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Clinical particulars
Target species
Dogs and cats.
Indications for use, specifying the target species
Treatment and prevention of flea infestations (Ctenocephalides felis).
The preventive effect against re-infestations is a result of the adulticidal activity and the reduction in egg production and persists for up to 4 weeks after a single administration of the product.
The veterinary medicinal product can be used as part of a treatment strategy for the control of flea allergy dermatitis (FAD).
Contraindications
Do not use in dogs or cats under 14 weeks of age.
Do not use in case of known hypersensitivity to the active substance or to any of the excipients.
Special warnings for each target species
The veterinary medicinal product should be administered with food or immediately after feeding. The duration of efficacy may be reduced if the dose is administered on an empty stomach.
All dogs and cats within the household should be treated.
Fleas from pets often infest the animal’s basket, bedding and regular resting areas such as carpets and soft furnishings, which should be treated in case of massive infestation and at the beginning of the treatment with a suitable insecticide and vacuumed regularly.
Fleas may persist for a period of time after administration of the product due to the emergence of adult fleas from pupae already in the environment. Regular monthly treatments with Comfortis break the fleas’ life cycle and may be needed to control the flea population in contaminated households.
Special precautions for use
Special precautions for use in animals
Use with caution in dogs and cats with pre-existing epilepsy.
Accurate dosing is not possible in dogs weighing less than 1.3 kg and in cats weighing less than 1.2 kg. The use of the product in smaller dogs and smaller cats is therefore not recommended.
The recommended dosage regimen should be followed (see overdose section).
Special precautions to be taken by the person administering the veterinary medicinal product to animals
Accidental ingestion may cause adverse reactions.
Children should not come into contact with the veterinary medicinal product.
In case of accidental ingestion, seek medical advice immediately and show the package leaflet or the label to the physician.
Wash hands after use.
Adverse reactions (frequency and seriousness)
Dogs
In dogs, a commonly observed adverse reaction is vomiting, which occurs in the first 48 hours after dosing and is most likely caused by a local effect on the small intestines. On the day of, or the day following administration of spinosad at a dose of 45–70 mg/kg bodyweight, the observed incidence of vomiting in the field trial was 5.6%, 4.2% and 3.6% after the first, second and third monthly treatments respectively. The incidence of vomiting observed after the first and second treatments was higher (8%) in dogs dosed at the upper end of the dose band. In the majority of cases, vomiting was transient, mild and did not require symptomatic treatment.
In dogs lethargy, anorexia and diarrhoea were uncommon and muscle tremor, ataxia and seizures were rare. In very rare cases, blindness, impaired vision and other eye disorders were observed.
Cats
In cats, a commonly observed adverse reaction is vomiting, which occurs in the first 48 hours afterdosing and is most likely caused by a local effect on the small intestines. On the day of, or the day following administration of spinosad at a dose of 50–75 mg/kg bodyweight, the observed incidence of vomiting in the global field trial was between 6% and 11% in the first three months of treatment. In the majority of cases, vomiting was transient, mild and did not require symptomatic treatment.
Other commonly observed adverse reactions in cats were diarrhoea and anorexia. Lethargy, loss of condition and salivation were uncommon. Seizures were rare adverse reactions.
The frequency of adverse reactions is defined using the following convention:
very common (more than 1 in 10 animals displaying adverse reactions during the course of one treatment)
common (more than 1 but less than 10 animals in 100 animals)
uncommon (more than 1 but less than 10 animals in 1,000 animals)
rare (more than 1 but less than 10 animals in 10,000 animals)
very rare (less than 1 animal in 10,000 animals, including isolated reports).
Use during pregnancy, lactation or lay
Pregnancy:
Laboratory studies in rats and rabbits have not produced any evidence of teratogenic, foetotoxic or maternotoxic effects.
In pregnant dogs (bitches), the safety of spinosad has not been sufficiently established. The safety of spinosad in pregnant cats (queens) has not been evaluated.
Lactation:
In dogs, spinosad is excreted in the colostrum and milk of lactating bitches and it is therefore assumed that spinosad is excreted in the colostrum and milk of lactating queens. As the safety of this for suckling puppies and kittens has not been established, the product should only be used during pregnancy and lactation according to the benefit-risk assessment by the responsible veterinarian.
Fertility:
Laboratory studies in rats and rabbits have not produced any evidence of any effect on the reproductive capacity in males and females.
The safety of the product in male dogs and male cats used for breeding has not been determined.
