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FIP Treatment Made Easy with Oral Capsules

Updated: Mar 20, 2023

What is Feline Infectious Peritonitis (FIP)?

Feline infectious peritonitis (FIP) is a viral disease caused by feline coronavirus. It is a rare but fatal disease if left untreated. Until recently most FIP treatment using GS441524 anti viral has been done through subcutaneous injections, commonly referred to as the injection form, which can become extremely painful to cats after days of continued treatment. Injections become increasingly difficult to administer due pain caused by injection fatigue and skin sores. Many cat owners and veterinarians prefer the oral form of GS441524 antiviral drug for the treatment of FIP. Today, we will take a close look at oral version of GS441524, how it compares to the injection form, what are the advantages and disadvantages of each form, and when should we avoid using oral form.

2 treatment options for feline infectious peritonitis

There are two options for administering the antiviral nucleoside analog GS441524 to cats with FIP: subcutaneous injections or oral capsules/pills. Veterinarians typically prefer injections due to their precise dosing and rapid absorption, but cat owners tend to favor oral forms to spare their cats from the discomfort of injections. Cats can have adverse reactions to injections, such as developing an aversion or struggling during the procedure. Additionally, the acidity of the injectable form may cause injection site sores in some cats. In these cases, oral capsules or pills offer a suitable alternative to injections.

Giving GS-441524 oral medication
Giving GS-441524 oral medication

For several years, oral medication has been available for FIP treatment. However, veterinarians were initially hesitant to use GS441524 in oral form due to concerns about its bioavailability and absorption rate. However, in 2020, more cats with wet or dry FIP were successfully treated with oral GS441524, leading to a shift in sentiment among veterinarians. Initial concerns about possible drug resistance to oral administration, raised by UC Davis researchers, were proven unfounded as thousands of cats were successfully treated with oral GS441524, demonstrating its reliability in treating FIP.

How do oral capsules and pills differ from each other?

Although oral capsules and pills have similar effectiveness, capsules are more convenient to administer than pills. Capsules have a smooth coating that makes them easy to swallow and prevents any unpleasant taste from affecting the cat's taste buds. Once swallowed, cats cannot regurgitate capsules from the back of their tongue. Additionally, capsules can be administered in three ways.

  • by adding wet cat snacks on top of the capsules, in which case cats would eat the capsules whole.

  • by inserting capsules directly into the cat's mouth. Due to its smooth texture and absence of taste, cats readily swallow capsules without struggle.

  • by mixing the content of the capsule with normal cat food.

The downside of capsules is that they are more costly to manufacture. Thus, capsules are less preferred by manufacturers. is currently the only brand that offers oral GS in capsule form.

On the other hand, pills are a quicker and cheaper option to manufacture and were the first FIP treatment product to hit the market. Various brands such as Mutian, Aura/Spark, Capella, Lucky, Brava, and Kitty Care offer uncoated oral pills for FIP treatment. They are generally small in size and can be administered with ease in most cases. However, some cats may have difficulty swallowing due to their taste and texture, leading to regurgitation or even vomiting, causing an unpleasant experience for the cat and financial loss for the owner.

Although pills are easier and more affordable to produce, they often require inactive pharmaceutical ingredients called excipients to bind properly and prevent machinery from clogging. Unfortunately, pills can be regurgitated if not inserted deep enough into the throat or if the taste is unpleasant, and some cats can even spit them out after ingestion.

Muttian oral pills
Mutian oral tablets

When using oral GS treatment, it's important to consider the bioavailability of oral capsules. Unlike subcutaneous injections that directly enter the bloodstream, oral GS capsules and pills must pass through the digestive system before being absorbed. According to published research, healthy cats typically absorb between 40-60% of the supplied GS441524 orally. Therefore, a dosage greater than 10mg/kg is necessary in oral form to effectively treat neurological and ocular FIP. Researchers suggest that only in dosages exceeding 10mg/kg can GS441524 penetrate the blood-brain barrier and halt the replication of viruses that have reached the brain and nervous cells. In reality, most manufacturers provide a higher dose to avoid under-dosing and the risk of treatment regression and FIP relapses.

When is it appropriate to use oral GS for FIP treatment?

Although injections are the most direct and reliable method for treating FIP infections, it may be appropriate to use oral GS in certain cases. It is recommended to begin FIP treatments with injections and complete a minimum of 30 days before switching to oral medications. However, there are conditions where injections are preferred over oral GS for as long as the condition persists.

  • frequent vomit and diarrheas

  • liver and kidney complications

  • kittens

  • inherent poor immunity

  • inherent poor digestion and/or nutrition absorption

  • neurological and ocular symptoms

It is recommended to avoid oral GS treatment if your cat suffers from any of the conditions mentioned above. If your cat's condition noticeably regresses after taking oral medication for several days, you should consider increasing the dosage or switching to injections for the remaining days of FIP treatment.

Cost Comparison between Injection and oral GS-441524

The cost of oral GS varies significantly across brands, and each brand has its own unique method of calculating and administering dosage, leading to confusion. Additionally, the effectiveness of treatment can be impacted by the brand-specific dosing regimen. However, provides a simple oral GS dosing schedule compared to other brands, with GS capsules offered in three weight classes and a recommended daily dosage of one capsule based on the cat's weight class.

Although GS remains a black market product, the cost of both injections and oral pills has decreased considerably since their initial introduction several years ago. Currently, the price of oral GS treatment can range from a few hundred to several thousand dollars, depending on the brand and the weight of the cat.

Do oral FIP treatments cause a higher relapse rate?

According to FIP research, administering oral treatment for feline infectious peritonitis (FIP) at the appropriate time and dosage can be as effective as subcutaneous injections. However, FIP treatment experts generally agree that cats are more likely to experience relapse when treated orally compared to injections. Additionally, oral pills have shown to be less effective in treating cats with neurological and ocular forms of FIP, as well as digestive issues such as frequent vomiting and diarrhea. There are currently no known side effects from taking FIP oral meds.


Thanks to scientific breakthroughs made by research teams in the USA and manufacturers in China, the options for treating feline infectious peritonitis (FIP) have become more diverse and accessible. While injections are still considered the more reliable method of treatment, oral capsules and pills are now widely used and have shown success in treating FIP infections. It is important to use the oral form of GS441524 only under the appropriate conditions to avoid any potential relapse of symptoms in the future. The success of FIP treatment often relies on the experience and expertise of your veterinarian. If your veterinarian lacks experience in treating FIP, you can reach out to us for advice and guidance at

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