Selamectin

Description

Selamectin Topical Parasiticide is presented as a colorless to yellow, ready-to-use solution contained in single-dose tubes, intended for topical (dermal) application in dogs six weeks of age and older, and cats eight weeks of age and older. Each tube is formulated to deliver a minimum dosage of 2.7 mg/lb (6 mg/kg) of body weight of selamectin. The chemical structure of selamectin is defined as (5Z,25S)-25-cyclohexyl-4'-O-de(2,6-dideoxy-3-O-methyl-α-L-arabino-hexopyranosyl)-5-demethoxy-25-de(1-methylpropyl)-22,23-dihydro-5-hydroxyiminoavermectin A1a.

Uses and Indications

This drug is indicated for the prevention and control of flea infestations (Ctenocephalides felis) and heartworm disease caused by Dirofilaria immitis in dogs six weeks of age or older and cats eight weeks of age or older.

In dogs, this drug is also indicated for the treatment and control of ear mite infestations (Otodectes cynotis), sarcoptic mange (Sarcoptes scabiei), and control of tick infestations due to Dermacentor variabilis.

In cats, the drug is indicated for the treatment and control of ear mite infestations (Otodectes cynotis), roundworm (Toxocara cati) infections, and intestinal hookworm (Ancylostoma tubaeforme) infections.

The drug should be administered topically once a month to effectively prevent heartworm disease and to prevent and control flea infestations.

Dosage and Administration

The recommended minimum dose of Selamectin is 2.7 mg per pound (6 mg/kg) of body weight. The entire contents of a single dose tube should be administered topically, or two tubes may be used in combination for dogs weighing over 130 pounds.

For Cats:

• For cats weighing up to 5 lbs, use the mauve package containing 15 mg of Selamectin, with an administered volume of 0.25 mL.

• For cats weighing 5.1–15 lbs, use the blue package containing 45 mg of Selamectin, with an administered volume of 0.75 mL.

• For cats weighing 15.1–22 lbs, use the taupe package containing 60 mg of Selamectin, with an administered volume of 1.0 mL.

• For cats over 22 lbs, the appropriate combination of tubes should be used.

For Dogs:

• For dogs weighing up to 5 lbs, use the mauve package containing 15 mg of Selamectin, with an administered volume of 0.25 mL.

• For dogs weighing 5.1–10 lbs, use the purple package containing 30 mg of Selamectin, with an administered volume of 0.25 mL.

• For dogs weighing 10.1–20 lbs, use the brown package containing 60 mg of Selamectin, with an administered volume of 0.5 mL.

• For dogs weighing 20.1–40 lbs, use the red package containing 120 mg of Selamectin, with an administered volume of 1.0 mL.

• For dogs weighing 40.1–85 lbs, use the teal package containing 240 mg of Selamectin, with an administered volume of 2.0 mL.

• For dogs weighing 85.1–130 lbs, use the plum package containing 360 mg of Selamectin, with an administered volume of 3.0 mL.

• For dogs over 130 lbs, the appropriate combination of tubes should be used.

Selamectin is recommended for use in dogs 6 weeks of age and older and in cats 8 weeks of age and older. A veterinarian or veterinary technician should demonstrate or instruct the pet owner on the appropriate technique for applying Selamectin topically to dogs and cats prior to first use.

For the prevention and control of flea infestations, Selamectin should be administered at monthly intervals throughout the flea season. For the prevention of heartworm disease, Selamectin must be administered on a monthly basis. For the treatment of ear mite infestations, Selamectin should be administered once as a single topical dose. For the treatment of sarcoptic mange in dogs, Selamectin should also be administered once as a single topical dose. For the control of tick infestations in dogs, Selamectin should be administered monthly. For the treatment and control of intestinal hookworm and roundworm infections, Selamectin should be applied once as a single topical dose.

Contraindications

Use of this product is contraindicated in sick, debilitated, or underweight animals due to the potential for adverse effects in these populations.

Additionally, the product should not be applied to broken skin, as it contains alcohol, which may cause irritation. Application is also contraindicated when the haircoat is wet, as this may affect the product's efficacy.

To prevent unintended exposure, avoid contact between the product and fingers. It is essential to wash hands thoroughly after use and to remove any product that comes into contact with the skin immediately with soap and water. In the event of human ingestion, seek medical attention promptly.

Warnings and Precautions

Selamectin is intended solely for veterinary use and must be kept out of reach of children. It is important to note that Selamectin may cause skin and eye irritation in humans. Reports of adverse reactions such as hives, itching, and skin redness have been documented. Individuals with a known hypersensitivity to Selamectin should exercise caution or consult a healthcare professional prior to use.

