Introduction to Solensia™ Injection for Cats
SOLENSIA is a monoclonal antibody (mAb), also known as Frunevetmab Injection. This drug is primarily composed of the chemical Frunevetmab and is used to reduce pain associated with osteoarthritis (arthritis) in cats.
The U.S. Food and Drug Administration (FDA) approved SOLENSIA (Frunevetmab Injection) on January 13, 2022, for the treatment of osteoarthritis-related pain in cats. It is the first monoclonal antibody (mAb) approved for animals and used in the treatment of osteoarthritis.
A year later, on May 5, 2023, the FDA approved Zoetis’ Librela Injection (Bedinvetmab), which was launched on July 14, 2023. It became the first monoclonal antibody (mAb) approved for treating pain in dogs.
Both SOLENSIA (Frunevetmab Injection) and Librela (Bedinvetmab) are administered subcutaneously and function in a similar manner. They work by inhibiting the activity of a protein called Neuron Growth Factor (NGF), thereby acting as an Anti-Neuron Growth Factor (ANGF).

Mechanism and Effect of SOLENSIA Injection
SOLENSIA Injection contains Frunevetmab salt, a monoclonal antibody (mAb). This antibody is a type of protein that helps reduce pain caused by osteoarthritis or arthritis in cats.
Monoclonal antibodies (mAbs) identify and bind to Neuron Growth Factor (NGF) present in the body. NGF aids in the development and growth of nerve cells but also acts as a pain-enhancing factor during injury or inflammation.
When Frunevetmab binds to NGF, it prevents pain signals from reaching the brain, thereby reducing pain perception.
Solensia™ Injection Information
Approval Status | FDA Approved |
---|---|
Scientific Classification |
|
Drug Type | Veterinary Biologic |
Alternate Names | Frunevetmab Injection |
Origin | Developed by Zoetis Inc. |
Distribution |
|
Composition | Frunevetmab Protein-Based Solution |
Physical Traits |
|
Dosage & Administration |
|
Effectiveness |
|
Side Effects |
|
Population | Specifically for Cats (7+ Months Old) |
The Rajasthan Express: Solensia™ Injection Overview |
Significance of Librela and SOLENSIA
- Librela is the first monoclonal antibody (mAb) injection used for treating osteoarthritis or arthritis-related pain in dogs.
- SOLENSIA (Frunevetmab Injection) is the first approved treatment for osteoarthritis or arthritis-related pain in cats.
- Both drugs are developed by Zoetis Inc., a company known for pioneering new and effective veterinary medications.
SOLENSIA Drug Information
- Brand Name: SOLENSIA
- Chemical Name: Frunevetmab
SOLENSIA is the first monoclonal antibody (mAb) developed for use in animals. It is specifically designed to alleviate pain associated with osteoarthritis (arthritis) in cats. It is a protein-based drug.
Mechanism of Action: Frunevetmab monoclonal antibody (mAb) identifies and binds to the Neuron Growth Factor (NGF) protein, influencing its functionality.
What is Neuron Growth Factor (NGF)?
NGF aids in the development and growth of nerve cells. However, during injury or inflammation, it acts as an inflammatory mediator, increasing pain perception.
When Frunevetmab binds to NGF, it blocks pain signals from reaching the brain, providing relief from arthritis-related pain in cats.
Dosage Form and Administration
- Dosage Form: Injectable Solution
- Route of Administration: Subcutaneous (S/C) (under the skin)
Duration of Effect: SOLENSIA (Frunevetmab) Injection is administered once a month under the cat’s skin. The drug remains in the body for an extended period, and its effects become noticeable a few days after the first injection or once fully absorbed.
Since subcutaneous (S/C) administration results in slower absorption compared to other routes (such as intravenous (I/V), intramuscular (I/M), or intraperitoneal (I/P)), its effects appear gradually.
Additionally, administering irritating drugs via the S/C route can cause skin irritation due to the high nerve supply under the skin.
Advantages: This drug is effective and convenient for cats as it requires less frequent administration and provides long-lasting relief.
Other Important Information
- Approval Date: January 13, 2022
- Target Animals: Only cats (specifically developed to alleviate osteoarthritis-related pain in cats)
- Dosage: Administered subcutaneously once a month at a dose of 0.45 mg per pound (1 mg/kg) of body weight.
- Available Strength: 7 mg/ml
- Manufacturer: Zoetis Inc.
