Acarexx (ivermectin)

Acarexx is a veterinary prescription otic solution containing ivermectin specifically formulated for the treatment of ear mite infestations in cats. Manufactured by Boehringer Ingelheim, Acarexx contains 0.01% ivermectin in a specialized vehicle designed for application directly into the ear canal. This medication provides a targeted approach to eliminating Otodectes cynotis, the common ear mite responsible for the vast majority of ear mite infestations in domestic cats. Ear mites are among the most prevalent parasites affecting cats, particularly kittens, shelter animals, and cats living in multi-cat environments, making effective treatments like Acarexx essential tools in feline veterinary medicine.

Ivermectin, the active ingredient in Acarexx, belongs to the macrocyclic lactone class of antiparasitic drugs. This medication works by binding to glutamate-gated chloride channels found in invertebrate nerve and muscle cells. When ivermectin binds to these channels, it causes an influx of chloride ions that hyperpolarizes the cell membranes, resulting in paralysis and death of the parasite. This mechanism of action is highly selective for invertebrates, as mammalian nerve cells use different chloride channel types, providing a favorable safety margin for use in cats. The targeted activity against ear mites makes Acarexx highly effective at eliminating these parasites from the ear canal while posing minimal risk to the feline patient when used as directed.

Acarexx is supplied as a ready-to-use otic solution in individual single-dose tubes, making administration convenient and ensuring proper dosing. Each tube contains 0.5 mL of the ivermectin solution, which is the appropriate dose for one ear of a cat. The single-dose packaging eliminates the need for measuring and reduces the risk of dosing errors. Treatment typically requires application to both ears, even if only one ear appears affected, as mites can be present in seemingly unaffected ears and can migrate between ears. The medication is designed for a single treatment application to each ear, with a repeat treatment recommended if ear mites persist after the initial treatment, typically evaluated two to four weeks later.

The safety profile of Acarexx has been established through clinical trials and extensive post-market experience. When used according to label directions in cats over four weeks of age, Acarexx is generally well-tolerated. Veterinary supervision is essential for proper diagnosis of ear mite infestation before treatment and to ensure the ear canal is healthy enough for medication application. Before prescribing Acarexx, veterinarians typically perform an otoscopic examination and may examine ear debris microscopically to confirm the presence of ear mites and rule out other conditions that could be causing similar symptoms. Following treatment, monitoring for resolution of clinical signs and follow-up examination ensures successful elimination of the parasites.

The primary and FDA-approved indication for Acarexx is the treatment of ear mite infestations caused by Otodectes cynotis in cats and kittens four weeks of age and older. Ear mites are microscopic parasites that live primarily within the ear canal, where they feed on tissue fluids and debris. These highly contagious parasites are responsible for approximately fifty percent or more of all ear infections in cats, making them one of the most common parasitic conditions in feline medicine. Cats with ear mites typically present with intense ear itching, dark brown to black ear discharge resembling coffee grounds, head shaking, ear scratching, and sometimes wounds around the ears from excessive scratching. Acarexx effectively eliminates these parasites, providing relief from these uncomfortable symptoms.

Ear mite infestations are particularly prevalent in certain cat populations, and Acarexx serves as an important treatment option for these groups. Kittens are especially susceptible to ear mites, often acquiring them from their mothers or littermates during the first weeks of life. Shelter cats and cats in rescue organizations frequently present with ear mite infestations due to the close contact between animals in these environments and the highly contagious nature of the parasites. Multi-cat households can experience ear mite outbreaks where the parasites spread from one cat to another. Outdoor cats and those with access to other animals are also at increased risk. For all these populations, prompt treatment with effective medications like Acarexx is essential for controlling infestations and preventing spread.

Beyond the ear canal, ear mites can occasionally be found on other areas of the body, particularly around the head, neck, and tail base where cats may spread mites during grooming or scratching. While Acarexx is specifically formulated for otic use, treatment of ear mite infestations helps reduce the overall mite burden on the cat. In cases where mites have spread beyond the ears, your veterinarian may recommend additional treatments or systemic antiparasitic medications to address mites on other body areas. Secondary bacterial or yeast infections that develop as a result of ear mite infestation may require additional treatment with appropriate antimicrobial medications.

