UKMi Q&A xx - SPS



Q&A 162.3

How can nausea and vomiting be treated during pregnancy?

Prepared by UK Medicines Information (UKMi) pharmacists for NHS healthcare professionals

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Published: April 2014

Summary

□ Most cases of nausea and vomiting in pregnancy resolve within 16-20 weeks with no harm to the pregnancy.

□ Prescribing treatment in the first trimester is usually not indicated unless the symptoms are severe and debilitating.

□ NICE recommend that non pharmacological treatments should be tried first, such as changes in diet, use of ginger or wrist (P6) acupressure.

□ No drug is specifically licensed for the treatment of nausea and vomiting in pregnancy though some anti-emetics are considered compatible with pregnancy.

□ First line recommended treatment is an antihistamine such as promethazine or cyclizine, both of which can cause sedation.

□ Second line treatments are prochlorperazine and metoclopramide.

□ There is a growing body of evidence of the use of ondansetron in pregnancy, which generally show no increased incidence in the risk of major malformations and other pregnancy outcomes, but other anti-emetics, such as anti-histamines, should be tried first.

□ This Medicines Q&A does not discuss treatment of severe nausea and vomiting in pregnancy, or hyperemesis gravidarum, which affects around 1% of pregnant women. These cases should be managed in hospital by specialists.

Limitations

□ Much of the data on teratogenicity come from retrospective, cohort or registry-based studies. These studies are not designed to specifically address foetal safety and there may be flaws in the quality and completeness of the data.

□ Assumptions are made in registry studies that the dispensing of a prescription means that the pregnant woman took the drug, but adherence to treatment and timing of treatment is not confirmed and none address the fact that the woman may be taking additional medication.

□ Studies and reports vary in the outcomes reported; some evaluate whether nausea and vomiting were adequately treated without reporting pregnancy outcomes, others will state pregnancy outcomes but not if NVP was well-controlled.

□ Maternal adverse events may or may not be included.

□ Summaries of Product Characteristics of the medicine mentioned in this Q&A vary in their recommendations regarding the use each specific medicine in pregnancy.

This Q&A does not discuss the treatment of hyperemesis gravidarum, a disorder in around 1% of pregnant women in whom fluid and electrolyte disturbances or nutritional deficiency from intractable vomiting develops in early pregnancy (1). This condition usually requires hospital admission for intravenous fluids, electrolyte replacement and sometimes nutritional support (1). This Q&A does not discuss the use of combinations of anti-emetics or of drugs used that are not normally part of the treatment pathways, such as nabilone or haloperidol.

Background

Nausea and vomiting are common symptoms in pregnancy, affecting more than half of all pregnant women and are mainly caused by human chorionic gonadotropin (HCG) produced by the placenta (1-3) Symptoms usually begin at around gestational weeks 4-8 and may peak between weeks 7 to 12, when HCG levels are at their highest, before subsiding at around week 16 (1-5). Some women continue to experience symptoms up to or beyond week 20 (1;6). Although it is often referred to as ‘morning sickness’, nausea and vomiting of pregnancy (NVP) can occur any time of the day. Only 11-18% of affected women have sickness confined to just the mornings (7). Nausea and vomiting do not have harmful effects on the pregnancy but the pregnant woman’s quality of life can be severely affected, with day-to-day activities hampered, greater use of healthcare resources and time off work (1).

Hyperemesis gravidarum affects around 1% of all pregnancies (1). It refers to pregnant women in whom fluid and electrolyte disturbances or nutritional deficiency develops from intractable vomiting early in pregnancy (7).

