This is a multi-center, open-label study evaluating pharmacokinetics of TRULANCE® (plecanatide) in breast milk of lactating women treated with TRULANCE

This is an open-label study in lactating women who have been prescribed TRULANCE® by their healthcare provider. The study will assess the pharmacokinetics of plecanatide and its active metabolite in breast milk of lactating women treated therapeutically with TRULANCE. Subjects will be screened prior to admission for Baseline assessments. Following final qualifications, the morning dose of TRULANCE will be administered under supervision from study personnel and serial samples of breast milk will be collected via breast pump.

Inclusion Criteria:

• Females ≥ 18 years of age
• Has been breastfeeding or actively pumping for at least 4 weeks
• Has been prescribed TRULANCE by a healthcare provider and has taken it for a minimum of 14 consecutive days before anticipated Baseline Visit
• Has the ability to understand and communicate the requirements of the study and is willing to continue breastfeeding or regular pumping in order to maintain milk supply for the duration of the study
• Weaning must not be underway

Exclusion Criteria:

• Has clinically significant medical or psychiatric condition (as determined by the Medical Monitor) other than the medical condition being treated with TRULANCE
• Has mastitis or other condition that would prevent the collection of milk from one or both breasts.
• Has participated in an investigational drug study within the 90 days prior to CRU admission

Lactating women with Chronic idiopathic Constipation (CIC) or Irritable Bowel Syndrome with Constipation (IBS-C)