Acarexx is selected for ear mite treatment based on several therapeutic advantages. The single-dose tube format provides convenient, accurate dosing without the need for measuring. The localized otic application delivers the medication directly to where mites reside, maximizing effectiveness against the parasites while minimizing systemic drug exposure. For cats that may not tolerate oral medications well or have conditions that preclude systemic ivermectin use, the topical ear application provides an alternative delivery route. The FDA approval specifically for cats ensures the product has been evaluated for safety and efficacy in feline patients, giving veterinarians and cat owners confidence in its use.

Veterinarians consider several factors when choosing Acarexx for ear mite treatment. The severity of infestation and presence of secondary infections influence treatment decisions, as cats with significant secondary bacterial or yeast infections may need combination therapy. The age and health status of the cat are evaluated to ensure Acarexx is appropriate. Compliance considerations matter, as the single-application treatment is often easier for owners to administer compared to multiple daily treatments over extended periods. Cost and availability also factor into treatment selection. In some cases, veterinarians may prefer systemic antiparasitic treatments that address both ear mites and other parasites simultaneously, particularly in cats with concurrent flea or intestinal parasite problems.

The dosing protocol for Acarexx is straightforward due to its single-dose tube presentation designed for feline patients. Each single-dose tube contains 0.5 mL of ivermectin otic solution, which represents the complete dose for one ear. For cats with ear mite infestations, the entire contents of one tube should be administered to each affected ear. Both ears should be treated even if only one ear appears clinically affected, as ear mites can be present in ears that do not yet show obvious signs of infestation and can migrate between ears. The product is approved for use in cats and kittens four weeks of age and older, and the same single-tube dose applies regardless of the cat's size or weight due to the local administration route.

The typical treatment regimen for Acarexx consists of a single treatment application to each ear, with veterinary evaluation recommended approximately two to four weeks after treatment. This evaluation determines whether the initial treatment was successful or if a second treatment is needed. In most cases, a single application effectively eliminates ear mites, but some infestations may require a second treatment to address mites that were in developmental stages less susceptible to ivermectin at the time of initial treatment. Your veterinarian will advise on the appropriate timing for follow-up and whether repeat treatment is necessary based on examination findings. Do not repeat treatment without veterinary guidance, as overuse of antiparasitic medications should be avoided.

The treatment duration consideration for ear mites differs from many other feline medications in that Acarexx is designed as a single-application treatment rather than a course of daily medications. However, the complete treatment timeline includes the waiting period before reassessment, typically two to four weeks. During this time, the medication continues to work and any remaining mites complete their life cycle. Clinical signs such as itching and discharge may take one to two weeks to fully resolve as the inflammation caused by the mite infestation subsides. If symptoms persist beyond this timeframe, contact your veterinarian for reevaluation, as this could indicate treatment failure, reinfestation, or an alternative diagnosis.

Proper administration technique maximizes the effectiveness of Acarexx treatment. Before application, gently clean visible debris from the outer ear using a cotton ball, but do not insert anything deep into the ear canal. Hold your cat securely, and if needed, wrap the cat in a towel for restraint. Twist off the tip of the single-dose tube to open it. Hold the ear flap gently upward and outward to straighten the ear canal. Insert the tube tip into the ear canal opening without forcing it deep inside, and squeeze the tube to empty its contents into the ear. After application, massage the base of the ear gently for about fifteen to twenty seconds to distribute the medication throughout the ear canal. Repeat with a new tube for the other ear. Your cat may shake its head after application, which is normal.

Because Acarexx is a single-dose treatment, missing a dose is not applicable in the traditional sense. However, if you are unable to complete treatment of both ears in one session, contact your veterinarian for guidance. If your cat is scheduled for a follow-up treatment and you cannot make the appointment, reschedule as soon as possible to ensure proper treatment completion. Do not attempt to stock up on or save Acarexx tubes for future use without veterinary guidance, as proper diagnosis should precede each treatment episode. Ear mite symptoms can resemble other ear conditions, and treating without proper diagnosis could delay appropriate care for non-mite conditions.