⚠ CAUTION This drug should only be administered by a licensed veterinarian or under their supervision.
Description of Solensia™ Injection
Solensia™ is a sterile injection containing 7 mg/mL of Frunevetmab. It is a specialized monoclonal antibody (mAb) that helps alleviate arthritis-related pain by inhibiting Nerve Growth Factor (NGF).
Composition: This solution is prepared in a histidine buffer and includes the following components:
- 10 mM L-histidine monohydrochloride
- 5% D-sorbitol
- 0.01% polysorbate 20
- Adjusted to pH 6.0 (using HCl/NaOH)
- Water for Injection (up to 1 mL)
Monoclonal Antibody Production :
Frunevetmab is an immunoglobulin G monoclonal antibody (mAb) specifically designed for cats. It is derived from mouse antibodies, where most parts are replaced with feline-compatible components, except for the complementarity-determining regions (CDRs). CDRs are identified using De Novo Protein Sequencing, a technique that utilizes mass spectrometry to analyze protein sequences and determine CDRs.
Mechanism of Action of Solensia™
- What is Frunevetmab?
- Frunevetmab is a felinized monoclonal antibody (mAb) that binds to and blocks NGF.
- It prevents NGF from attaching to TrkA and p75NTR receptors, reducing pain signal transduction.
- Laboratory tests confirm that Frunevetmab binds only to NGF and not to other neurotrophins like NT-3, NT-4, or BDNF.
- Role of NGF in Pain
- Osteoarthritic joints have elevated NGF levels.
- Injured or inflamed tissues release NGF and inflammatory cytokines.
- Cytokines are small proteins that act as immune system messengers and regulate inflammatory responses.
- NGF binds to TrkA and p75NTR receptors, increasing neurogenic inflammation and pain sensitivity.
- How Does Frunevetmab Reduce Pain?
- By binding to NGF, Frunevetmab inhibits TrkA/p75NTR signaling, reducing pain transmission.
- In vitro studies show that Frunevetmab effectively blocks NGF-induced nerve growth and cell development.
- It reduces pro-inflammatory elements that contribute to pain and inflammation.

Indication for Use of Solensia™
- Solensia™ is exclusively used for reducing osteoarthritis (OA)-related pain in cats.
- It is a monoclonal antibody (mAb) injection, also known as Frunevetmab Injection, intended for the treatment of OA pain in cats aged 7-8 months and older.
- Frunevetmab is administered subcutaneously in cats at a dosage of 0.45 mg/lb (1 mg/kg) based on body weight.
Why is this drug useful?
- Solensia™ is the first monoclonal antibody (mAb) specifically approved for treating OA pain in cats.
- Prior to Solensia™, no monoclonal antibody treatments were available for any animal species.
- Similarly, Librela (Bedinvetmab Injection) was launched in 2023 as the first OA pain treatment for dogs.
Function of Monoclonal Antibodies:
- Solensia™ contains a monoclonal antibody that binds to NGF, a protein essential for nerve cell growth.
- NGF also acts as an inflammatory mediator, enhancing pain perception during injuries.
- When the monoclonal antibody binds to NGF, it prevents pain signals from reaching the brain, providing relief.
Market Launch of Solensia™
- Solensia™ was introduced to the market in 2022 as a groundbreaking treatment for osteoarthritis and arthritis in cats. It offers an effective and safe alternative for feline OA management.
Osteoarthritis (OA):
Osteoarthritis, also known as OA, is a chronic and gradually progressing joint disease affecting dogs, cats, and large animals. It is more commonly observed in elderly animals. The condition involves the wearing down of cartilage between joints due to friction, causing pain while moving or urinating.
Joints contain a lubricating fluid called synovial fluid, which reduces friction between bones and maintains smooth joint movement. However, as animals age, the amount of synovial fluid decreases, leading to cartilage degradation and joint stiffness.
Treatment of Osteoarthritis (OA):
OA is generally considered a disease of elderly dogs and cats but can also occur in overweight animals or those with other orthopedic issues. It is a painful and progressive condition caused by cartilage deterioration. While OA has no cure, various treatments help alleviate pain in affected animals.
Treatment Options:
- NSAIDs (Non-Steroidal Anti-Inflammatory Drugs): Commonly used for pain relief, but prolonged use may lead to kidney and liver issues in dogs, cats, or other animals.
- Monoclonal Antibody Injections: Currently available options include Solensia™ for cats and Librela™ for dogs.
