CaliciX™ – Antiviral Therapy for Feline Calicivirus Stomatitis

CaliciX™ – EIDD-1931 Oral Capsules (15 mg)

Antiviral agent for feline calicivirus–associated stomatitis and oral inflammatory disease

For veterinary use only

Active Ingredient

• EIDD-1931 (β-D-N4-hydroxycytidine) – 15 mg per capsule
• Pharmacologically equivalent to >60 mg molnupiravir (EIDD-2801)

Indications
CaliciX™ is intended for the management of severe oral inflammatory diseases driven by chronic or high-load FCV infection, including:

Primary Indications

• Feline Chronic Gingivostomatitis (FCGS)– particularly cases with confirmed or suspected calicivirus involvement
• Juvenile Onset Gingivitis/Stomatitis
• Caudal Stomatitis
• Ulcerative Stomatitis
• Viral Glossitis & Lingual Ulceration
• Buccal, Labial & Palatal Ulcers of Viral Origin

Clinical Signs

• Oral pain, reluctance to eat
• Ptyalism (drooling)
• Halitosis
• Dysphagia
• Mucosal ulceration
• Gingival bleeding
• Weight loss / poor body condition due to oral discomfort

CaliciX™ may be used as primary antiviral therapy or as part of a multimodal treatment plan (e.g., analgesia, dental care, antibiotics for secondary infection).

Mechanism of Action
EIDD-1931 is the active intracellular metabolite of molnupiravir.

Once absorbed, it is phosphorylated to its triphosphate form and incorporated into viral RNA by RNA-dependent RNA polymerase (RdRp), causing:

• Lethal mutagenesis
• Rapid decline in viral replication
• Reduced viral load within mucosal tissues

Compared with EIDD-2801, CaliciX's EIDD-1931 demonstrates:

• Higher intrinsic antiviral potency
• More predictable pharmacokinetics
• No requirement for enzymatic conversion from prodrug form

Reference potency data shows EIDD-1931 is 4.4x - 10× more potent than molnupiravir.  

Reference: ht​​​tps://pmc.ncbi.nlm.nih.gov/articles/PMC9227765/

Treatment Duration:
4–12 weeks depending on lesion severity, clinical response, and relapse risk.

Combination therapy:

Often paired with:

• Analgesics (e.g., meloxicam)
• Doxycycline for secondary bacterial overgrowth
• Chlorhexidine oral care
• Nutritional support / appetite stimulants

Pharmacokinetics

• High oral bioavailability in felines
• Rapid intracellular activation
• Excellent distribution into oral mucosa, gingival tissues, and saliva
• Stable therapeutic levels with BID dosing
• Lower mg/kg requirement due to high potency
• Safety Profile

Contraindications:

1. Pregnant or breeding cats (theoretical mutagenicity risk)
2. Severe hepatic impairment
3. Caution in renal insufficiency if combined with NSAIDs

Monitoring:
For extended therapy (>6 weeks):

• CBC every 2–4 weeks
• ALT/AST if concurrent medications used
• Body weight and pain scoring

Adverse effects are typically mild and dose-dependent (GI upset, transient lethargy).

Clinical Expectations
Veterinarians may expect improvement in:

1. Drooling and oral pain within 3–7 days
2. Ulcer depth reduction within 1–2 weeks
3. Appetite return and weight gain within 2–3 weeks
4. Mucosal healing and inflammation reduction over 4–12 weeks

Best outcomes are seen when FCV involvement is confirmed or strongly suspected.

All orders are processed and dispatched within 24 hours using secure, tamper-evident, and discreet packaging to safeguard product integrity during transit.

We offer fast domestic and international delivery to most destinations across the Europe, GCC, Asia, North America, and South America, with typical delivery times of 2–5 business days.

For destinations that require international shipping, shipments are handled by DHL and FedEx for maximum reliability and tracking accuracy.

Domestic deliveries are fulfilled through trusted local express couriers to ensure prompt arrival.