After Acarexx treatment, continuing follow-up care as directed by your veterinarian is important for ensuring treatment success. Attend the recommended recheck appointment to confirm mite elimination. Continue any additional treatments prescribed for secondary infections until completed as directed. In multi-cat households, all cats may need to be examined and treated to prevent reinfestation, even those not showing obvious symptoms. Environmental cleaning can help reduce recontamination risk, though ear mites survive only briefly away from hosts. Contact your veterinarian if symptoms do not improve within one to two weeks, if symptoms return after initial improvement, or if any concerning reactions occur following treatment.

Acarexx is generally well-tolerated by most cats when used according to label directions for the treatment of ear mite infestations. The otic route of administration delivers the medication directly to the ear canal, limiting systemic absorption and reducing the likelihood of body-wide adverse effects. Clinical trials conducted for FDA approval demonstrated a favorable safety profile in cats four weeks of age and older. However, as with any medication, individual cats may experience adverse reactions, and awareness of potential side effects enables cat owners to monitor their pets and seek veterinary attention when needed.

The most commonly observed side effects of Acarexx involve localized reactions within the treated ear. Some cats experience temporary discomfort or irritation at the application site, which may manifest as head shaking, ear scratching, or pawing at the ear shortly after medication administration. These local reactions are typically mild and transient, resolving within hours to a day after application. Mild redness within the ear canal may occur in some cats. In some cases, it may be difficult to distinguish medication-related irritation from the symptoms of the underlying ear mite infestation, which also causes itching and discomfort. If local symptoms worsen significantly or persist beyond a few days, consult your veterinarian.

Moderate systemic side effects, while uncommon with topical otic administration, can occur if significant amounts of ivermectin are absorbed or if the medication is used in ways other than directed. Signs of systemic ivermectin effects may include dilated pupils, drooling or hypersalivation, tremors, unsteadiness or difficulty walking, lethargy, and decreased appetite. These neurological effects relate to ivermectin's mechanism of action on nerve function. While these effects are rare with proper otic use of Acarexx, they may be more likely if the medication is ingested (such as through grooming after ear application), if excessive doses are applied, or in cats with compromised blood-brain barriers. If you observe any neurological symptoms after Acarexx administration, contact your veterinarian promptly.

Serious adverse reactions to Acarexx are rare but require immediate veterinary attention. Signs of severe allergic reaction include facial swelling, hives, difficulty breathing, or collapse. While ivermectin toxicity is more commonly associated with oral administration of higher concentrations, severe toxicity signs include profound neurological depression, ataxia progressing to an inability to walk, blindness, coma, and in extreme cases, death. These severe reactions are exceptionally rare with the low concentration otic product when used as directed. Certain cat populations may be at higher risk for ivermectin-related adverse effects, including young kittens under four weeks of age, debilitated or severely ill cats, and potentially cats with certain genetic sensitivities.

Unlike dogs, cats do not have the MDR1 gene mutation that causes ivermectin sensitivity in certain dog breeds such as Collies. However, individual sensitivity can occur in any cat, and rare adverse reactions should not be dismissed. Cats with compromised blood-brain barrier function due to illness, inflammation, or other factors may be more susceptible to neurological effects. Very young kittens may have increased sensitivity due to an incompletely developed blood-brain barrier. Long-term effects from single-dose Acarexx treatment are not expected, but monitoring your cat after treatment ensures any unexpected reactions are identified promptly. Report any adverse reactions to your veterinarian and to the medication manufacturer or FDA.

Acarexx should not be used in cats with known hypersensitivity or allergy to ivermectin or other avermectin-class compounds. Cats that have previously experienced adverse reactions to ivermectin, selamectin, moxidectin, milbemycin, or related macrocyclic lactone antiparasitics should not receive Acarexx without careful veterinary consideration of the risks and benefits. Cross-reactivity between compounds in this drug class can occur, so previous reactions to any related medication should be reported to your veterinarian. Allergic reactions can range from mild local reactions to severe systemic responses, and cats with a history of such reactions are at increased risk for similar responses with subsequent exposure.

Acarexx is not approved for use in kittens under four weeks of age, and this age restriction represents an important contraindication. Very young kittens have immature blood-brain barriers that may allow greater penetration of ivermectin into the central nervous system, potentially increasing the risk of neurological toxicity. Additionally, young kittens have immature liver and kidney function, which affects drug metabolism and elimination. Ear mite infestations are common in young kittens, often acquired from their mothers, but treatment should be delayed until kittens reach four weeks of age unless a veterinarian determines that the benefits of earlier treatment outweigh the risks in a specific case. Alternative treatments may be considered for very young kittens with severe infestations.