Answer

Both non-pharmacological and pharmacological measures are used to treat nausea and vomiting of pregnancy (NVP). Because NVP occurs primarily in the first trimester, when organogenesis is taking place, teratogenic effects of drug treatments are of concern (8). If pharmacological treatment for nausea and vomiting during pregnancy is used, the drugs should be taken regularly to achieve adequate blood concentrations. If oral preparations cannot be tolerated, then other administration routes can be used. The different drugs can be taken in combination. There is limited evidence regarding the safety and efficacy of most drug therapies, including anti-emetics, during pregnancy, but available studies and extensive clinical experience support the efficacy, safety and rationale for using treatment options that are available and used in clinical practice (9). Drugs may be prescribed when the potential benefit justifies the potential foetal risk, without evidence of harm (9). Medicines Q&A 34 has advice on what needs to be considered when prescribing to pregnant women.

Non-pharmacological measures

There are a number of non-pharmacological measures that may help initially, though there is little published evidence regarding the efficacy of dietary changes (1;4):

• Ensure good hydration, at least 2L of water a day

• Eat little and often, mainly bland foods

• Prevent a full stomach and avoid large meals and high fatty foods

• Between-meal snacks should be nuts and high-protein foods

• Eat simple dry crackers or biscuits before getting out of bed in the morning

P6 (wrist) acupressure

Wrist acupressure is a non-invasive method of treating nausea. A number of randomised controlled trials have studied the efficacy of P6 (wrist) acupressure in pregnancy. All but one of the studies showed a positive effect for stimulation of the P6 pressure point and a reduction in nausea and vomiting; the remaining study showed no difference between acupressure and no treatment. No difference in adverse foetal outcomes (perinatal outcome, congenital abnormalities, pregnancy complications) were seen between acupressure, sham acupressure and no treatment (7).

Drug treatment

Drug treatment of nausea and vomiting in pregnancy often coincides with the period during which the foetus is most susceptible to teratogenic effects: organogenesis occurs during the 4th to 10th gestational weeks (2;10). The choice of drug will be based on its adverse effect profile as well as its safety in pregnancy. Factors such as patient preference and preparations available may also play a part when choosing a drug. When evaluating the effects of a drug in pregnancy, efficacy as pregnancy outcomes should be taken into consideration.

There are a number of medicines that can be used to treat NVP, such as cyclizine, promethazine, prochlorperazine, metoclopramide and ondansetron, as well as complementary medicines such as ginger and pyridoxine. Table 1 provides an overview of the preparations available and standard dosing regimens of the antiemetics discussed in this Q&A.

Routes of administration

Table 1: Drugs available for treating nausea and vomiting and doses for licensed indications

|Drug |Licensed indications |Dose |Preparations available |

| | | |(11) |

|Cyclizine (11) |Nausea and vomiting. |Orally or by IM or slow IV injection: 50mg up to three times a day |Tablets, injection |

|Domperidone (12) |Nausea and vomiting. |Maximum duration of treatment: one week. |Tablets, liquid, |

| | |Doses for adults and adolescents ≥35kg: |suppositories. |

| | |Orally 10mg three times a day, maximum 30mg/day | |

| | |Suppository: 30mg twice a day, maximum 60mg/day. | |

|Promethazine |Nausea and vomiting. |Orally: 20-25mg twice a day |Tablets, liquid, |

|hydrochloride (11;13) | |IM injection: 25-50mg, max 100mg/day |injection |

|Prochlorperazine (11) |Severe nausea and |Oral tablets: Acute attack: 20mg initially then 10mg after 2 hours; |Tablets, liquid, |

| |vomiting. |prevention: 5-10mg two - three times a day , max 30mg/day |intramuscular injection,|

| | |Buccal tablets: 3-6mg twice a day. |buccal tablets. |

| | |IM: 12.5mg stat followed by oral medication 6 hours later | |

|Metoclopramide (11) |Nausea and vomiting. |Maximum duration of treatment: 5 days. |Tablets, liquid, |

| | |Dose in adults >18 years of age and >60kg body weight: |injection |

| | |Orally or by IM or slow IV injection: | |

| | |10mg up to three times a day | |

| | |Dose in adults >18 years of age and ................
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