GS-441524
The development of FIP treatment with GS441524 was such that, since its discovery, it started with the use of an exclusively injectable form, to which a tablet form of the drug was later added. However, the existence of two forms using the same active substance brought a bit of confusion, which is related to the difference in absorption (biological availability - usability) of the active substance during injection and oral use. While almost 100% of the drug is used during injection, it is only about 50% for GS when administered orally. In order to be able to use the same dosage for both injectable and tablet forms of medicine, most manufacturers who produce both forms of medicine list the so-called equivalent GS content, which already takes into account the reduced availability of the drug administered orally. In this way, it is possible to easily switch from injections to tablets and vice versa. So, for example, if a tablet from the well-known manufacturers Lucky, Spark, or Hero etc... is equivalent (corresponding to the injectable form) let's say 16mg of GS, in fact it contains double the amount of GS, i.e. 32mg... But we can safely use 16mg in the calculation and follow the dosage recommendations for injectable use. However, due to the fact that many different manufacturers want to grab their piece of the GS pie on the market, many of them often state the real GS content for marketing reasons, because of course such a tablet looks financially more attractive than a tablet with the stated equivalent GS content... For such tablets but you really have to to know for sure from the manufacturer, what GS content it actually states, because if it states, for example, 40mg real content of GS in the tablet, when calculating the dose according to the generally valid recommendations for injections, you only have to use half tablet content… In other words, you use a 40mg GS tablet in your calculations as a 20mg tablet…
At this point, I would like to emphasize that GS-441524 is proven and safe by clinical studies and hundreds of thousands of cured cats worldwide, with minimal side effects, and is therefore used as a medicine first choice.
Recommended approximate dosage of GS-441524 at injection application or for tablets with the stated equivalent containing GS441524. The stated dosage applies to 1kg / 24h:
- 6 mg/kg q24h – Wet FIP
- 8 mg/kg q24h – Dry FIP
- 10 mg/kg q24h – Ocular FIP
- 12 mg/kg q24h – Neurological FIP
- 15 mg/kg q24h – Neurological relapse
Recommended approximate dosage of GS-441524 for tablets with the stated real containing GS441524. The stated dosage applies to 1kg / 24h:
- 12 mg/kg q24h – Wet FIP
- 16 mg/kg q24h – Dry FIP
- 20 mg/kg q24h – Ocular FIP
- 24 mg/kg q24h – Neurological FIP
- 30 mg/kg q24h – Neurological relapse
When you buy tablets yourself, pay extra attention to find out the information about whether the indicated content of the active substance in the tablet is real, or so-called. equivalent.
Note: Given that there is a reasonable assumption of an absorption limit of GS441524 in the digestive tract, it is recommended for dosages in equivalent 10mg/kg or more when taken orally, divide the dose into 2x a day.
MOLNUPIRAVIR (EIDD-2801)
In connection with the treatment of Covid-19, an antiviral called Molnupiravir appeared on the market, which is just a more comprehensible-sounding name for the substance labeled EIDD-2801. Unlike GS-441524, this antiviral is used exclusively in oral form. Even though its bioavailability (absorption capacity) in the digestive tract is similar to that of GS441524, i.e. around 50%, due to the absence of an injectable form, no "equivalent" content of the active substance is used in the recommended dosage by the manufacturers, and practically all state its real content. Thus, no conversion to 50% content is used. A 40mg tablet is simply 40mg, and this must also be taken into account when calculating the dose based on the recommended dosage. And there is one more very important thing... The pharmacokinetics of Molnupiravir is different from that of GS, and therefore Molnupiravir must be administered 2 times a day.
Recommended approximate dosage of EIDD-2801 tablets at 1kg / 12h:
- 6 mg/kg q12h – Moist FIP
- 8 mg/kg q12h – Dry FIP
- 10 mg/kg q12h – Ocular FIP
- 12 mg/kg q12h – Neurological FIP
- 15 mg/kg q12h – Neurological relapse
Although at first glance this dosage may seem the same as that of GS, do not forget the essential difference. This is a dosage of 12 hours (as opposed to 24 hours for GS441524).
Given that no official clinical trial has yet been conducted for the use of Molnupiravir in the treatment of FIP (one is currently underway at UC Davis), its use is recommended only in cases of apparent resistance to GS441524, thus Molnupiravir will find application mainly in severe neurological relapses. Keep in mind that the side effects of Molnupiravir are not yet accurately mapped and one of the most feared is the potential mutagenic effect leading to cancer. There is no need to panic, but it is necessary to realize that in the current state of knowledge it is better to use Molnupiravir only in cases where it is really necessary. Time will tell if the possible side effects are a real threat or will never be confirmed.
Legality vs. Illegality of treatment
An interesting paradox occurred in connection with the drugs GS441524 and Molnupiravir (EIDD-2801).
Efficacy and safety of GS441524 in the treatment of FIP was indeed confirmed clinical study, but due to the licensing policy of the patent owner (Gilead company) there is no legal the source of medicines and practically all production is concentrated in China.
On the other hand, the efficacy and safety of Molnupiravir in the treatment of FIP has not yet been confirmed no official clinical study, it exists but is legally available a form of medicine primarily intended for the treatment of Covid-19. In the Czech Republic/SR, it is distributed under the name Lagevrio in packs of 40 capsules, each containing 200 mg of the active ingredient, which is too much. Therefore, for use in cats, the drugs must be decapsulated. Of course, EIDD-2801 is already produced by several Chinese companies that also produce GS441524. Since the drug is not officially intended for the treatment of FIP, it is used off-label.
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