IPFC 1 - Pregnancy: Nausea and Vomiting

Nausea and vomitting in pregnancy onset and peak

Most common medical condition of pregnancy:

- affects 70% of pregnant women

- onset 4-6 weeks

- peaks 9-12 weeks

When does n/v typically subside

20th week

- 80% stop by 12 weeks

- 20% continue into 3rd trimester

Severe NVP is called...

hyperemesis gravidarum

- debilitating, hospitalization, dehydration, parenteral nutrition

- affects 1.5% of women

Etiology of pregnancy N/V

Various theories:

- Psychological predisposition

- Impaired gut mobility

- Hormonal stimulis (hCGlevels, rising estrogen levels)

Risk Factors of n/v

- Increased placental mass:

- Multiple gestation

- advanced molar gestation

- Family history

- Previous NVP pregnancy

- History of motion sickness

- Migraines

- History of nausea from estrogen based meds

- Heartburn or GERD

- Supertasters

- Lack of multivitamin pre- conception/early pregnancy

Hyperemesis Gravidarum Presentation:

- persistent vomiting not related to other causes

- measure of acute starvation (ketosis can occur); risk of hypovolemia

- some discreet measure of weight loss, most often >5% of pre-pregnancy weight

- electrolyte, thyroid, and liver abnormalities sometimes

What is the most common Indication for admission to the hospital in early pregnancy

Hyperemesis Gravidarum (HG)

- Second only to preterm labour

Until the 1930s, severe HG symptoms were a cause of maternal death due to:

• Wernicke’s encephalopathy

• Splenic avulsion

• Esophageal rupture

• Pneumothorax

• Acute tubular necrosis

• Other concerns: Psychological symptoms (depression), LBW infants

What is essential in the management of HG

Early Management

• 35% experience clinically significant symptoms and 10% require medication

• Management more difficult once symptoms NVP progress

What are the biggest factors to influence clinical decision making

Woman's perception of the severity of symptoms and desire for treatment

Goals of treatment of NVP

Avoid

• Hospitalization

• time off from work (QoL)

• difficulty caring for other children (QoL)

• psychological effects

• prevent progression to severe form of NVP

What to assess in a patient's history?

• nature of symptoms (nausea alone), severity, frequency (time of day, number of times)

• triggers (foods, odours,stress)

• Rule out underlying causes: PMH (infection, migraines, malignancy), bowel movements (constipation), changes in drug/supplement use

• What they have tried and willingness to try pharmacological treatment

What to check in a patient's physical assessment?

• Vitals, assess for dehydration, abdominal palpitation

• Labs (CBCs, T4/TSH, LFTs, SrCr, serum electrolytes)

• Imaging if required

Assessment tool for NVP

Norwegian PUQE score for assessing symptoms including quality of life question

Non-pharm strategies for NVP

1) Diet

2) Fluids

3) Acupressure and acupuncture (i.e. seabands) --> limited evidence

4) Ginger capsules may be helpful (up to 250mg QID)

5) Rest/sleep

Diet recommendations NVP

• Avoid mixing solids and liquids

• Eat whatever/whenever they can tolerate eating (in bed in morning)

• Smaller more frequent meals, avoid getting hungry

Fluids recommendation NVP

• 2 litres per day

• Small amounts frequently

• Cold fluids, popsicles

Iron recommendation NVP

Women experiencing nausea and vomiting of pregnancy may discontinue iron-containing prenatal vitamins during the first trimester and substitute them with folic acid or adult or children's vitamins low in iron

Step 1 Therapy NVP

Pyridoxine or Doxylamine/pyridoxine combination

Pyridoxine or Doxylamine/pyridoxine combination product

AKA Diclectin

• For mild-moderate nausea (NOT vomiting)

