Olsalazine in pregnancy and breastfeeding


Risk Factor: CM
Class: Gastrointestinal agents/ Anti-inflammatory bowel disease agents

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary

Fetal Risk Summary

Olsalazine is used for the maintenance of remission of ulcerative colitis in patients who cannot tolerate sulfasalazine. It is poorly absorbed, approximately 2.4% after oral administration, with the remainder reaching the colon intact, where it is converted into two molecules of 5-aminosalicylic acid (mesalamine) by colonic bacteria (1). The history, pharmacology, and pharmacokinetics of mesalamine and olsalazine were extensively reviewed in a 1992 Reference (2).

Reproductive studies with olsalazine in rats have revealed reduced fetal weights, retarded ossifications, and immaturity of the fetal visceral organs with doses 520 times the recommended human dose on a weight basis (1). No reports describing adverse fetal effects following the use of olsalazine in human pregnancy have been located.

The use of 5-aminosalicylic acid, the active metabolite of olsalazine, in human pregnancy is discussed under Mesalamine (see Mesalamine).

Breast Feeding Summary

The active metabolite of olsalazine, 5-aminosalicylic acid (mesalamine), is excreted into human milk (see Mesalamine). In one study, however, only a metabolite of mesalamine, acetyl-5-aminosalicylic acid, was detected in human breast milk following the ingestion of olsalazine by a lactating woman (see Mesalamine) (3). Because diarrhea has occurred in a nursing infant of a mother receiving mesalamine (see Mesalamine), nursing infants of women being treated with olsalazine should be closely observed for changes in stool consistency.



  1. Product information. Dipentum. Pharmacia & Upjohn, 2000.
  2. Segars LW, Gales BJ. Mesalamine and olsalazine: 5-aminosalicylic acid agents for the treatment of inflammatory bowel disease. Clin Pharm 1992;11:51428.
  3. Miller LG, Hopkinson JM, Motil KJ, Corboy JE, Andersson S. Disposition of olsalazine and metabolites in breast milk. J Clin Pharmacol 1993;33:7036.

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