Animal studies did not show embryotoxicity or teratogenicity, except at maternotoxic doses. Human data are limited. Mesalamine crosses the placenta. Limited published human data show no increase in the overall rate of congenital malformations. Some data show an increased rate of preterm birth, stillbirth, and low birth weight; however, these adverse pregnancy outcomes are also associated with active inflammatory bowel disease. Blood disorders (leucopenia, thrombocytopenia, anemia) have been reported in newborns of mothers being treated with mesalamine. There has been one case report of renal failure in a newborn exposed during the third and fifth month of pregnancy. There are no controlled data in human pregnancy.

Non-steroidal anti-inflammatory drugs inhibit prostaglandin synthesis and, when given during the latter part of pregnancy, may cause closure of the fetal ductus arteriosus, fetal renal impairment, inhibition of platelet aggregation, and delay labor and birth. Continuous treatment with non-steroidal anti-inflammatory drugs during the last trimester of pregnancy should only be given on sound indications. During the last few days before expected birth, avoid agents with an inhibitory effect on prostaglandin synthesis.

Dibutyl phthalate (DBP) is an inactive ingredient in the US Asacol(R) and Asacol HD(R)'s enteric coating, and in animal studies maternal DBP was associated with external and skeletal malformations and adverse effects on the male reproductive system.

AU TGA pregnancy category C: Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.

US FDA pregnancy category B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Use is recommended only if clearly needed and the benefit outweighs the risk.

AU TGA pregnancy category: C
US FDA pregnancy category: B
Asacol(R) and Asacol HD(R) are US FDA category C

See references

Use with caution; benefit to mother should outweigh risk to the infant.

Excreted into human milk: Yes

Comments:
-If the infant develops diarrhea, discontinue breastfeeding.

Animal studies did not show adverse effects on the offspring during lactation. There is a case report of an infant with watery diarrhea that resolved when the mother stopped mesalamine, which reappeared with rechallenge.

Following oral administration of mesalamine, the milk to plasma ratio ranges from 0.1 to 0.3. The milk to plasma ratio of N-acetyl-5-aminosalicylic acid ranges from 5.1 to 16.5.

In published lactation studies, maternal mesalamine doses from various oral and rectal formulations and products ranged from 500 mg to 3 g daily. The concentrations of mesalamine and N-acetyl-5-aminosalicylic acid in milk ranged from nondetectable to 0.11 mg/L and 5 to 18.1 mg/L, respectively. Based on these concentrations, estimated infant daily doses for an exclusively breastfed infant are 0 to 0.017 mg/kg/day of mesalamine and 0.75 to 2.72 mg/kg/day of N-acetyl-5-aminosalicylic acid.

Dibutyl phthalate, an inactive ingredient in the enteric coating of Asacol(R) and Asacol(R) HD tablets, and its primary metabolite mono-butyl phthalate are excreted into human milk. The clinical significance has not been established.

See references