Trade names Hidrasec, Tiorfan, Zedott
Routes of administration By mouth Protein binding 90% (active metabolite thiorphan)
Metabolism Liver-mediated
Onset of action 30 min
Elimination half-life 3 hours
Excretion Urine (81.4%), feces (8%)
Racecadotril, also known as acetorphan, is an antidiarrheal medication which acts as a peripheral enkephalinase inhibitor.
Unlike other opioid medications used to treat diarrhea, which reduce intestinal motility, racecadotril has an antisecretory effect — it reduces the secretion of water and electrolytes into the intestine.
It is not available in the United States.
is used for the treatment of acute diarrhea in children and adults and has better tolerability than loperamide, as it causes less constipation and flatulence.
Racecadotril has no contraindications apart from known hypersensitivity to the substance.
There is insufficient data for the therapy of chronic diarrhea, for patients with renal or hepatic failure, and for children under three months.
Additional contraindications for the children’s formulation are hereditary fructose intolerance, glucose-galactose malabsorption and saccharase deficiency, as it contains sugar.
The most common adverse effect is headache, which occurs in 1–2% of patients.
Rashes occur in fewer than 1% of patients.
Other skin reactions include itching, urticaria, angioedema, erythema multiforme, and erythema nodosum.
No interactions in humans have been described.
Combining racecadotril with an ACE inhibitor can theoretically increase the risk for angioedema.
Racecadotril and its main metabolites neither inhibit nor induce the liver enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4.
Racecadotril has a low potential for pharmacokinetic interactions.
Enkephalins are peptides produced by the body that act on opioid receptors with preference for the δ subtype.
Activation of δ receptors inhibits the enzyme adenylyl cyclase, decreasing intracellular levels of the messenger molecule cAMP.
The active metabolite of racecadotril, thiorphan, inhibits enkephalinase enzymes in the intestinal epithelium.
This reduces diarrhea related hypersecretion in the small intestine without influencing basal secretion.
Racecadotril is rapidly absorbed after oral administration and reaches Cmax within 60 minutes.
Inhibition of enkephalinases starts 30 minutes after administration, reaches its maximum two hours after administration, and lasts for eight hours.
The elimination half-life, measured from enkephalinase inhibition, is three hours.