Certain medical conditions may contraindicate Acarexx use or require special caution. Cats with perforated or ruptured eardrums should not receive Acarexx, as medication penetration through a perforated tympanic membrane could lead to middle or inner ear exposure with potential for adverse effects. Because ear mites and severe ear infections can cause eardrum damage, veterinary examination to assess tympanic membrane integrity is important before treatment. Severely debilitated, ill, or underweight cats may have altered drug sensitivity and should be evaluated carefully before treatment. Cats with known neurological conditions should be treated with caution, as any additional neurological effects from medication would be concerning.

Pregnancy and lactation considerations apply to Acarexx use. The safety of Acarexx in pregnant cats has not been specifically established, and ivermectin is known to cross the placenta in other species. While systemic absorption from otic application is expected to be minimal, pregnant cats should only receive Acarexx if the veterinarian determines that the benefits outweigh potential risks. Similarly, nursing queens should be treated with caution, as ivermectin can be excreted in milk. Nursing kittens could potentially be exposed to the drug through their mother's milk, though exposure levels from otic treatment of the queen are expected to be very low. Discuss pregnancy or nursing status with your veterinarian before using Acarexx in breeding animals.

Informing your veterinarian about all medications, supplements, and treatments your cat is currently receiving is important before Acarexx administration. While drug interactions with topical otic Acarexx are less common than with systemically administered medications due to the limited absorption from ear application, potential interactions should still be considered. Complete disclosure of all current treatments, including other flea and parasite preventatives, prescription medications, over-the-counter products, and supplements, allows your veterinarian to evaluate any potential interaction concerns and provide the safest treatment plan for your cat.

The most significant potential drug interactions with ivermectin involve other medications that affect the central nervous system or that share metabolic pathways with ivermectin. Macrocyclic lactone antiparasitics, including other ivermectin products, selamectin, moxidectin, and milbemycin, share mechanisms of action with the ivermectin in Acarexx. Using multiple macrocyclic lactone products concurrently could theoretically increase the risk of adverse effects, though this is less concerning with otic application than with systemic products. If your cat is already receiving a systemic parasite preventive containing a macrocyclic lactone, inform your veterinarian before Acarexx treatment. Other drugs that affect GABA receptors or chloride channels, such as certain sedatives or anticonvulsants, could potentially have additive effects with absorbed ivermectin.

Ivermectin is metabolized by the liver, primarily through the cytochrome P450 enzyme system, and drugs that inhibit or induce these enzymes could theoretically affect ivermectin levels. Ketoconazole and other azole antifungals can inhibit cytochrome P450 enzymes and have been associated with increased ivermectin toxicity in some species when used concurrently. While this interaction is less relevant for the low-dose otic product, cats receiving systemic antifungal therapy should be treated with awareness of this potential interaction. Similarly, other drugs that inhibit P-glycoprotein, which helps prevent ivermectin from crossing the blood-brain barrier, could theoretically increase central nervous system exposure. Examples include cyclosporine, ketoconazole, and certain cardiovascular medications.

Concurrent use of other ear medications should be discussed with your veterinarian when Acarexx treatment is planned. Using multiple otic products simultaneously can affect medication distribution, absorption, and efficacy. Ear cleaning solutions should generally be applied before Acarexx and allowed to dry completely, or used at different times as directed by your veterinarian. If secondary bacterial or yeast infections require treatment alongside ear mite therapy, your veterinarian will advise on the appropriate timing and sequence of medications. Some combination otic products contain antiparasitic components and may provide alternative options to using Acarexx along with separate antimicrobial treatments. Always follow your veterinarian's specific instructions regarding the use of multiple ear products.

General precautions for Acarexx use emphasize the importance of proper veterinary diagnosis before treatment and appropriate handling during administration. Ear mite symptoms can overlap with other ear conditions including bacterial infections, yeast infections, allergies, and foreign bodies, making accurate diagnosis essential before treatment. Treating without proper diagnosis could delay appropriate care for conditions that do not respond to antiparasitic therapy. Acarexx should only be administered following veterinary examination confirming ear mite infestation. The medication is for otic use only and should not be taken orally, applied to other body areas, or used in species other than cats without specific veterinary direction.

