Brand Name: Neurontin

Available in 100 mg, 300 mg, and 400 mg capsules; 600 mg and 800 mg tablets; and oral solution (some products not appropriate for dogs)

Background

Gabapentin was originally approved to treat epilepsy in humans. However, gabapentin became more useful as a drug to control nerve pain.

More recently, the inhibitory (reducing brain activity) effects of gabapentin have been useful to control anxiety in animals, especially when being transported. Gabapentin is structurally similar to gamma amino butyric acid (GABA), an inhibitory neurotransmitter; neurotransmitters are chemicals that signal brain activity.

Originally, it was thought that gabapentin acted by acting like GABA, which reduces brain activity. However, gabapentin appears to accomplish most of its actions by changing the way calcium enters nerve cells. This mechanism is different than other drugs used to control seizures, pain, or anxiety, making gabapentin especially useful when it is combined with other drugs.

How this Medication is Used

Gabapentin is usually used to manage chronic pain, especially nerve-related pain. It is also used (primarily in cats) to relieve anxiety associated with veterinary procedures, travel, and other fear-generating situations. Gabapentin can also be used as an additional medication in seizure management. Dosing protocols are generally different depending on which use one is pursuing, with the anti-seizure doses tending to be higher and more frequent. 

Gabapentin may be given with or without food. If a dose is skipped, do not double up on the next dose; however, if you are unsure if a dose was accepted, the only consequence of dosing extra will likely be sedation and incoordination, manageable with confining your pet safely in their crate or pet-proof area of a room, etc.

Gabapentin's peak activity occurs approximately two hours after taking it by mouth.

Side Effects

Sedation and incoordination are the chief side effects of concern, though they are temporary and resolve in a few hours. Cats may also vomit or drool, but these side effects should resolve within 8 hours of receiving the medication. Diarrhea has also been reported.

Gabapentin can cause a false positive reading on urine dipstick tests for urinary protein.

Interactions with Other Drugs

For chronic pain relief, gabapentin is best started in combination with other pain relievers, but after a time, the other pain relievers can be discontinued, and gabapentin is effective as a sole agent. This may not be possible for conditions where the pain is progressively worse.

Oral antacids will hinder the absorption of gabapentin into the body by up to 20%, so it is important to separate the administration of these two medications by at least 2 hours.

Concurrent use of the narcotics hydrocodone or morphine with gabapentin can increase the effectiveness of gabapentin. Concurrent use of it with hydrocodone will decrease the effectiveness of the hydrocodone.

The sedation side effect is promoted by combining gabapentin with other sedating medications such as antihistamines, mirtazapine, CBD, or narcotic pain relievers.

Concerns and Cautions

Gabapentin may be given with or without food.

Doses for cats are small enough that a compounding pharmacy may need to prepare an appropriate product.

Gabapentin is removed from the body through the kidneys. If it is to be used in a patient with kidney insufficiency, the dose will need to be modified, or another product should be selected.

Gabapentin is not safe for use in pregnancy but should be safe for use in lactation.

Gabapentin should not be abruptly discontinued after long-term use as seizures can be precipitated. Instead, gabapentin should be gradually tapered off over a couple of weeks.

Many commercially prepared gabapentin oral liquids are sweetened with xylitol, which has toxic properties in the dog. The issue can be avoided by having liquid formulations compounded rather than using the commercially available oral liquid.