OBJECTIVES: Assess patterns of utilization and costs of twice daily 24 mcg dosing of lubiprostone in a large managed care population.   METHODS: Patients included Humana members 18 years and older with medical claims for chronic constipation (CC) and/or irritable bowel syndrome (IBS) between April 1, 2006 and April 30, 2008. The index date was the first diagnosis of CC or IBS. Patients had at least 180-days of continuous enrollment pre-index and at least 30-days post-index. Users and non-users were compared.  Users were compared pre- and post-lubiprostone initiation. RESULTS: A total of 92,804 patients with a diagnosis of CC or IBS were identified during the study period; 1873 filled at least one 30-day prescription for lubiprostone. Seventy-five percent of users were female. Lubiprostone users were younger than non-users (61.6 vs. 66.2 yrs old) and more likely to be co-prescribed opiates (35.5 vs. 29.4%), antihistamines (14.8 vs. 9.5%) and tricyclic antidepressants (8.1 vs. 4.7%), all statistically significant. Common co-morbidities in lubiprostone users were back problems (23.6%) and abdominal pain (21.9%). A total of 1605 users had both 6-months pre- and post-lubiprostone initiation data. A total of 42.2% of these patients filled more than one 30-day lubiprostone prescription; 6.42% filled 6 or more. Usage of other prescription laxatives decreased by 4.6% (p<0.05) subsequent to lubiprostone initiation. Monthly health care costs per utilizing member increased by $67.10 (p<0.0001). Pharmacy costs rose by $71.73 (p<0.0001) and ER costs decreased by $8.12 (p<0.05). Pre-post changes in outpatient and inpatient costs were not significant. Monthly inpatient and ER visits for these 1605 members decreased by 0.31 and 0.08 per utilizing member respectively (p<0.05) in the 6-months after starting lubiprostone. Changes in outpatient visits were not significant. CONCLUSIONS: Lubiprostone users were younger females who were co-prescribed opiates and had back problems. Higher health care costs were offset by a decrease in ER costs.