- Carprofen: An NSAID used to reduce inflammation and pain in OA treatment.
- Meloxicam: Another NSAID commonly prescribed for OA-related pain and inflammation in dogs.
New Osteoarthritis Treatment: Solensia™ Injection
Solensia™ is a recently introduced drug that is highly effective in treating OA in cats. It contains a monoclonal antibody (mAb) that binds to NGF, blocking pain signals from reaching the brain and providing relief.
This medication is specifically designed to manage OA-related pain and inflammation in cats aged seven months and older.
Symptoms of Osteoarthritis (OA): The severity of symptoms depends on the number of affected joints and disease progression. Common signs include:
- Joint pain and stiffness
- Limping while walking
- Difficulty climbing or jumping onto elevated surfaces
Dosage and Administration of Solensia™
- Dosage: Administered based on the cat’s body weight at 0.45 mg per pound (1 mg/kg).
- Route of Administration: Subcutaneous (S/C) injection, given once a month.
- Preservative-Free: The injection vial should be used entirely once opened. Any remaining solution should be discarded.
The Rajasthan Express: Solensia For Cats Dose Chart | ||||
Cat Weight (Pounds) | Cat Weight (Kilograms) | Injection Dose (mL) | Vial Count | Injection Dose (mg) |
---|---|---|---|---|
5.5 – 15.4 lb | 2.5 – 7 kg | 1 mL | 1 Vial | 7 mg |
15.5 – 30.8 lb | 7.1 – 14 kg | 2 mL | 2 Vials | 14 mg |
The Rajasthan Express: Solensia For Cats Dose Chart |
Contraindications for Solensia™
Hypersensitivity
- Solensia™ should not be administered to cats with hypersensitivity (allergy) to Frunevetmab.
Pregnant, Lactating, or Breeding Cats
- The use of Solensia™ injection is contraindicated in pregnant, lactating, or breeding cats, as it can cross the placental blood barrier and reach the fetus, potentially causing fetal abnormalities or death.
- Studies conducted on animals have shown that administration of anti-NGF monoclonal antibodies (mAbs) led to fetal malformations, an increase in stillbirth rates, and a rise in postnatal mortality.
Warnings About Solensia™ Injection
Not for Human Use
- Solensia™ injection is not intended for human use and should be kept out of reach of children.
Hypersensitivity (Allergic) Reactions
- Accidental self-injection may cause an allergic reaction, such as anaphylaxis. If a cat administered with Solensia™ exhibits an allergic response, immediate veterinary consultation is advised.
Use in Pregnant Cats
- Solensia™ injection should not be used in pregnant cats, as it is a monoclonal antibody capable of crossing the placental connection and reaching the fetus, potentially leading to fetal demise.
Effects on the Fetus
- NGF (Nerve Growth Factor) plays a crucial role in the normal development of the fetal nervous system. Studies involving anti-NGF antibodies in humans have demonstrated toxic effects on reproduction and development.
Precautions While Using Solensia™
It is very important to consider the age and health condition of cats when using Solensia (Frunevetmab) Injection, especially if the cat is already suffering from any illness. Consulting with a veterinarian before using this medication is essential. Additionally, it is important to ensure that the Solensia (Frunevetmab) Injection does not cause any adverse reactions when administered alongside other medications, such as NSAIDs (Carprofen, etc.).
There is currently limited detailed research available on the long-term use of this drug in cats and its effects in various specific circumstances. The information on the adverse effects of Solensia (Frunevetmab) and its use in other conditions is limited, as studies are still ongoing.
The drug should not be used without the advice of a veterinarian. A proper evaluation of the cat’s health condition and potential drug interactions should be conducted.
Hypersensitivity:
Side Effects:
The first use of Solensia (Frunevetmab) Injection or monoclonal antibodies may cause hypersensitivity and reactions such as anaphylaxis. In such cases, the following symptoms may be observed in cats:
- Itching
- Reddening of the skin
- Difficulty breathing
- Low blood pressure (Low B.P)
- Vomiting and diarrhea
- Dizziness
- Fainting
- Restlessness
- Seizures
Treatment:
- In such situations, immediately discontinue the medication and contact a veterinarian.
- Treatment can be administered using antihistamines and adrenaline (epinephrine).
- If the animal’s condition is critical, seek immediate emergency medical services.
