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Spinosad. Palatable, beef flavoured monthly tablet.

COMFORTIS® chewable tablets for dogs
Comfortis chewable tablets are unscored tan to brown, or speckled, round, flat, bevelled-edge tablets, plain on one side and debossed with a number as listed below on the other side:
425mg: 4229
1040mg: 4231
1620mg: 4227
Unscored tan to brown, or speckled, round, flat, bevelled edge tablets, plain on one side and debossed with a number underlined as listed below on the other:
270mg: 4223
665mg: 4230
In dogs for -
The treatment and prevention of flea infestations (Ctenocephalides felis).
The preventative 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.
Comfortis tablets can be used as part of a treatment strategy for the control of Flea Allergy Dermatitis (FAD).
Dosage and Administration
Comfortis tablets are administered orally at a recommended dose of 45-70mg/kg bodyweight at monthly intervals.
Weight of dog (kg)
Number of tablets and tablet strength (mg spinosad)
3.9 - 6.0
6.1 - 9.4
9.5 - 14.7
14.8 - 23.1
23.2 - 36.0
36.1 - 50.7
50.8 - 72.0
1 x 270 tablet
1 x 425 tablet
1 x 665 tablet
1 x 1040 tablet
1 x 1620 tablet
1 x 1620 + 1 x 665 tablets
2 x 1620 tablets
Comfortis chewable tablets can be administered at the recommended dose with the following advice:
Comfortis tablets 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.
If vomiting occurs within an hour of administration and the tablet is visible, re-dose with another full dose.
If a dose is missed, administer the veterinary medicinal product with the next offering of food and resume a monthly dosing schedule.
In the case of heavy flea infestations, 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. This is achieved by the capability of spinosad to rapidly kill adult fleas and therefore greatly reduce egg production.
All dogs in the household should be treated. Cats in the household should be treated with a product authorised for use in that species.
Contra-indications, Warnings, etc
Do not use in dogs under 14 weeks of age.
Do not use in case of known hypersensitivity to the active substance or to any of the excipients.
Special precautions for use in animals
Use with caution in dogs with pre-existing epilepsy.
Accurate dosing is not possible in dogs weighing less than 3.9kg and therefore the use of Comfortis tablets is not recommended in these patients
Use during pregnancy, lactation or lay
In pregnant dogs, the safety of spinosad has not been sufficiently established.
Spinosad is excreted in the colostrum and milk of lactating bitches and the safety of this for suckling puppies has not been sufficiently established. Therefore, during pregnancy and lactation, the product should only be used according to the benefit/risk assessment by the responsible veterinary surgeon.
The safety of spinosad in male dogs used for breeding has not been determined.
Spinosad has been shown to be a substrate for P-glycoprotein (PgP). Spinosad could therefore interact with other PgP-substrates (for example, digoxin and 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 doses of ivermectin indicate that dogs have experienced trembling/twitching, salivation/drooling, seizures, ataxia, mydriasis, blindness and disorientation.
Adverse Events
The most frequently observed adverse event is vomiting, which most commonly 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 trials 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.
Other adverse reactions are uncommon or rare, and include lethargy, anorexia, diarrhoea, ataxia and seizures.
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 majority of dogs.
There is no antidote available. In the event of an adverse reaction, the attending veterinary surgeon may treat clinical signs symptomatically if deemed necessary.
Operator Warnings
Accidental ingestion may cause adverse reactions.
In case of accidental ingestion, seek medical advice immediately and show package leaflet or label to the physician.
Wash hands after administering product.
Keep out of the reach and sight of children
Withdrawal Period
Not applicable
Pharmaceutical Precautions
For animal treatment only.
Keep the blister pack in the outer carton.
Any unused veterinary medicinal product or waste materials derived from such veterinary medicinal products should
be disposed of in accordance with local requirements.
Do not use after the expiry date
Legal Category POM
Package Quantities
Clear PTCFE/PE/PVC blister pack sealed with aluminium foil containing six chewable tablets.
Carton packages containing one or six blister packs.
Not all pack sizes may be marketed.
Further Information
Comfortis starts killing fleas 30 minutes after administration; 100% of fleas are dead/moribund within 4 hours post-treatment. Insecticidal activity against new infections persists for up to 4 weeks.
The insecticidal activity of spinosad is characterised by nervous excitation leading to muscle contractions and tremors, prostration, paralysis and rapid death of the flea. These effects are caused primarily by activation of nicotinic acetyl choline receptors (nAChRs). Spinosad therefore has a different mode of action to other flea control or insect control products. It does not interact with known binding sites of other nicotinic or GABAergic insecticides such as neonicotinoids (imidacloprid or nitenpyram), fiproles (fipronil), milbemycins, avermectins (e.g. selamectin) or cyclodienes, but through a novel insecticidal mechanism.
Approximately 90% of spinosad is comprised of spinosyns A and D. Of that 90%, the ratio of spinosyn A to A+D is 0.85 when calculated as spinosyn A/spinosyn A+D. The consistency of this figure in pharmacokinetic and other studies indicates comparability in the absorption, metabolism and elimination of the two major spinosyns.


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