The US Food and Drug Administration (FDA) has approved lactitol (Pizensy, Braintree Laboratories), an osmotic laxative indicated for the treatment of chronic idiopathic constipation in adults. 

Lactitol is an off-white crystalline powder for oral solution. The recommended daily dosage is 20 grams (mixed with 4 to 8 ounces of water, juice, coffee, tea, or soda), preferably with meals. The dosage should be reduced to 10 grams daily in patients who have persistent loose stools. 

The approval was based on results of a 6-month placebo-controlled trial, a 3-month active-controlled trial, and a 1-year uncontrolled safety study. 

The primary efficacy analysis was based on the first 12 weeks of the 6-month treatment period among 594 patients, with 291 in the lactitol arm and 303 in the placebo arm. 

Significantly more patients using lactitol responded to treatment compared with placebo (25% vs 13%; 12% treatment difference; 95% confidence interval, 6.0% to 18.5%). 

The researchers defined responders as those patients who had at least three complete spontaneous bowel movements (CSBM) in a given week and an increase of at least one CSBM from baseline in the same week for at least 9 weeks out of the first 12-week treatment period and at least 3 of the last 4 weeks. 

In clinical testing, the most common adverse reactions were upper respiratory tract infections, flatulence, diarrhea, increased blood creatininephosphokinase, abdominal distension, and increased blood pressure. 

The label states that because of differences in clinical trial designs and settings, adverse reaction rates cannot be directly compared between trials or other drugs and may not reflect the rates observed in practice. 

Lactitol is contraindicated in patients with a known or suspected mechanical gastrointestinal obstruction or galactosemia. Hypersensitivity reactions, including rash and pruritus, have been reported during post-approval use of lactitol outside of the United States. 

Lactitol may reduce the absorption of oral medications administered at the same time. Therefore, oral medications should be administered at least 2 hours before or after lactitol dosing. 

The safety and effectiveness of lactitol have not been established in children. 

Complete prescribing information is available online.