Antinausea Medications at 27 Weeks Gestation
At 27 weeks gestation, metoclopramide 5-10 mg orally every 6-8 hours is the preferred antiemetic, with ondansetron 4-8 mg every 8 hours as an alternative for refractory symptoms. 1, 2
First-Line Treatment Approach
Metoclopramide is the preferred agent at this gestational age, with an excellent safety profile throughout pregnancy and no significant increase in congenital malformations in large cohort studies. 1, 2
The recommended dose is 5-10 mg orally every 6-8 hours, which can be used safely throughout all trimesters. 1
Metoclopramide is particularly effective for moderate symptoms and has been validated as safe for use beyond the first trimester. 1, 3
Second-Line Options
Ondansetron (4-8 mg every 8 hours) can be used at 27 weeks gestation without the first-trimester concerns about cardiac and orofacial malformations. 1, 2
The small but statistically significant risks of orofacial clefts and cardiac defects associated with ondansetron are primarily relevant before 10 weeks gestation, making it safer at 27 weeks. 1, 2
Ondansetron has demonstrated efficacy across a range of symptom severity and is particularly useful for refractory cases. 3
Alternative Agents
Promethazine (12.5-25 mg every 4-6 hours) remains an option, though phenothiazines should generally be reserved for persistent vomiting. 4, 5
Vitamin B6 (pyridoxine) 10-25 mg every 8 hours can be continued if already initiated, though it is typically more effective in early pregnancy. 1, 2
The doxylamine-pyridoxine combination (10 mg/10 mg), while FDA-approved and first-line in early pregnancy, is less commonly needed at 27 weeks but remains safe if symptoms persist. 1, 2, 6
Critical Clinical Considerations
At 27 weeks gestation, you are well past the period of organogenesis (completed by 10 weeks), which significantly expands the safety profile of most antiemetics. 1, 2
Avoid corticosteroids unless absolutely necessary for severe hyperemesis, and if used, choose methylprednisolone or prednisolone which are metabolized in the placenta. 2
Do not use NK-1 antagonists (aprepitant) or second-generation antipsychotics (olanzapine) due to limited safety data in pregnancy. 2
Reassess the underlying cause if nausea persists at this gestational age, as nausea and vomiting typically resolve by week 20 in most pregnancies. 2
Practical Dosing Algorithm
Start with metoclopramide 10 mg orally every 6-8 hours as needed for nausea. 1
If inadequate response after 24-48 hours, add ondansetron 4-8 mg every 8 hours. 1, 3
For breakthrough symptoms, promethazine 12.5-25 mg can be added as rescue therapy. 4
Continue dietary modifications (small, frequent, bland meals) alongside pharmacotherapy. 1, 2