Interaction with other medicinal products and other forms of interaction
Spinosad has been shown to be a substrate for P-glycoprotein (PgP). Spinosad could therefore interact with other PgP-substrates (for example, digoxin, doxorubicin) and possibly enhance adverse reactions from such molecules or compromise efficacy.
Post marketing reports, following the concomitant use of Comfortis with ‘off label’ high dose ivermectin indicate that dogs have experienced trembling/twitching, salivation/drooling, seizures, ataxia, mydriasis, blindness and disorientation.
Amounts to be administered and administration route
For oral use.
The veterinary medicinal product should be administered with food or immediately after feeding.
Dogs:
The veterinary medicinal product should be administered in accordance with the following table to ensure a dose of 45-70 mg/kg bodyweight for dogs:
Dog bodyweight (kg)
No. of tablets & strength (mg spinosad)
1.3-2
1 x 90 mg tablet
2.1-3
1 x 140 mg tablet
3.1-3.8
1 x 180 mg tablet
3.9-6
1 x 270mg tablet
6.1-9.4
1 x 425 mg tablet
9.5-14.7
1 x 665 mg tablet
14.8-23.1
1 x 1040 mg tablet
23.2-36
1 x 1620 mg tablet
36.1-50.7
1 x 1620 mg tablet + 1 x 665 mg tablet
50.8-72
2 x 1620 mg tablets

Cats:
The Veterinary medicinal product should be administered in accordance with the following table to ensure a dose of 50-75 mg/kg bodyweight for cats:
Cat bodyweight (kg)
No. of tablets & strength (mg spinosad)
1.2-1.8
1 x 90 mg tablets
1.9-2.8
1 x 140 mg tablet
2.9-3.6
1 x 180 mg tablet
3.7-5.4
1 x 270 mg tablet
5.5-8.5*
1 x 425 mg tablet
*Cats over 8.5 kg: give the appropriate combination of tablets
Comfortis tablets are chewable and palatable for dogs. If the dog or cat does not accept the tablets directly they may be administered with food, or directly by opening the animal’s mouth and placing the tablet onto the back of the tongue.
If vomiting occurs within an hour of administration and the tablet is visible, re-dose the animal with another full dose to ensure maximum effectiveness of the product.
If a dose is missed, administer the veterinary medicinal product with the next offering of food and resume a monthly dosing schedule.
The veterinary medicinal product may safely be given at monthly intervals at the recommended dose.
The residual insecticidal properties of the product persist for up to 4 weeks after a single administration. If fleas reappear in the fourth week, the treatment interval can be shortened by up to 3 days in dogs. In cats, the full 4 week gap between treatments should be maintained, even if fleas reappear before the end of the 4 weeks.
Seek veterinary advice regarding information on the optimal time to start treatment with this product.
Overdose (symptoms, emergency procedures, antidotes), if necessary
There is no antidote available. In case of adverse clinical signs, the animal should be treated symptomatically.
Dogs:
The incidence of vomiting on the day of, or the day after, dosing has been observed to increase as a function of dose. Vomiting is most likely caused by a local effect on the small intestines. At doses in excess of the recommended dose vomiting becomes a very common event. At doses of approximately 2.5 times the recommended dose, spinosad caused vomiting in the vast majority of dogs.
At doses up to 100 mg/kg bodyweight per day for 10 days, the only clinical symptom of overdose was vomiting, which occurred usually within 2.5 hours of dosing. Mild elevations of ALT (alanine aminotransferase) occurred in all dogs treated with Comfortis, although values returned to their baseline by day 24. Phospholipidosis (vacuolation of lymphoid tissues) also occurred; although this was not related to clinical signs in dogs treated up to 6 months.
Cats:
After a single acute overdose corresponding to 1.6 times the maximum label dose, spinosad caused vomiting in approximately half of the cats, and depression, pacing/panting and severe diarrhoea on rare occasions.
At doses of 75 to 100 mg/kg bodyweight per day for 5 days, given at monthly intervals for a period of six months, the most commonly observed clinical sign was vomiting. Furthermore, a reduction of food intake was observed in females, however a significant reduction in their bodyweight was not observed.
Phospholipidosis (vacuolation of the cells of the liver, adrenal gland and lung) also occurred. Also noted were diffuse hepatocellular hypertrophy in males and females, and this finding correlated with higher pooled mean liver weights. However there was no evidence in the clinical observations and clinical chemistry parameters that indicated any loss in organ function.
Withdrawal period
Not applicable.