The formulation of Selamectin includes isopropyl alcohol and the preservative butylated hydroxytoluene (BHT). Following application, it is essential to wash hands thoroughly and to remove any product that may have come into contact with the skin using soap and water. In the event of eye contact, it is critical to flush the eyes copiously with water. If contact lenses are being worn, they should be removed after rinsing the eyes initially, and rinsing should continue for 5 to 10 minutes. Medical attention should be sought immediately. In case of accidental ingestion by a human, a physician should be contacted without delay. Additionally, Selamectin is flammable; therefore, it should be kept away from heat, sparks, open flames, or other ignition sources. It is contraindicated for use in sick, debilitated, or underweight animals.

Prior to administering Selamectin, it is recommended that dogs be tested for existing heartworm infections. If a heartworm infection is confirmed, the veterinarian may decide to treat the dog to eliminate adult heartworms, as Selamectin is not effective against adult Dirofilaria immitis. While Selamectin may reduce the number of circulating microfilariae, it does not clear them from the bloodstream. Notably, hypersensitivity reactions have not been observed in dogs with patent heartworm infections treated with Selamectin.

To ensure the safety and efficacy of treatment, it is advisable to conduct laboratory tests on dogs 3 to 4 months after initiating Selamectin to confirm their negative heartworm status. For cats aged 6 months or older, testing for existing heartworm infections may be warranted before starting treatment with Selamectin, at the veterinarian's discretion.

In the event of accidental ingestion by a human, immediate medical assistance should be sought. If contact with the eyes occurs, it is imperative to flush the eyes thoroughly with water and seek medical attention if irritation persists.

Side Effects

Adverse reactions associated with the use of the product have been observed in both pre-approval clinical trials and post-approval experiences.

In pre-approval clinical trials involving 691 treated cats, approximately 1% of participants experienced transient localized alopecia, with or without inflammation, at or near the site of application. Other adverse signs were reported in ≤0.5% of 1,743 treated cats and dogs, including vomiting, loose stool or diarrhea (with or without blood), anorexia, lethargy, salivation, tachypnea, and muscle tremors.

Post-approval experience data from 2021 revealed additional adverse reactions reported in dogs and cats. In dogs, the most frequently reported reactions, listed in decreasing order of frequency, included lethargy, vomiting, diarrhea, anorexia, generalized pruritus, seizures, application site reactions (such as alopecia, lesions, erythema, pruritus, and inflammation), tremors, ataxia, and death. Dermatitis was also noted among the reported reactions.

In cats, the adverse reactions reported, also listed in decreasing order of frequency, included application site reactions (which encompassed alopecia, lesions, erythema, pruritus, inflammation, vesicles, blisters, and excoriations), lethargy, anorexia, vomiting, death, generalized pruritus, diarrhea, ataxia, fever, generalized alopecia, tremors, hypersalivation, dermatitis, and seizures.

It is important to note that the product is not intended for human use and should be kept out of reach of children. In humans, Selamectin may cause skin and eye irritation, and reactions such as hives, itching, and skin redness have been reported. Individuals with known hypersensitivity to Selamectin should exercise caution or consult a healthcare professional before use. Additionally, the product should not be administered to sick, debilitated, or underweight animals.

Drug Interactions

Selamectin is indicated for use in dogs and cats; however, it is important to note that it is not effective against adult Dirofilaria immitis (heartworm) and does not eliminate microfilariae. Prior to the administration of Selamectin, it is recommended that dogs be tested for existing heartworm infections. In cases where a dog tests positive for adult heartworms, appropriate treatment should be advised by a veterinarian.

For cats aged six months and older, testing for existing heartworm infections is also advisable before initiating treatment with Selamectin. In cats that are already infected with adult heartworms, Selamectin can be administered monthly to prevent further infections.

Selamectin has demonstrated a favorable safety profile and can be used concurrently with other veterinary products, including vaccines, anthelmintics, antiparasitics, antibiotics, steroids, collars, shampoos, and dips, without significant interactions.

Packaging & NDC

The table below lists each NDC Code for Selamectin veterinary formulations. Columns show Packaging, Formulation Type, and Active Ingredient Strength.

Pediatric Use

Selamectin is indicated for use in dogs six weeks of age and older and in cats eight weeks of age and older. The recommended minimum dosage for both species is 2.7 mg selamectin per pound (6 mg/kg) of body weight. For dogs weighing over 130 pounds, two tubes may be used in combination to achieve the appropriate dosage.