While breed-specific sensitivities to ivermectin have not been documented in cats as they have in certain dog breeds, individual variation in drug response exists among all cats. Cats with unknown backgrounds or mixed heritage may have varying sensitivity to medications. Some Oriental breed cats have been anecdotally suggested to have heightened medication sensitivities, though this has not been specifically demonstrated for ivermectin. White cats or cats with certain genetic backgrounds could theoretically have different drug responses. Regardless of breed, all cats should be monitored after Acarexx application for any adverse reactions. First-time use of any macrocyclic lactone product in a cat warrants careful observation.

Environmental and handling precautions protect both the cat and the household during Acarexx administration. Wash hands thoroughly after handling the medication and applying it to your cat's ears. Avoid contact with your own eyes, skin, or mouth during application. If human exposure occurs, wash the affected area with soap and water; if eye exposure occurs, rinse thoroughly with water and consult a healthcare provider if irritation persists. Keep the medication out of reach of children and other pets. In multi-cat households, prevent grooming between cats immediately after application, as one cat grooming another's treated ears could result in oral ingestion of the medication.

Monitoring your cat after Acarexx treatment is important for assessing both treatment efficacy and safety. Observe for resolution of ear mite symptoms including decreased scratching, less head shaking, and improvement in ear discharge over one to two weeks following treatment. Watch for any adverse reactions, particularly in the hours immediately following application, including neurological symptoms (unsteadiness, drooling, tremors, dilated pupils), signs of allergic reaction, or severe local irritation. Keep your follow-up veterinary appointment to confirm successful treatment and determine if repeat application is needed. Contact your veterinarian if symptoms worsen, if new symptoms develop, or if improvement does not occur within the expected timeframe.

Special populations of cats require additional consideration when using Acarexx. Kittens between four and eight weeks of age represent the youngest approved population and should be monitored carefully after treatment. Geriatric cats may have age-related changes in drug processing and should be observed for any unusual responses. Cats with liver or kidney disease may have altered drug metabolism or elimination, though this is less concerning with topical otic application. Immunocompromised cats may have concurrent infections requiring additional treatment. Pregnant and nursing cats should only be treated when necessary and under veterinary supervision. Cats with any concurrent illness should be evaluated to ensure Acarexx treatment is appropriate alongside other health management needs.

Proper storage of Acarexx maintains the medication's stability and ensures effectiveness when used. Store Acarexx at controlled room temperature between 68°F and 77°F (20°C to 25°C), avoiding extremes of heat or cold that could degrade the product. Keep the medication in its original packaging until ready to use, as the packaging protects the single-dose tubes from light and environmental exposure. Do not use product that has been frozen or exposed to excessive heat. Check the expiration date on the packaging before use and do not use expired medication, as the potency and safety of expired products cannot be guaranteed. Store the medication in a location away from direct sunlight and moisture.

The single-dose tube format of Acarexx has specific handling considerations. Each tube is designed for one-time use in one ear and should be discarded after the contents are expelled, even if a small amount appears to remain. Do not attempt to save partially used tubes for later use, as the opened product may become contaminated or degrade. When opening the tube, twist off the tip carefully to create a clean opening for application. The tube tip should not be touched to contaminated surfaces before insertion into the ear canal. If multiple cats require treatment, use separate tubes for each cat and each ear to prevent cross-contamination. Inspect the packaging and tube before use and do not use if the packaging is damaged or the solution appears discolored or contains particles.

Safe handling and proper disposal of Acarexx protect your household, other animals, and the environment. Keep the medication in a secure location out of reach of children and pets when not in use, as accidental ingestion by children, cats, or other animals could result in adverse effects. Do not allow cats to groom each other immediately after application, as this could result in oral exposure to the other cat. Dispose of used tubes and packaging according to local guidelines for pharmaceutical waste. Do not flush unused medication or used tubes down the toilet. Many veterinary clinics and pharmacies participate in drug take-back programs that can accept unused medications for proper disposal. If such programs are not available in your area, consult your veterinarian or local waste management authority for appropriate disposal methods.