• available without Rx; good safety

• delayed release product

• sedation/dizziness

• take on empty stomach

Pyridoxine or Doxylamine/pyridoxine combination dosing and indication

Doxylamine 10mg/ pyridoxine 10mg = H1 receptor blocker + Vitamin B6

• 10-25mg q6-8 hours

1 tab AM, 1 tab noon, 2 tabs at night

MDD = 200 mg/day

Pyridoxine or Doxylamine/pyridoxine combination onset with vs without food

empty stomach (onset 4-6 hrs),with meal (onset 9-11 hours)

Bendectin

marketed in the USA, but removed because it was alleged to cause birth defects (not true), reintroduced as Diclegis

SOGC recommendation for Diclectin use

women with high risk for nausea and vomiting of pregnancy may benefit from preemptive doxylamine/pyridoxine treatment at the onset of pregnancy

T/F H1 receptor antagonists should be considered in the management of acute or chronic episodes of nausea and vomiting of pregnancy

True!

- Safety is well-studied in pregnancy and evidence suggests they

significantly reduce NVP

I.e. Dimenhydrinate (Gravol), diphenhydramine, promethazine

Step 2 when treating NVP

Add Dimenhydrinate

Dimenhydrinate

- Anticholinergic side effects (sedation, constipation)

- routes: IM, PO, PR

MDD = 200 mg/day of Dimenhydrinate when taking 4 Diclectin tabs

Step 3 when treating NVP

Add dopamine antagonist

Dopamine antagonists

Prochlorperazine (PO/PR),

Chlorpromazine (PO):

drowsiness, anticholinergic

Metoclopramide (PO/IV):

Limit to 5 day use due to risk of oculogyric crisis, diarrhea, cramping, sedation

Step 4 when treating NVP

Add Ondansetron + IV fluids

Ondansetron

• Serotonin 5-HT3 Receptor Antagonist

• for treatment of chemotherapy -induced N/V; not approved for use in pregnancy

• Has been used as last resort with anecdotal or small study data showing effectiveness.

Less sedating than other options

Step 5 when treating NVP

Methylprednisolone (IV)

Methylprednisolone (IV) and dosing

15–20 mg Q8H IV x 24H

- Corticosteroids in the first trimester has increased risk for cleft palate

- Additional BG monitoring in diabetics

5 steps of treating NVP (increasing severity)

1. Diclectin: Pyridoxine or Doxylamine/pyridoxine combination

2. Add H1 receptor antagonists (Dimenhydrinate)

3. Add dopamine antagonist

4. Odansetron + IV fluids

5. Methylprednisolone (IV)

Pharmacist Role in treating NVP

- find safest, most effective drug at lowest dose for shortest duration

- avoid duplicating drug classes when adding therapy (exception with doxylamine and dimenhydrinate)

- lowest ADR profile

- antihistamines generally bet tolerated

- tolerability of oral vs parenteral

NVP other measures that may help with therapy

1) Treat dyspepsia/GERD

• Calcium carbonate (TUMS®)

• H2 Blockers

• Proton Pump Inhibitors

2) Treat gas and bloating (i.e. simethicone, lactase)

3) Treat constipation (e.g. psyllium fibre, stool softeners)

Summary NVP

- generally starts 4-6 weeks and resolves by 12-16 weeks

- very common but severity varies

- impact on daily activities can be significant

- stepwise approach to medication (add-on if ineffective)

Which vaccinations are recommended in pregnancy?

Influenza, Pertussis (weeks 27-36)

Hep A/B if high-risk

COVID vaccine recommended

Which vaccinations to avoid in pregnancy?

live-attenuated vaccines (risk to fetus)

Non-pregnant women should be counseled to wait 4 weeks if given a live vaccine (i.e. MMR, varicella)

Can women who breastfeed can be immunized without restriction?

Yes

Zika virus

- Pregnant females can pass the virus to fetus which is transmitted by Aedes mosquitoes

- Fetal exposure to Zika can lead to neurological problems and severe birth defects, such as microcephaly.

- Can lead to increased risk of preterm labour and miscarriage

- Advise those looking to conceive and those pregnant to check travel advisories prior to travel