Dosing recommendations for cats are as follows:

• Up to 5 lbs: 15 mg (Mauve tube)

• 5.1–15 lbs: 45 mg (Blue tube)

• 15.1–22 lbs: 60 mg (Taupe tube)

For dogs, the dosing recommendations are:

• Up to 5 lbs: 15 mg (Mauve tube)

• 5.1–10 lbs: 30 mg (Purple tube)

• 10.1–20 lbs: 60 mg (Brown tube)

• 20.1–40 lbs: 120 mg (Red tube)

• 40.1–85 lbs: 240 mg (Teal tube)

• 85.1–130 lbs: 360 mg (Plum tube)

Selamectin has been demonstrated to be safe in puppies six weeks of age and older and in kittens eight weeks of age and older. However, caution is warranted as a case was reported where a malnourished and underweight kitten, estimated to be 5–6 weeks old, died 8.5 hours after receiving a single treatment of selamectin at the recommended dosage. In safety studies, selamectin was administered at 1, 3, 5, and 10 times the recommended dose to six-week-old puppies and kittens without any adverse reactions observed.

Geriatric Use

Elderly patients may present unique considerations when administering Selamectin. It is important to note that Selamectin is not recommended for use in sick, debilitated, or underweight animals, which may include some geriatric patients. Prior to the administration of Selamectin, it is advised that dogs be tested for existing heartworm infections to ensure safety and efficacy. For cats aged 6 months and older, testing for heartworm infections may also be considered at the veterinarian's discretion before initiating treatment with Selamectin.

In dogs that are already infected with adult heartworms, Selamectin can be administered monthly to prevent further infections. The safety of Selamectin has been established in over 100 different pure and mixed breeds of healthy dogs and more than 15 different pure and mixed breeds of healthy cats, including pregnant and lactating females, as well as breeding males and females. Puppies as young as six weeks and kittens eight weeks and older have also been included in safety assessments.

However, caution is warranted, particularly in cases where the animal's health status is compromised. A notable incident involved a kitten, estimated to be 5–6 weeks old and weighing 0.3 kg, which died 8.5 hours after receiving a single treatment of Selamectin at the recommended dosage. This kitten exhibited clinical signs such as muscle spasms, salivation, and neurological symptoms, and was identified as a stray with an unknown health history, being malnourished and underweight.

In controlled safety studies, Selamectin was administered at doses ranging from 1 to 10 times the recommended dose to six-week-old puppies, with no adverse reactions reported. Additionally, in a topical safety study involving avermectin-sensitive collies, salivation was noted across all treatment groups, including the vehicle control. Furthermore, Selamectin was applied at four times the recommended dose to heartworm-infected cats without any observed adverse reactions.

Given these findings, it is essential for veterinarians to carefully assess the health status of geriatric patients and consider potential risks before prescribing Selamectin. Monitoring for adverse reactions and adjusting dosages as necessary may be prudent in this population.

Pregnancy

Selamectin has been evaluated for safety in over 100 different pure and mixed breeds of healthy dogs and over 15 different pure and mixed breeds of healthy cats, including pregnant and lactating females. The data suggest that Selamectin can be administered to pregnant patients without significant risk.

It is important to note that Selamectin is not effective against adult Dirofilaria immitis (heartworm) and, while treatment may lead to a decrease in the number of circulating microfilariae, it does not facilitate microfilariae clearance. However, dogs and cats that are already infected with adult heartworms can safely receive Selamectin to prevent further infections.

Healthcare professionals should consider these factors when prescribing Selamectin to pregnant patients or those of childbearing potential, ensuring that the benefits outweigh any potential risks.

Lactation

Selamectin has been tested for safety in over 100 different pure and mixed breeds of healthy dogs and over 15 different pure and mixed breeds of healthy cats, including pregnant and lactating females. While specific data on excretion in human breast milk and effects on breastfed infants are not provided, the safety profile in lactating animals suggests a potential for cautious use in lactating mothers.

Lactating mothers should consider the benefits and risks of using Selamectin, particularly in the context of treating pets that may be infected with adult heartworms. Dogs and cats infected with adult heartworms can safely be administered Selamectin, which may indirectly influence the decision-making process for lactating mothers who are pet owners.

Renal Impairment

Patients with renal impairment should be approached with caution when considering the use of selamectin. It is important to note that selamectin should not be used in sick, debilitated, or underweight animals, as these conditions may exacerbate the risks associated with treatment. Prior to administration, dogs must be tested for existing heartworm infections, and at the veterinarian's discretion, infected dogs may require treatment to remove adult heartworms.

