Somatostatin Analogues May Ease Chronic Diarrhea in FAP Patients, Pilot Study Reports

Treatment with somatostatin analogues helps to ease the symptoms of difficult-to-treat diarrhea associated with familial amyloid polyneuropathy (FAP), a two-year pilot study suggests.

The medicines, however, were linked to severe though treatable side effects in three of the 14 patients. Larger and randomized trials are needed to confirm the efficacy and safety of the therapy, the researchers said.

These findings appear in the study “Somatostatin analogues for refractory diarrhoea in familial amyloid polyneuropathy,” published in the journal PLOS ONE.

Treatment-resistant, or refractory, diarrhea is a frequent and debilitating condition associated with FAP and can severely affect patients’ quality of life and ability to maintain good nutrition.

One of the difficulties for its management is that conventional anti-diarrhea treatments, including Imodium (loperamide), low fiber intake, and opioids often fail in FAP patients.

Somatostatin analogues are a class of drugs that mimic a naturally occurring hormone called somatostatin. These medicines work similarly to this hormone, slowing the  production of several other hormones, including many of those in the gut. They have been widely used for treating high blood pressure, neuroendocrine tumors and pancreatic fistulas, and have shown some efficacy in relieving intestinal motility disorders and refractory diarrhea. 

Researchers in France developed an observational pilot study to determine if somatostatin analogues could help ease symptoms of resistant diarrhea in FAP patients.

The study analyzed the outcomes of 14 patients with chronic refractory diarrhea, referred to the French national center for FAP patients, who had received somatostatin analogues as treatment. They were followed for two years.

Medicines included subcutaneous (under the skin) or intramuscular injections of slow release Sandostatin (octreotide), and subcutaneous injections of Somatuline Depot (lanreotide).

After three to six months on somatostatin analogues, nine out of 14 patients (64%) had a significant remission of diarrhea.

Treatment also led to a significantly reduction in daily bowel movements in all 14 patients, from a median of six to two per day; they also tended to ease symptoms of uncontrolled defecation, or fecal incontinence.

However, serious adverse events attributable to the medicines were observed in three patients (21%).

Two developed low blood sugar (hypoglycemia), with one person being hospitalized for treatment, and both stopped the analogues temporarily. A third patient, who had a pacemaker, developed an infection of the inner lining of the heart (endocarditis) believe to be related to injection-site bacteria after two years of treatment. Patients later resumed taking somatostatin analogues due to their anti-diarrhea benefits.

Blood-sugar drops are expected side effects of somatostatin analogues, which are known to trigger imbalances in blood-sugar levels, either raising them above (hyperglycemia) or lowering them below normal (hypoglycemia).

Impaired nutrition due to refractory diarrhea may also have contributed to hypoglycemia in the two patients, the team reported.

“[O]ur study, as the first of its kind, suggests that a drug class, somatostatin analogues, may relief symptoms of a rare and devastating disease, refractory diarrhoea associated with FAP,” the researchers wrote, adding that their efficacy and safety results should be confirmed in a prospective randomized trial.