Mild Cases (early ulcers, juvenile gingivitis, mild viral mouth irritation) to Moderate Cases (gingivostomatitis with eating discomfort, drooling, moderate ulceration): Use CaliciX™

Severe Cases (FCGS, caudal stomatitis, extensive ulceration, severe pain, anorexia): Use CaliciX™ Max

Dosage Instruction:

Below 2.5kg, 1 capsules every 12 hours

2.5 kg ~ 5 kg, 2 capsules every 12 hours

Above 5 kg, 3 capsules every 12 hours

Example 1: Luna weighs 4.5kg, has juvenile gingivitis, with bright red gums.  Use CaliciX™, 2 capsules, ever 12 hours.
Example 2: Spark weights 3.3kg, has stomatitis, and is experience moderate to severe pain.  Use CaliciX™ Max, 2 capsules, ever 12 hours.

Each CaliciX™ capsule contains 15 mg EIDD-1931.

Each CaliciX™ Max capsule contains 30 mg EIDD-1931.

If vomiting occurs within 30 minutes, administer another full dose.

Treatment Duration: 

• Mild: 4–6 weeks
• Moderate: 6–8 weeks
• Severe FCGS: 8–12+ weeks

Adjust dose based on clinical signs
Signs of under-dosing:

• Persistent drooling
• Pain on chewing
• Slow ulcer healing
• Weight loss

Increase dosage within recommended band only under veterinary direction.

Storage: Store in a dry, cool place away from sunlight.

Packaging: 
60 capsules packed in a vacuum-sealed mylar bag.

Expiration: 12 months from production date printed on the package.

Relapse is Possible – Plan for Maintenance

Even with successful initial treatment, 20-30% of cats experience relapses.

Why relapses happen:

• FCV can persist in tissues even after viral suppression
• Stress, illness, or immune system changes can trigger reactivation
• Some cats are genetically prone to chronic FCV

Maintenance strategies to prevent relapse:

Option A: Continuous Low-Dose

• After 12-16 weeks at full dose, reduce to half of previous dosage.
• Continue indefinitely
• Most cost-effective for cats with frequent relapses

Option B: Intermittent Courses

• Stop after 12-16 weeks
• Monitor closely
• At first sign of relapse (mild drooling, reduced appetite), restart 4-6 week course
• Some cats do well with this approach (2-3 courses per year)

Option C: Seasonal/Stress-Triggered

• Some cats relapse during specific triggers (boarding, moving, new pets, illness)
• Use CaliciX™ Max preventively during high-stress periods

Early relapse warning signs:

• Increased drooling (even if mild)
• Slight decrease in appetite
• Pawing at mouth occasionally
• Bad breath returning
• Gum redness reappearing

Act quickly: Restart treatment at first signs = easier to control than waiting until severe relapse.

CaliciX™ can generally be used alongside other medications, but be aware:

✅ Safe to combine:

• Antibiotics (amoxicillin, clindamycin, azithromycin)
• Pain medications (gabapentin)
• Appetite stimulants (mirtazapine, maropitant)
• Vitamin B12
• Probiotics
• Most chronic disease medications (thyroid, blood pressure)

⚠️ Use with caution (vet supervision required):

• NSAIDs (meloxicam, robenacoxib) – monitor kidney function closely
• Steroids (prednisolone, dexamethasone) – can use short-term, but taper as CaliciX™ works
• Chemotherapy drugs – potential additive bone marrow suppression
• Immunosuppressants (cyclosporine) – may reduce effectiveness of immune response needed to clear virus

❌ Avoid:

• Ribavirin (another antiviral) – redundant mechanism, increased toxicity risk
• Other experimental antivirals without vet guidance

If your cat is on multiple medications, provide complete list during consultation.

⚠️ EIDD-1931 has potential teratogenic effects (can harm developing kittens).

Absolutely do NOT use in:

• Pregnant queens (any stage of pregnancy)
• Nursing queens (drug may pass into milk)
• Breeding cats attempting to conceive

If your cat is:

• Female and not spayed → spay before starting treatment or ensure no breeding exposure
• Already pregnant → do not use CaliciX™ Max, discuss alternatives with vet
• Nursing → wait until kittens are weaned (8-10 weeks)

Male cats:

• Limited data on effects on sperm/fertility
• Use with caution in breeding males
• Consider temporary contraception if female cats in household