While selamectin is not effective against adult Dirofilaria immitis, it may reduce the number of circulating microfilariae; however, it does not facilitate microfilariae clearance. In safety studies, selamectin was administered at various multiples of the recommended dose to both puppies and kittens without adverse reactions, indicating a favorable safety profile in these populations. However, caution is warranted, particularly in cases of accidental oral ingestion, where salivation and intermittent vomiting were observed in cats.

Given the potential for adverse effects in patients with compromised health status, careful monitoring and consideration of the patient's overall condition are essential when administering selamectin to those with reduced renal function.

Hepatic Impairment

Selamectin is contraindicated in patients with hepatic impairment, particularly in sick, debilitated, or underweight animals. Prior to the administration of Selamectin, it is essential for veterinarians to test dogs for existing heartworm infections. If a dog is found to be infected, treatment to remove adult heartworms should be considered at the veterinarian's discretion.

Selamectin is not effective against adult Dirofilaria immitis, and while treatment may reduce the number of circulating microfilariae, it does not facilitate their clearance. Hypersensitivity reactions have not been reported in dogs with patent heartworm infections treated with Selamectin.

In safety studies, Selamectin has been administered to various breeds of healthy dogs and cats, including pregnant and lactating females, as well as young animals, without adverse reactions. However, caution is warranted, as a case was reported where a malnourished and underweight kitten died shortly after receiving Selamectin, exhibiting clinical signs such as muscle spasms and neurological symptoms.

While Selamectin has been tested at doses up to ten times the recommended amount in six-week-old puppies without adverse effects, the safety of Selamectin in patients with hepatic impairment has not been specifically established. Therefore, careful monitoring and consideration of the animal's overall health status are advised when administering Selamectin to patients with compromised liver function.

Overdosage

In the event of an overdose, it is imperative to seek immediate medical attention. Healthcare professionals should be alerted to any instances of ingestion by a human, as prompt intervention is crucial for patient safety.

Upon recognition of an overdose, the following steps are recommended:

1. Immediate Action: Contact a physician or poison control center without delay. This ensures that the patient receives appropriate guidance and management based on the specific circumstances of the overdose.

2. Monitoring Symptoms: Healthcare providers should be vigilant for potential symptoms associated with the overdose. While specific symptoms are not detailed in the provided information, general signs of overdose may include altered mental status, respiratory distress, or cardiovascular instability.

3. Management Procedures: The management of an overdose may involve supportive care, symptomatic treatment, and, if applicable, the administration of antidotes. The specific approach will depend on the substance involved and the clinical presentation of the patient.

In summary, immediate medical consultation is essential in cases of overdose to facilitate timely and effective management.

Nonclinical Toxicology

Selamectin has been evaluated for teratogenic effects in over 100 different pure and mixed breeds of healthy dogs and more than 15 different pure and mixed breeds of healthy cats, including pregnant and lactating females, and has been found to be safe.

In terms of non-teratogenic effects, a case was reported where a kitten, estimated to be 5–6 weeks old and weighing 0.3 kg, died 8.5 hours after receiving a single treatment of selamectin at the recommended dosage. The kitten exhibited clinical signs such as muscle spasms, salivation, and neurological symptoms. Additionally, hypersensitivity reactions were not observed in dogs with patent heartworm infections that were administered selamectin.

In safety studies, selamectin was administered at 1, 3, 5, and 10 times the recommended dose to six-week-old puppies, with no adverse reactions noted. The safety of selamectin was also assessed in cases of accidental oral ingestion. Oral administration of selamectin at the recommended topical dose to 5- to 8-month-old beagles did not result in any adverse reactions. In a pre-clinical study involving ivermectin-sensitive collies, oral doses of 2.5, 10, and 15 mg/kg were given without adverse reactions; however, one collie became ataxic for several hours after receiving 5 mg/kg orally, but did not exhibit any further adverse reactions after subsequent doses of 10 and 15 mg/kg.

In a topical safety study with avermectin-sensitive collies, salivation was observed across all treatment groups, including the vehicle control, when selamectin was applied at 1, 3, and 5 times the recommended dose. Selamectin was also administered at 3 times the recommended dose to heartworm-infected dogs, with no adverse effects reported. In safety studies involving six-week-old kittens, selamectin was applied at 1, 3, 5, and 10 times the recommended dose, and no adverse reactions were observed. However, oral administration of the recommended topical dose of selamectin to cats resulted in salivation and intermittent vomiting. In cases where selamectin was applied at 4 times the recommended dose to patent heartworm-infected cats, no adverse reactions were noted.