Use with Other Antibodies:
Safety Not Evaluated:
- The safety of using this medication with other monoclonal antibodies has not been evaluated.
Reaction with Vaccines:
Study Unavailable:
- No studies have yet been conducted to determine how this monoclonal antibody reacts with other animal vaccines.
- It is necessary to consult with a veterinarian regarding the potential effects of vaccination and medication.
Formation of Antibodies:
Prevention:
- The use of Solensia (Frunevetmab) Injection or monoclonal antibody medications may lead to the formation of anti-frunevetmab antibodies in the cat’s body.
Effect of Reaction:
- After the formation of these antibodies, if monoclonal antibodies re-enter the body, the cat’s immune system may recognize it as an infection and react against it.
Impact:
- In this situation, the cat’s body attempts to reduce or eliminate the effects of the medication, which may diminish the effectiveness of the treatment.
Use with NSAIDs:
Safety Unknown:
- The use of Solensia (Frunevetmab) Injection with NSAIDs (Non-Steroidal Anti-Inflammatory Drugs), such as Carprofen, is not considered safe.
- Typically, NSAIDs like Carprofen are used for pain relief in osteoarthritis or arthritis.
- When used together, a mixed treatment of NSAIDs and Solensia (Frunevetmab) Injection may increase the risk instead of reducing the problem.
- Veterinarians are advised to avoid this combination.
Lessons from Human Studies:
- In humans, cases of rapidly progressive osteoarthritis (RPOA) have been observed in patients receiving a combination of NSAIDs and anti-NGF monoclonal antibodies. However, RPOA (reversible post-operative osteoarthritis) has not been reported or identified in dogs.
- No such response has been reported in cats yet.
Age Limit:
No Testing on Cats Younger than 7 Months:
- The safety of using Solensia (Frunevetmab) Injection in cats younger than 7 months or weighing less than 5.5 lbs has not been evaluated.
- Therefore, the use of this medication in young cats is advised against.
- It is essential to consult a veterinarian before use.
Knee Ligament Issues:
Not Included:
- Solensia (Frunevetmab) Injection has not been tested on cats that have had cruciate ligament (ACL) issues within the last 6 months.
- Cruciate ligament problems cause instability in the knee joint of dogs and cats, leading to lameness, pain, and arthritis-like conditions.
Long-Term Effects:
Unknown Effects:
- The adverse effects of using Solensia (Frunevetmab) Injection for more than 9 months have not been studied.
Heart Disease and NGF:
Long-Term Effects:
- The long-term effects of reducing NGF during heart disease in cats are unknown.
Effect of High Doses:
Changes:
High doses of Solensia (Frunevetmab) Injection in cats have been observed to reduce the size of neurons.
However, this effect was temporary and returned to normal once the medication was discontinued.
This phenomenon is associated with the use of high doses, so the medication should be administered strictly according to the prescribed dosage, and any unexpected effects should be discussed with a veterinarian.
Effects on Developing Kittens:
Caution:
NGF (Nerve Growth Factor) plays a critical role in the normal development of the somatic nervous system (SONS) and autonomic nervous system (ANS) in developing animals.
During the use of Solensia (Frunevetmab) Injection, young and growing kittens may face issues in the development of ANS and SONS as the drug may affect the developing nervous system.
Both the somatic nervous system (SONS) and autonomic nervous system (ANS) are part of the peripheral nervous system (PNS).
The somatic nervous system (SONS) controls voluntary activities such as muscle movements, while the autonomic nervous system (ANS) controls involuntary activities like heart rate and respiration. The ANS is divided into:
- Sympathetic Nervous System (SNS), which activates the body during stress or emergency situations.
- Parasympathetic Nervous System (PNS), which keeps the body in a relaxed state.
Caution:
Any disruption in the normal development of these systems could affect the physical functions of the kittens. Therefore, special care should be taken when using this medication in developing kittens.
Adverse Reactions for Solensia™
- Common Adverse Reactions Reported in Field Studies
A field study of 112 days was conducted to assess the effectiveness of Solensia™ injection in controlling pain associated with osteoarthritis in cats. A total of 275 cats participated in the study, with weights ranging from 2.5 to 11.4 kg and ages from 1.6 to 22.4 years. Among these, 182 cats were treated with Solensia™ and 93 cats received a control (vehicle) drug.
