetalol-mechanism of action:
➢Blocks β-1, -2 and α-1 sympathetic receptors
➢It mainly acts by decreasing peripheral
vascular resistance.
➢The cardiac output is not affected.
➢It has no effect on utero-placental blood
flow

24. Labetalol-contraindications:
❑Severe tachycardia
❑Pulmonary hypertension
❑Bronchospasm
❑Allergic disorders

25. Labetalol-side effects:
•Maternal:
➢Posturalhypotension,headache,angina,
drynessofmouth,fluidretention,andjaundice
•Fetal:
➢Ithasnoteratogeniceffect;ifgiveninhigh
dosecancauseneonatalhypoglycemia
➢Itissecretedinbreastmilkandcancause
decreaseinHRandBPoftheneonate

26. Labetalol-route & dosage

27. Labetalol-dose & route:
➢Oral dose of 100-200 mg every 8-12 hours
increasing frequency to 6 hourly till BP is
controlled
➢Maintenance dose of 200-400mg twice daily is
given

28. In acute situation:
20 mg IV Labetalol over 2 minutes
10 minutes
40 mg IV Labetalol over 2 minutes
10 minutes
80 mg IV Labetalol over 2 minutes

29. 10 minutes
80 mg IV Labetalol over 2 minutes
Repeat the same dose 2x after same interval
to achieve a cumulative max. dose of 300 mg
We can stop at any step if BP is controlled
10 minutes
It can also be give as IV infusion: 250 mg in 250
ml of NS at a rate of 20mg/hour (20ml/min)

30. ❖Ca-channel blocker-acts on arteriolar
smooth muscle-vasodilatation
Nifedipine (Adalat)

31. Nifedipine (Adalat) –side effects:
❖Tachycardia, palpitations, peripheral edema,
headaches, flushing.
❖Risk of neuromuscular blockade, myocardial
depression, and hypotension when combined
with magnesium .
❖Sublingual preparations associated with MI and
death

32. Nifedipine (Adalat) –dosage:
10 mg PO initial dose
20 minutes
20 mg if initial dose is not effective
20 minutes
20 mg IV Labetalol over 2 minutes
•
40 mg PO and obtain emergency
consultation if not effective
20 minutes