Selamectin is classified as a macrocyclic lactone compound, which effectively prevents the development of adult heartworms when administered to dogs and cats within one month of exposure to infective Dirofilaria immitis larvae. The efficacy of macrocyclic lactones decreases below 100% in dogs if administration occurs more than two months after exposure to infective larvae. Therefore, in heartworm-endemic regions, delaying the initiation of heartworm prevention with selamectin beyond two months after the first exposure to infective larvae, or allowing gaps of more than two months in the administration of selamectin during periods of heartworm transmission, increases the risk of heartworm acquisition in the animal.

Postmarketing Experience

Adverse events reported in postmarketing experience for dogs include lethargy, vomiting, diarrhea, anorexia, generalized pruritus, seizures, application site reactions (such as alopecia, lesions, erythema, pruritus, and inflammation), tremors, ataxia, death, and dermatitis, listed in decreasing order of frequency.

For cats, the reported adverse events, also in decreasing order of frequency, include application site reactions (including alopecia, lesions, erythema, pruritus, inflammation, vesicles, blisters, and excoriations), lethargy, anorexia, vomiting, death, generalized pruritus, diarrhea, ataxia, fever, generalized alopecia, tremors, hypersalivation, dermatitis, and seizures.

Following treatment with Selamectin, transient localized alopecia with or without inflammation at or near the site of application was observed in approximately 1% of 691 treated cats. Other signs observed in ≤0.5% of 1743 treated cats and dogs included vomiting, loose stool or diarrhea with or without blood, anorexia, lethargy, salivation, tachypnea, and muscle tremors.

Reports of death have been noted in both dogs and cats. Severe application site reactions, such as blisters, scabbing, and infection, have been documented in cats. It is important to note that the following adverse events are based on post-approval adverse drug experience reporting for Selamectin. Not all adverse events are reported to the FDA/CVM, and it is not always possible to reliably estimate the frequency of adverse events or establish a causal relationship to product exposure using this data.

Patient Counseling

Healthcare providers should advise patients that Selamectin is a topical parasiticide intended for use in dogs six weeks of age and older and cats eight weeks of age and older. It is effective in killing adult fleas, preventing flea eggs from hatching, preventing heartworm disease, and protecting against other parasites.

It is important to inform patients that Selamectin should not be used in sick, debilitated, or underweight animals. Prior to administering Selamectin, dogs should be tested for heartworm disease. If a dog tests positive for adult heartworms, the veterinarian can recommend appropriate treatment, as dogs infected with adult heartworms can safely receive Selamectin. For cats older than six months, the veterinarian may also decide to test for heartworm disease before prescribing Selamectin, which can be given to cats infected with adult heartworms to prevent further infections.

Patients should be instructed to apply Selamectin monthly and to immediately apply a missed dose if they forget. They should resume the monthly application schedule and notify their veterinarian. If patients administer more than the prescribed amount of Selamectin, they should contact their veterinarian for guidance.

Healthcare providers should emphasize that Selamectin should not be massaged into the skin, applied when the haircoat is wet, or applied to broken skin, as it contains alcohol. Patients may notice stiff hair, clumping, discoloration, or a slight powdery residue at the application site; these effects are typically temporary and do not compromise the product's safety or effectiveness.

Bathing or shampooing the dog two or more hours after treatment will not diminish Selamectin's effectiveness against fleas or heartworm, and bathing or shampooing the cat 24 hours after treatment will also not reduce effectiveness. Patients should avoid contact with the application site while it is wet and may hold or play with their pet once the area is dry.

It is crucial to inform patients that Selamectin may cause skin and eye irritation in humans, with reported reactions including hives, itching, and skin redness. Individuals with known hypersensitivity to Selamectin should use the product with caution or consult a healthcare professional. Patients should wash their hands after applying Selamectin and immediately wash off any product that comes into contact with their skin using soap and water. In the event of human ingestion, patients should seek medical attention immediately.

Storage and Handling

The product is available in various package configurations, with specific NDC numbers assigned for identification. Currently, there are no specific storage instructions or handling details provided. It is advisable for healthcare professionals to follow standard storage practices for pharmaceutical products, ensuring that the product is stored in a suitable environment to maintain its integrity and efficacy.

Additional Clinical Information

No further data are available.

Drug Information (PDF)

This document includes the full labeling information for Selamectin, as submitted by ZYVET ANIMAL HEALTH INC. for veterinary use. It may include dosage by species, withdrawal periods, and administration instructions.

View veterinary label (PDF)