Some common adverse reactions reported in the study are as follows:
The Rajasthan Express: Adverse Reactions for Solensia™ | |||
Adverse Reaction | Solensia (N=182) (%) | Vehicle Control (N=93) (%) | |
---|---|---|---|
Vomiting | 24 (13.2%) | 10 (10.8%) | |
Injection site pain | 20 (10.9%) | 13 (14%) | |
Diarrhea | 12 (6.6%) | 5 (5.4%) | |
Abnormal behavior and behavioral disorders | 12 (6.6%) | 5 (5.4%) | |
Renal insufficiency | 12 (6.6%) | 4 (4.3%) | |
Anorexia | 12 (6.6%) | 4 (4.3%) | |
Lethargy | 11 (6.0%) | 3 (3.2%) | |
Dermatitis | 11 (6.0%) | 1 (1.1%) | |
Alopecia | 10 (5.5%) | 2 (2.2%) | |
Dehydration | 8 (4.4%) | 0 (0.0%) | |
Lameness | 8 (4.4%) | 2 (2.2%) | |
Pruritus | 7 (3.8%) | 0 (0.0%) | |
Weight loss | 6 (3.3%) | 5 (5.4%) | |
Scabbing on head/neck | 6 (3.3%) | 1 (1.1%) | |
Gingival disorder | 5 (2.7%) | 0 (0.0%) | |
Bacterial skin infection | 4 (2.2%) | 1 (1.1%) | |
Otitis externa | 4 (2.2%) | 0 (0.0%) | |
The Rajasthan Express: Adverse Reactions for Solensia™ |
2. Common adverse reactions reported in a 56-day field study :
Another 56-day control study was conducted to assess the safety of Solensia™ injection, which included 126 cats. Of these, 85 cats received Solensia™ (Frunevetmab injection), and 41 cats received vehicle control. The cats were given two injections at 28-day intervals.
The common adverse reactions reported in this study are as follows:
- Gastrointestinal issues such as vomiting and diarrhea.
- Skin-related issues, including dermatitis/eczema and hair loss (alopecia).
These skin issues were primarily caused by the acquisition activity monitor collar, which was necessary for the study and was worn by the cats around their necks.
Immunogenicity
All therapeutic proteins, including monoclonal antibodies (mAbs) used for the treatment of animals, can potentially induce immunogenicity in the body. This means that antibodies (anti-drug antibodies – ADA) may develop against these drugs, which can reduce the effectiveness of the monoclonal antibodies present in the Solensia™ injection. In other words, the body may recognize this monoclonal antibody as a foreign substance or antigen.
In a study of 259 cats, 4 cats receiving Solensia™ developed anti-drug antibodies (ADAs). One of these cats showed a positive antibody result, and this cat had a very low level of the medication, suggesting that the presence of ADAs might be impacting the drug’s effectiveness.
What to Do If Your Cat Experiences Side Effects from Solensia™?
1. Report Immediately:
If any side effects (adverse events) are observed during the use of Solensia™ (Frunevetmab Injection) in a cat, it is important to report them immediately to Zoetis and the FDA. This will allow for a thorough study of the side effect and facilitate finding an appropriate solution.
2. Report to Zoetis:
Zoetis is the manufacturer of Solensia.
Call Zoetis at 1-888-963-8471 to report the side effect.
Zoetis is required to report all side effects to the FDA.
3. Report Directly to the FDA:
Visit the official FDA website at www.fda.gov/reportanimalae to submit a side effect report.
4. Include the Following Information in the Report:
To make the report effective and accurate, include the following details:
- The cat’s complete medical history.
- How many times the cat has been administered the Solensia injection.
- The cat’s age and whether the pet had any pre-existing conditions.
- The lot number of the vial used.
This information will ensure that the side effect is properly studied and help reduce associated risks in the future.
Source By : Daily Med
Discover everything about Solensia for cats, including its uses, dosage, and potential side effects. Learn how this frunevetmab injection helps manage feline osteoarthritis pain.
THE RAJASTHAN EXPRESS
People Also Ask?
What is Solensia Injection?
Where is the Solensia Injection Administered in Cats?
What is the Success Rate of Solensia?
Does Solensia Work Immediately?
Is Solensia Safe?
- Vomiting
- Diarrhea
- Mild pain at the injection site
- Loss of appetite
- Lethargy
What is the Dosage of Solensia for Cats?
- Lighter cats (2.5–7 kg): 1 mL dose
- Heavier cats (7.1–14 kg): 2 mL dose