Lipid-lowering medications are some of the most commonly prescribed drugs in the United States. But while much is known about their general safety, the data are limited when it comes to pregnancy and breastfeeding.
Antilipemic agents are a pharmacologic class that contains 18 drugs. The class is divided into eight subclasses: bile acid sequestrants; fibric acid derivatives, HMG-CoA inhibitors; immunoglobulins; monoclonal antibodies; oligonucleotide inhibitors; vitamins; as well as two miscellaneous drugs, ezetimibe (Zetia) and lomitapide (Juxtapid). Another antilipemic – dextrothyroxine – has been removed from the market by the manufacturer.
Bile acid sequestrants
Bile acid sequestrants include cholestyramine (Prevalite, Questran), colesevelam (Welchol), and colestipol (Colestid). These drugs have the potential to cause fetal toxicity. This assessment is based on their mechanism of action. These agents are not absorbed systemically, or absorption is very poor and they bind bile acids into a nonabsorbable complex. This action can reduce intestinal absorption of fat-soluble vitamins A, D, E, and K.
Reports of fetal harm have not been located for the other two agents in this class, but there is only one case report involving five women for colesevelam and no reports for colestipol. Nevertheless, both of these drugs have the potential to cause fetal hemorrhage if they are taken for prolonged periods in pregnancy.
Fibric acid derivatives
The fibric acid derivatives subclass includes fenofibrate (Tricor, Lofibra) and gemfibrozil (Lopid).
Six reports, involving 13 pregnancies, have described the use of gemfibrozil during all phases of pregnancy. No teratogenic effects were observed in these cases. In one woman, similar concentrations of gemfibrozil and its active metabolite were found in the umbilical vein and artery at levels within the normal reference for adults.
There are seven HMG-CoA inhibitors, known as statins: atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), pitavastatin (Livalo), pravastatin (Pravachol), rosuvastatin (Crestor), and simvastatin (Zocor).
The interruption of cholesterol-lowering therapy during pregnancy should have no effect on the long-term treatment of hyperlipidemia. Moreover, cholesterol and products synthesized by cholesterol are important during fetal development as shown by the rise in maternal cholesterol levels during pregnancy. Although the potential for embryo-fetal harm has not been clearly documented, and that potential may eventually be confirmed as low, the use of these agents in the first trimester are best classified as contraindicated.
One consideration in estimating the embryo-fetal risk of statins is their classification as either lipophilic or hydrophilic. Three of the seven statins are hydrophilic (fluvastatin, pravastatin, and rosuvastatin); the remaining four agents are lipophilic. In a 2004 review of 70 reports, all adverse birth outcomes were reported following exposure to lipophilic statins (atorvastatin, lovastatin, or simvastatin) and none with the hydrophilic pravastatin. The authors stated that the findings were due to the fact that lipophilic agents equilibrate between maternal and embryonic compartments, whereas pravastatin is minimally present in the embryo.3 If this is indeed the case, and a statin must be used during pregnancy, fluvastatin, pravastatin, or rosuvastatin appears to be best.
Pravastatin also has been used for the prevention and treatment of preeclampsia.5,6 Although the teratogenic potential of these agents has not been fully determined, the risk for birth defects, if any, appears to be low even when exposure occurs during organogenesis.7,8,9 Nevertheless, avoiding these products during the first trimester appears to be best.