Loperamide is an opioid-receptor agonist used mainly for its peripheral gastrointestinal effects. It reduces propulsive motility and has an antisecretory action, providing a symptomatic role in selected diarrheal disorders. Veterinary use is largely empirical and most often involves dogs. Transporter-mediated restriction of brain exposure contributes to its usual peripheral pharmacologic profile.
Loperamide activates mu-opioid receptors in the intestinal wall, reducing excitatory neurotransmitter release, propulsive contractions and secretory activity. Increased transit time and segmentation can enhance fluid and electrolyte absorption. P-glycoprotein normally limits central nervous system exposure, so the expected effect is predominantly intestinal. Longer intestinal residence and reduced secretion can produce firmer stools.
Do not use in: ABCB1-associated opioid sensitivity
Symptomatic diarrhoea
0.08 mg/kg
PO
Every 8 h
Up to 5 days; Do not use in: ABCB1-associated opioid sensitivity, Suspected invasive enteric infection; Short-term use; do not mask infection or ileus.
Symptomatic diarrhoea
0.1–0.2 mg/kg
PO
Every 8–12 h
Up to 5 days; Do not use in: ABCB1-associated opioid sensitivity, Suspected invasive enteric infection; Short-term use; do not mask infection or ileus.
Symptomatic diarrhoea
0.1 mg/kg
PO
Every 8 h
Up to 5 days; Do not use in: ABCB1-associated opioid sensitivity, Suspected invasive enteric infection; Short-term use; do not mask infection or ileus.
Symptomatic diarrhoea
0.08 mg/kg
PO
Every 6–8 h
Up to 5 days; Do not use in: ABCB1-associated opioid sensitivity, Suspected invasive enteric infection; Short-term use; do not mask infection or ileus.
Symptomatic diarrhoea
0.1–0.2 mg/kg
PO
Every 6–12 h
Up to 5 days; Do not use in: ABCB1-associated opioid sensitivity, Suspected invasive enteric infection; Short-term use; do not mask infection or ileus.
Chemotherapy-associated diarrhoea
0.08 mg/kg
PO
Every 8 h
Do not use in: ABCB1-associated opioid sensitivity
Cats
Use / stage
Dose
Route
Schedule
Instructions
Symptomatic diarrhoea
0.08–0.16 mg/kg
PO
Every 12 h
Symptomatic diarrhoea
0.04–0.06 mg/kg
PO
Every 12 h
Feline opioid antidiarrhoeal use is controversial; excitement may occur.
Rabbits
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Mice
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Rats
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Gerbils
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Hamsters
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Guinea pigs
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Chinchillas
Use / stage
Dose
Route
Schedule
Instructions
Staged diarrhoea treatment
Reference only
PO
0.1 mg/kg every 8 hours for 3 days, then once daily for 2 days; the staged schedule must remain explicit. The described dose is delivered in 1 mL water.
Avoid when decreased intestinal motility would be harmful.
Suspected enteric infection, obstructive/acute abdominal disease or hepatic encephalopathy requires particular caution; central excitation can occur in cats.
