General FAQs About Treating FIP Using GS-441524 as posted by FIP Warriors using GS

July 22, 2019

These questions and answers about using GS-441524 come from the FaceBook page FIP Warriors using GS.  While this is a closed group, they welcome anyone who faces FIP and wants to explore the use of the only available source of GS-441524 today. While these drugs are unregulated by any governmental agency, they are proving effective at treating FIP

Q: What is GS?

A: GS is short for GS-441524 which is an experimental anti-viral drug (nucleoside analog) that has cured cats with FIP in field trials conducted at UC Davis but Dr. Neils Pedersen and his team. See study here.

It is currently available as an injection or an oral medication although the oral version is still not widely available yet. Please ask an admin!

Q: How long is the treatment?

A: Recommended treatment based on Dr. Pedersen’s original field trial is a minimum of 12 weeks of daily sub-cutaneous injections.

Bloodwork should be checked at the end of 12 weeks and cat’s symptoms should be assessed to see if additional treatment is needed.

Q: What is the correct dose of GS to give my kitty?

A: Dosing is based on the weight of the cat. The formula to calculate is: 4mg* (GS) x weight (kg) / GS concentration per 1mL** = dosage per 24hr.

*Neurological and Ocular FIP cats require 5mg/kg MINIMUM. Can go as high as 10mg/kg for extreme ocular or neurological cases.

**GS concentration per 1ml = total GS in bottle (mg) / total solution volume (mL)

Q: What exactly are “neuro” or “ocular” cases?

A: “Neuro” cat means that FIP has crossed the blood brain barrier and symptoms include central nervous system issues. Ataxia (weakness in my back legs especially), inability to jump fully without hesitation, lack of coordination and seizures may occur. Ocular involvement, which is common with the neurological form since the eyes and brain are closely connected, looks like this:

Q: How much does the 12 weeks of treatment cost?

A: Each 5 mL bottle of GS costs from $183 - $358 depending on the source. Dose will depend on the weight of the cat - each bottle of GS is 5mL liquid at either 15mg or 16.5 mg concentration depending on the brand purchased. Several brands offer both 12.5mg and 15mg but I believe almost all of us in the group are using 15mg or 16.5 mg versions. Use this to calculate dose: 4mg (concentration per 1 kg) x total kg of cat/15mg (concentration per 1ml) = daily dosage for 84 days.

12 weeks of treatment can cost anywhere from $1,700 - $11,000 USD depending on the brand of GS used and the weight of the cat.

Q: How do I buy GS?

A: We have access to agents for 3 different GS sellers in our group. All are located in China and all have shipped successfully to the US, Canada, Europe and Asia. The GS in China takes 7-10 days to arrive to the US after ordering and paying. Payment can be sent via Transfer Wise, PayPal or using a bank Wire Transfer. We try to help each other get started with a bottle or two while waiting for the package from China to arrive. Many of us keep extra bottles on hand specifically for these urgent situations.

Please direct message any of the admins of the group for help in connecting with the sellers or in getting GS quickly.

Q: How do I know the GS I am buying is the real thing and will work?

A: We have had the 3 brands that are being sold openly in our group tested at a reputable university lab for biological activity and acidity. All 3 appeared to be identical in bio-activity meaning they are all what they claim to be.

Q: With such big prices differences between tested GS brands, how do I decide which one to use?

A: The known differences - without prejudice - are the following:

  • Mutian II is $358 per 5mL bottle and is a 16.5mg/mL concentration They will guarantee that your cat will be cured if you use their GS as advised for the 12 week course. Should your cat relapse after the 12 weeks, they will provide free GS until the cat is cured. This GS is also less viscous than the other two tested brands.
  • Mark’s is $330 per 5mL bottle and is a 15mg/mL concentration. He offers a special deal if you buy 5 bottles at once, the 6th one is free. This brings the per bottle price down to $275.
  • Andy’s is $183 per 5mL bottle and is a 15mg/mL concentration. Currently in short supply in the US but can be ordered fm. China.


Q: What size syringes and needles do I need?

A: Depending on what your dose is, you can used either a 1 mL or a 3 mL syringe. Use a 20 gauge needle to draw up the GS into the syringe and then it’s best to CHANGE the needle to a fresh one of the same size so it isn’t dull from the draw. The GS liquid is some what thick and a larger needle allows it to be drawn up and injected faster. The LENGTH of needle can be anywhere from 1/2” to 1 1/2” in length. It’s a bit of a persona preference. Some use the longer needles to try and avoid any GS leaking out, some are more

comfortable injecting with a shorter needle.

Q: How do I give the GS injections?

A: The injections are given sub-cutaneously or “sub-cu” which means just under the skin. Injections are to be given every 24 hours at as close to the same time everyday as is possible for at least 12 weeks. The needle should NOT poke into the muscle of the cat. The GS stings upon injection but the pain is over as soon as the injection is over. There are several helpful videos that our members have posted showing how they inject and also many on YouTube. It’s best to have your vet do the first injection or two and to teach you how to do them. Kitties that are more difficult to restrain for the shots may require daily trips to the vet.

Q: What are the side effects of GS?

A: The only known side effects of GS are pain during injections and the possibility of skin lesions forming at the injection sites.

Q: What supplements do I give during GS treatment?

A: Many of our members use a variety of supplements during GS treatment to support organ and immune health. Dr. Pedersen believes that if you are using GS, you don’t need anything else so “save your money”. It’s a personal choice and below are some of what our community is using along with GS:

Q: Can I just buy the GS in powder form and mix it up myself?

A: You need some degree of expertise and the right equipment to prepare the diluent, adjust the pH, accurately weigh small amounts of drug, suspend- ing it in diluent, and fully solubilizing it by readjusting pH and sonication.

Some of the chemicals such as concentrated HCl are also dangerous in the hands of novices and technically the drug should be handled with gloved hands and with some care. People were having extremely difficult time doing these things and were continually asking advice, which is hard to give to ordinary people with no equipment. Therefore, it’s great that some Chinese were offering the drug already in solution, ready to inject. The only reason to buy the powder is if you can save a lot of money and have some- one that knows what they are doing prepare it for injection at little extra cost.

Q: Where do I get syringes and needles?

A: Hopefully your vet can start you out with a few syringes and needles. They can also be ordered on or Valley Vet Supply online but a prescription from your vet might be needed with VVS.

Q: How do I dispose of all of the used needles or “sharps”?

A: Here is a great resource for finding a sharps disposal location near you. You can also purchase something like this for about $4 at your local pharmacy and they might even take it for disposal when it’s full of sharps!

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