Treatment of FIP: how to use GS441524 and Molnupiravir
Recommendations for injections, tablets and storage, plus an online daily dose calculator.
Treatment with injectable GS441524 or Molnupiravir
To give an injection to a cat, you must follow some strong recommendations.
- Subcutaneous only. The needle must not enter the muscle or stay within the skin. Drug that gets into the skin causes ulcers.
- Strictly on schedule. GS441524 — every 24 hours at the same time each day. Molnupiravir — twice a day, every 12 hours. Choose a convenient time: you will be injecting for a long while.
- With a helper. It is better if someone holds the cat. Have your veterinarian do the first few injections and teach you how to do them correctly.
- Do not dilute. GS441524 and Molnupiravir must not be diluted with water for injection or saline. Thanks to the well-adjusted solvent formulation of the “Vibe” brand, injections are less painful than similar drugs from other brands.
- Syringe and needle. A 2, 2.5, 3 or 5 ml syringe depending on the volume, and a 2.5 cm 23-gauge needle. After filling the syringe, change the needle to a new one — a clean needle keeps the drug out of the skin.
- Alternate sites. Do not inject in the same place for several days in a row. Pull the skin fold, insert the needle at least 2/3 of its length, make sure it is subcutaneous, and inject.
- After the injection. Pinch the skin fold with your fingers for 20 seconds to prevent leakage and contact with the skin. Treat the skin before and after the injection with Chlorhexidine.
Treatment with the tablet form of GS441524
Treatment with tablets is possible in the absence of gastrointestinal disease, diarrhea and vomiting, which may prevent adequate absorption of the drug. If your veterinarian has decided to treat with tablets, it is recommended to start therapy with injectable GS441524 “Vibe” for at least 2 weeks. Only after improvement of the general condition and positive dynamics can you switch to oral administration.
Tablets GS441524 “Vibe” must be given on an empty stomach for better absorption. Fix the cat’s head, open the lower jaw and put the tablet on the root of the tongue as deep as possible, then stroke the cat’s neck and she will swallow. If this is not possible, give the tablet with a treat or with food during feeding. Make sure the cat has swallowed the pill.
Duration of treatment and doses
In the treatment of FIP it is very important to prescribe an adequate dose of the antiviral drug, then monitor the cat’s weight and correct the dose as body weight increases. After the first 40 days of treatment an increase of the initial dose by 2 mg per kg is recommended. The duration depends on the form of FIP, the clinical condition and the cat’s response to therapy. The decision to complete treatment is made by the veterinarian based on the cat’s condition and laboratory results.
| Form of FIP | GS441524 (injections) | GS441524 (tablets) | Molnupiravir | Duration |
|---|---|---|---|---|
| Wet FIPno ocular or neuro | from 8 mg/kg, every 24 h | 10–12 mg/kg, every 24 h | 10–12 mg/kg, every 12 h | 84 days |
| Dry FIPno ocular or neuro | from 10 mg/kg, every 24 h | 12–14 mg/kg, every 24 h | 12–14 mg/kg, every 12 h | 84 days |
| Ocular formwet or dry | from 12 mg/kg, every 24 h | 14 mg/kg, every 24 h | 15 mg/kg, every 12 h | 84–140 days |
| Neurological FIPwet or dry | from 14 mg/kg, every 24 h | 16 mg/kg, every 24 h | 20 mg/kg, every 12 h | 112–180 days |
| Mixed formneuro + ocular | from 14 mg/kg, every 24 h | 16 mg/kg, every 24 h | 20 mg/kg, every 12 h | 112–180 days |
| Maximum dose | 30–50 mg/kg, every 24 h | 30–50 mg/kg, divided into two doses, every 12 h | 22 mg/kg, every 12 h | — |
Calculating the daily dose of injectable GS441524
cat weight (kg) × dose by form (mg/kg) ÷ concentration of the solution (mg/ml) = daily dose in millilitres
Example: a 1.9 kg cat with effusive FIP without ocular or neurological involvement is given 8 mg/kg per day. With a 30 mg/ml solution: 1.9 × 8 ÷ 30 = 0.506 ml, so 0.5 ml is drawn into the syringe.
Calculating the daily dose of GS441524 tablets
cat weight (kg) × dose by form (mg/kg) ÷ GS441524 content of one tablet (mg) = daily dose in tablets
Example: a 3.1 kg cat with dry FIP without ocular or neurological involvement may be given 13 mg/kg per day. With 40 mg tablets: 3.1 × 13 ÷ 40 = 1.0075 tablets — after rounding, 1 tablet per day.
GS441524 “Vibe” dose calculator
Minimum daily dose. Weigh your pet weekly and recalculate — the dose grows with body weight.
Injection formula: weight (kg) × dose (mg/kg) ÷ solution concentration (30 mg/ml) = ml per day. For tablets the dose is 2 mg/kg higher and the result is divided by the GS441524 content of one tablet. After the first 40 days of treatment the initial dose should be increased by 2 mg/kg.
The calculator is a guide. The final dose and course length are set by your veterinarian.
Molnupiravir dose calculator
Minimum single dose. Molnupiravir is given twice a day, every 12 hours.
Formula: weight (kg) × dose (mg/kg) ÷ 60 mg/ml ÷ 2 injections = ml per injection.
Molnupiravir is used when FIPV is resistant to GS441524. Prescribing decisions are made by a veterinarian.
Storage of GS441524 and Molnupiravir
- Unopened vials of GS441524 or Molnupiravir solution can be stored in a dark place at room temperature.
- GS441524 tablets must be stored in the refrigerator.
- For opened vials a refrigerator door is well suited, where the temperature is kept at +5 to +10 °C.
- Do not freeze. Shelf life of GS441524 and Molnupiravir is 3 years.
Why do veterinarians recommend GS441524 “Vibe” solution 30 mg/ml?
The “Vibe” brand produces injectable GS441524 at 30 mg/ml, unlike other brands that offer a lower concentration, which is more cost-effective for the manufacturer — 17 and 20 mg/ml have become industry standards of a sort. For us the priority is the maximum effectiveness of your pet’s treatment, less suffering for the cat during injections and a lighter financial burden on the owners.
Why is a higher concentration better than a lower one?
Injectable GS441524 is a highly acidic solution (pH 1.6–1.9): only in an acidic environment does the powdered substance dissolve completely and uniformly. Because of the high acidity cats experience significant pain during administration and skin irritation in the later stages of treatment. Sharp pain causes stress and, rarely, pain shock. In some cases ulcers, burns and areas of necrosis can be so severe that further injections become almost impossible until the skin is completely healed.
The 30 mg/ml concentration reduces the injection volume by 33% compared to 20 mg/ml and by 43.3% compared to 17 mg/ml. A smaller volume means significantly less skin damage, fewer ulcers and burns. For large cats (5 kg and above), which need high daily doses, 30 mg/ml has become the optimal choice.
To date, veterinary practitioners treating FIP have opted for the 30 mg/ml solution, which has proven to be the most effective in reducing treatment costs.