The majority of cat breeds tolerate Acarexx well, and breed-specific adverse reactions to ivermectin have not been documented in cats to the extent seen in certain dog breeds. Unlike Collies and related dog breeds that carry the MDR1 gene mutation causing severe ivermectin sensitivity, cats do not appear to have an equivalent common genetic susceptibility. This provides a favorable safety profile for ivermectin use across feline breeds. However, individual variation exists within all breeds, and any cat could potentially experience an unexpected reaction. Veterinarians approach ear mite treatment similarly across breeds while remaining alert to individual patient responses.

Certain breed characteristics may influence ear health and ear mite infestation patterns, though not necessarily Acarexx sensitivity. Scottish Fold cats have distinctive folded ear pinnae that do not affect the ear canal itself but may create a warmer, more enclosed environment around the ear opening. Persian and Himalayan cats with their brachycephalic conformation may have narrower ear canals. Devon Rex and Cornish Rex cats have larger ear openings relative to their head size. Breeds with abundant ear hair, such as Persians, may accumulate more debris that can harbor mites. While these anatomical variations affect ear care practices, they do not indicate altered sensitivity to Acarexx. Proper diagnosis and treatment remain appropriate for all breeds.

Size variation among cat breeds affects general dosing considerations, though Acarexx single-dose tubes are designed for cats across the normal size range. Large breed cats such as Maine Coons, Norwegian Forest Cats, and Ragdolls have proportionally larger ear canals, while smaller breeds and individual cats have smaller canals. The 0.5 mL volume in each Acarexx tube is appropriate for typical cat ear canals regardless of breed. Very small cats or kittens at the minimum approved age of four weeks should be monitored particularly carefully after application. Your veterinarian can advise if any adjustments to standard treatment protocols are appropriate for your individual cat based on size, breed, or other factors.

Age interacts with breed considerations in determining appropriate ear mite treatment. Purebred kittens are often at higher risk of ear mite infestation due to exposure in breeding environments where multiple cats are housed together. Shelter cats of any breed or mix frequently present with ear mites due to the contagious nature of the parasites. Senior cats of all breeds may have age-related changes that affect medication handling, though this is less relevant for topical otic products than systemic medications. Regardless of breed or age, all cats receiving Acarexx should be monitored after treatment for both efficacy and any adverse reactions. Follow-up veterinary care ensures treatment success and identifies any cats requiring additional intervention.

Several alternative medications are available for treating ear mite infestations in cats, providing options when Acarexx is not suitable or when different treatment approaches are preferred. Milbemite (milbemycin oxime) is another FDA-approved otic solution specifically for ear mites in cats, working through a similar mechanism as ivermectin. Revolution (selamectin) and Revolution Plus (selamectin and sarolaner) are topical spot-on treatments that address ear mites along with fleas, heartworms, and other parasites, providing broad-spectrum protection. Advantage Multi (imidacloprid and moxidectin) offers similar multi-parasite coverage. These systemic products may be preferred when concurrent parasite treatment is needed or when otic application is difficult.

Combination otic medications that treat both ear mites and secondary infections represent another therapeutic category. Tresaderm contains thiabendazole, which has activity against ear mites, along with neomycin for bacteria and dexamethasone for inflammation. While not a single-agent mite treatment like Acarexx, combination products address the common scenario of ear mite infestation with concurrent bacterial or yeast infection. Other combination otic products may be prescribed depending on the specific pathogens identified in your cat's ears. When ear mites are the only concern without secondary infection, single-agent products like Acarexx provide targeted treatment without unnecessary antimicrobial exposure.

Supportive care and environmental management complement ear mite treatment regardless of which medication is used. Gentle ear cleaning with veterinary-approved solutions can help remove debris and mite waste products, improving comfort and medication penetration. In multi-cat households, all cats should be evaluated and potentially treated to prevent reinfestation, as ear mites spread readily between animals in close contact. Environmental cleaning is less critical than with fleas since ear mites do not survive long off the host, but washing bedding and cleaning areas where cats sleep can reduce any environmental mite presence. Never substitute over-the-counter products or home remedies for veterinary-prescribed ear mite treatment without professional guidance, as inappropriate treatment can delay resolution and may cause harm. Your veterinarian can recommend the most appropriate treatment protocol based on your cat's specific situation and needs.