Diphenoxylate + Atropine

What is diphenoxylate + atropine?

Diphenoxylate + atropine (brand name: Lomotil®) is an opioid combination medication used to treat diarrhea or coughing in dogs and diarrhea in cats. Its use in cats is not generally recommended. Its use in dogs and cats is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is diphenoxylate + atropine given?

• Give diphenoxylate + atropine by mouth in the form of a tablet or liquid. Measure liquid forms carefully.
• Diphenoxylate + atropine may be given with or without food. 
• If vomiting occurs when dosed on an empty stomach, give future doses with food.

This medication should take effect within about 1 to 2 hours and improvement in clinical signs should follow.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. If it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Diphenoxylate + atropine may cause the following side effects: 

• Constipation
• Bloating
• Sleepiness

Serious adverse reactions may occur. If any of the following signs develop, stop giving diphenoxylate + atropine and contact your veterinarian immediately:

• Pancreatitis
• Vomiting
• Worsening diarrhea
• Appetite loss
• Extreme lethargy
• Jaundice: yellowing of skin, eyes, gums
• Hyperexcitability in cats
• Overdose may cause fever and high heart rate (tachycardia)

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment and notify your veterinarian if you have any concerns. Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting medication should stop working within 24 hours.

Are there any risk factors for this medication?

DO NOT USE diphenoxylate + atropine in:

• Pets that are allergic to either of the medications in the combination product
• Pets with diarrhea due to a toxin or an infection (e.g., parvovirus)
• Pets with liver failure
• Pets with obstructive jaundice
• Pets with intestinal obstruction

USE WITH CAUTION in:

• Cats
• Pets that are older or debilitated
• Pets with Addison’s disease (hypoadrenocorticism) or hypothyroidism
• Pets with liver disease or severe kidney failure
• Pets with respiratory disease
• Pets with central nervous system depression, such as head injury or hepatic encephalopathy
• Pets with acute abdominal conditions

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with diphenoxylate + atropine, including:

• Amantadine
• Amitriptyline (Elavil®) 
• Antihistamines
• Any medication that causes sedation, including phenobarbital, cannabidiol (CBD), and acepromazine
• Clomipramine (Clomicalm®)
• Monoamine oxidase inhibitors (MAOIs) like selegiline (Anipryl®), amitraz (Preventic®, Mitaban®)
• Promotility medications (e.g., metoclopramide, cisapride)

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any treatment.

Is any monitoring needed with this medication?

• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects. 
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian. 

How do I store diphenoxylate + atropine?

• Store this medication at room temperature, between 68°F and 77°F (20°C and 25°C).
• Protect from light.
• Keep out of reach of children and pets.

Diphenoxylate + atropine is a controlled substance, which means that it has been designated by the Drug Enforcement Administration (DEA) as having a potential for diversion to people other than the patient prescribed. Use of a controlled substance in any person or animal other than that for which it is prescribed is illegal. Therefore, this medication should be stored in a locked cabinet or safe that cannot be easily moved, with access limited to only those that need to administer the medication. Monitor the amount of medication remaining to ensure the expected amount is present.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.