GS Brands

Updated 9/5/2022

On this page, I will explain what is in a bottle of injection-type GS and mention a few of the popular brands. In principle, they should all be the same but there are differences. The baseline mixture is defined in the UC Davis paper:

“GS-441524 was provided by Gilead Sciences as a pure and highly stable powder and diluted to a concentration of 10 or 15 mg/ml in 5% ethanol, 30% propylene glycol, 45% PEG 400, 20% water (pH 1.5 with HCI). The mixture was placed in sterile 50 ml glass injection bottles, agitated until in suspension, and then placed in a sonicated water bath for 5–20 mins until clear.”

However, we have no way to verify that the different brands follow this exact formulation. We have seen differences in thickness “viscosity) and I have personally measured the acid level (pH) of most of the major brands. I measured the UC Davis mixture to have a pH of 2.1 and most of the leading brands currently available have a pH of 1.8 to 1.9 (slightly more acidic) than the UC Davis mix. You can see that HCl (hydrochloric acid) is a necessary ingredient. One reason for this is that GS powder will not dissolve in pure water. The solubility increases as the acid concentration increases (lower pH). While this may sound bad, HCl is very common in the pharmaceutical world. Many drugs are supplied in the HCl or hydrochloride form.

Until recently, we had no no way of knowing anything about actual vs claimed concentration or purity. As of July 2020, we have tested a number of the current brands and some of the no longer available brands. The detail are discussed on the Testing page. Some of the results are surprising. We will repeat here what we say on the testing page. The Test results should never be the sole basis for choosing a GS brand. Much higher weight should be assigned to extensive clinical testing.

Until recently, the brands I was comfortable recommending were only the ones considered to be “Tier 1” by the Hong Kong FIP group This “tier” system has not been updated in a number of months. Brands that I can recommended are the ones that I have seen wide-spread, effective use here in USA and in some cases have been independently tested for concentration and purity. Note that none of the brands are officially approved anywhere in the world and we have no way of knowing that brand quality stays consistent. Nevertheless, theses are brands I would be willing to use on my own cat if needed.

Trusted brands

Capella: Capella makes both injection and pill forms of GS. It has been available since February 2020 and was rated Tier 1 in HK since May 2020. It is used in countries all over the world and could well be the most popular brand. Capella injection is supplied in 6ml bottles, has rated concentration of 15mg/ml, and contains 90 mg of GS per bottles. Capella is the brand that new brands try to undercut.

Capella Pills: Capella makes two sizes of pills, a 1kg pill and a 2kg pill. For FIP cases without Ocular or neurological symptoms, you would give one 1kg pill per day per 1kg of cat weight or one 2kg pill per 2kg of cat weight. Round up to nearest half pill. Multiply the number of pills per day by 1.5 for ocular or by 2 for neurological forms.

Snowy: Snowy is a relatively new brand but has been in widespread use for most of 2022. Technically it is not HK Tier1 because it is not being distributed in HK. However, we know the maker and can vouch for it’s Tier 1 quality. It is the least expensive, fully vetted brand with Tier 1 quality. Snowy currently comes in 5.2ml bottles. We use 15mg/ml for the concentration in the calculators but we know the actual concentration is higher.

Spark/Aura: Spark was at one time rated a Tier1 brand but had sporadic shipping problems in early 2020. They now have several versions of their injection form and also pills. See my Facebook Groups page for a link to Spark Group where you can get more information. The Spark injection and pills are available for direct order from their website.

Lucky is another brand which is available in some groups and also through a website. Its price point is similar to Capella . Lucky comes in a 15mg/ml version and a “high concentration” 20mg/ml version.

Note that high concentration versions typically require more acid (lower pH) to keep the extra GS in solution. Your shot volume will be smaller but the injection may sting more.

Oscar: Oscar became available in mid-2021 and was elevated to Tier 1 status in September 2021. Oscar comes in 5ml bottles, is 15 mg/ml and contain 75 mg of GS per bottle. Oscar may be a little less expensive than Capella but has less GS per bottle so be sure to compare the actual $/mg for each. I have not heard much about Oscar recently.

Brava: Brava does not seem to be available in USA anymore

Brands I am aware of but don’t recommend

Mutian: The sister and brother behind Mutian were arrested in China in 2021 and sentenced in 2023 to prison in China for 15 and 8 years respectively. Brands like Freecat, Bliss and proline were apparently attempts by some of Mutian people that were not arrested to continue business. ’nuff said.

Panda, Ruby, Atlas, Hero, Cotton, Pine, Miner, Slayer, Kitty Care, HuaHua, Tian Xing. These are brands that I have seen supplied by some in the USA. Some are identical with the different names. None are considered Tier 1 by the HK group. Some like Freecat have done more harm than good. Panda has no independent testing (that I am aware) and may be a decent brand but they have plagiarized FIP Warriors by calling their FB group “FIP Warriors USA”. Many people are confused by this.

My position on Oral forms of GS

New position on GS pills: Consider switching to pills after doing injections for “a while” and seeing your cats condition and blood work improve. At this time, I can recommend Capella, Brava, or Spark pills from the various pills out there.

Previous position on GS pills: As you read about treating FIP with GS-441524, you may see that there are oral forms of GS available. With oral forms, you give your cat pills or capsules instead of injections. This may seem appealing at first glance because giving shots sounds harder than giving pills. However, injection is the most reliable method of giving GS and here is why. The only published clinical trail regarding GS is the UC Davis paper and they only studied injection-type GS treatment. While they mentioned oral form should be possible, no one has published an actual clinical trial with any of oral GS products. While oral forms of GS have apparently worked on some cats, Dr. Pedersen has stated that absorption of any oral medication will vary from cat to cat. So pills can be expected to work better with some cats than others. Some cats are easy to pill and some very difficult. You won’t have injection pain but you may have diarrhea or vomiting. Some cats may back-slide or relapse due to poor absorption. In the case of Mutian’s product, they claim that the active ingredient in their capsules is not GS-441524 but rather what they call Mutian X. Based on that claim, Mutian feels that the Gilead patent does not apply to their product. If this is true, then the UC Davis paper about efficacy would also not apply. I feel strongly that GS treatment by injection has the highest probability of curing your cat’s FIP and is the only treatment method backed by published research. All that said, if you decide you want to treat with one of the oral forms of GS, I will do my to help you locate a reputable oral form.