From the Guidelines
Propranolol dosing during pregnancy should be individualized, with typical starting doses ranging from 10-40 mg taken orally two to three times daily, and the maximum daily dose generally not exceeding 320 mg. According to the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for the management of hypertrophic cardiomyopathy 1, most beta blockers, including propranolol, are generally considered safe to use during pregnancy. However, closer monitoring of fetal growth and surveillance for fetal bradycardia may be considered for pregnant women on beta blockers.
Key considerations for propranolol use in pregnancy include:
- Starting with lower doses, especially for hypertension, and adjusting as needed
- Monitoring blood pressure and fetal growth regularly
- Being aware of potential side effects such as fetal bradycardia, hypoglycemia, or growth restriction, particularly at higher doses
- Weighing the benefits of treating maternal conditions against potential risks to the fetus
It's also important to note that propranolol crosses the placenta, and newborns should be monitored for hypoglycemia and bradycardia for 24-48 hours after birth if the medication is used near delivery. A multidisciplinary care team, including cardiologists and maternal-fetal medicine specialists, can provide comprehensive management of pregnant women with conditions requiring propranolol, as suggested by the guideline 1.
From the Research
Propranolol Dosage for Pregnant Patients
The recommended dosage of propranolol for pregnant patients varies depending on the specific condition being treated.
- For hypertension in pregnancy, propranolol was administered at a dosage of 40 to 160 mg/day alone or in combination with diuretics, with blood pressure controlled in 17 of 19 patients taking propranolol alone and in 6 of 7 taking propranolol with diuretics 2.
- In the case of fetal tachycardia in diabetic pregnancy, a daily dose of 160 mg of propranolol was used to achieve a fetal heart rate of 120 to 160 beats/min 3.
- For anti-hypertensive therapy during pregnancy and lactation, a dosage of 40 mg daily was used without complication 4.
- Studies on the pharmacokinetics of propranolol during pregnancy have used dosages of 120 mg orally or 10 mg intravenously, with no significant alterations in elimination half-life, clearance, or apparent volume of distribution per kilogram antenatally compared with postnatally 5.
- Concentration-effect modelling with propranolol has also been studied, with a dosage of 10 mg given intravenously to determine the influence of pregnancy on drug action, showing that pregnancy can significantly alter drug effect in the absence of any pharmacokinetic changes 6.
Key Findings
- Propranolol dosages for pregnant patients range from 40 to 160 mg/day for hypertension and 160 mg/day for fetal tachycardia.
- The drug has been shown to be effective in controlling blood pressure and reducing fetal wastage in pregnant patients with hypertension 2.
- Propranolol has also been used safely during lactation, with estimated daily intake of propranolol in breast milk by the infant being about 3 micrograms 4.
- The disposition of propranolol is not altered during pregnancy, but pregnancy can significantly alter drug effect in the absence of any pharmacokinetic changes 5, 6.