Brand: CROSSBLOCK II
FORMULATION: «spot-on» solution for topical administration on the back of the animals (also called pipettes, squeeze-ons, drop-ons, etc.)
- IMIDACLOPRID: 91 mg/mL (= 9.1%)
- PYRIPROXYFEN: 4.6 mg/mL (= 0.46%)
CHEMICAL CLASS of the active ingredient(s):
- Imidacloprid: NEONICOTINOID
- Pyriproxyfen: JUVENILE HORMONE ANALOGUE
INDICATIONS: DOGS and CATS
PARASITES CONTROLLED (spectrum of activity)
- Dogs, small 3 to 10 lbs. bw: 1 pipette with 0.014 fl.oz = 0.4 mL (equivalent >8.1 mg/kg imidacloprid and >0.4 mg/kg mg/kg pyriproxyfen)
- Dogs, medium 11 to 20 lbs. bw: 1 pipette with 0.034 fl.oz = 1 mL (equivalent to 20.2 - 10.0 mg/kg imidacloprid and 1.0 - 0.5 mg/kg pyriproxyfen)
- Dogs, large 21 to 55 lbs. bw: 1 pipette with 0.084 fl.oz = 2.5 mL (equivalent to 25.1 - 9.1 mg/kg imidacloprid and 1.3 - 0.5 mg/kg pyriproxyfen)
- Dogs, very large >55 lbs. bw: 1 pipette with 0.135 fl.oz = 4.0 mL (equivalent to <14.6 mg/kg imidacloprid and <0.7 mg/kg pyriproxyfen)
- Cats, kitten 2 to 5 lbs. bw: 1 pipette with 0.0078 fl.oz = 0.23 mL (equivalent to >9.3 mg/kg imidacloprid and >0.5 mg/kg mg/kg pyriproxyfen)
- Cats, medium 5 to 9 lbs. bw: 1 pipette with 0.014 fl.oz = 0.4 mL (16.1 - 8.9 mg/kg imidacloprid and 0.8 - 0.5 mg/kg pyriproxyfen
- Cats, large >9 lbs. bw: 1 pipette with 0.027 fl.oz = 0.8 mL (equivalent to <17.8 mg/kg imidacloprid and <0.9 mg/kg mg/kg pyriproxyfen)
- LD50 (acute oral) in rats: 1732-1943 mg/kg (according to MSDS of ADVANTAGE II)
- LD50 (acute dermal) in rats: >2000 mg/kg (according to MSDS of ADVANTAGE II)
- Estimated Toxicity Class according to the WHO: III moderately hazardous (based on the imidacloprid LD50, learn more)
Suspected poisoning? Read the articles on imidacloprid safety and pyriproxyfen safety in this site.
WARNING !!!: Never use on cats pipettes approved only for dogs. Never use on small dogs pipettes approved for large dogs. Learn more about spot-ons and their safety.
You may be interested in the following articles in this site dealing with the general safety of veterinary products:
- Safety for humans
- Safety for domestic animals
- Safety for the environment
- Hazard classifications of pesticides
Risk of resistance? YES, low in fleas, mainly the cat flea, Ctenocephalides felis.
So far there are no reports on flea resistance to imidacloprid, more than 20 years after its introduction for flea control. However, fleas have developed resistance to several other insecticides (e.g. carbamates, organophosphates and pyrethroids) and are certainly capable of becoming resistant to imidacloprid as well. Experience shows that prolonged and uninterrupted use of any insecticide against fleas (including imidacloprid) bears the risk of resistance development. There are no reports on resistance of fleas to pyriproxyfen either.
Alternatives to prevent resistance through product rotation:
- Amitraz (T*): toxic to cats!
- Carbamates (F+T*), e.g. carbaryl, propoxur
- Indoxacarb (F*)
- Insect Development Inhibitors (F*), e.g. lufenuron
- Isoxazolines (F+T*), e.g. afoxolaner, fluralaner, sarolaner
- Macrocyclic lactones (F*), e.g. selamectin
- Organophosphates (F+T*), e.g. chlorpyrifos, coumaphos, diazinon, fenthion, etc.
- Phenylpyrazoles (F+T*), e.g. fipronil, pyriprole
- Pyrethroids (F+T*), e.g. cyphenothrin, cypermethrin, deltamethrin, etofenprox, flumethrin, permethrin, etc. toxic to cats!
- Spinosyns (F*), e.g. spinetoram, spinosad
*F = effective against fleas; T = effective against ticks.
These alternative products may not be available in all countries, or may not be available as spot-ons.
Resistance of fleas to carbamates, organophosphates and pyrethroids is not uncommon in several countries, including the USA.
Learn more about resistance and how it develops.
Are the active ingredients of this product ORIGINAL* or GENERICS**?
- Imidacloprid: GENERIC (introduced in the 1990s by BAYER)
- Pyriproxyfen: GENERIC (introduced in the 1980s by SUMITOMO)
*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.
CROSSBLOCK II is a generic version of ADVANTAGE II (introduced by BAYER).
COUNTRIES where this product is marketed (maybe under another TM): USA
GENERIC BRANDS available? YES, this brand is a generic brand itself.
Click here to learn more about GENERIC vs. ORIGINAL drugs.
CROSSBLOCK II is generic version of BAYER's original ADVANTAGE II. Administered about every 4 weeks it controls established flea infestations and prevents flea populations to develop in the pets' environment, but only if all the dogs and cats in the same household are treated against fleas.
Imidacloprid is a broad-spectrum neonicotinoid insecticide introduced in the 1990s (by BAYER). It is ineffective against ticks and mites. It is abundantly used in pets, but very scarcely in livestock. It is massively used in agriculture and quite abundantly against household pests.
Pyriproxyfen (Nylar) is a veteran insect development inhibitor introduced in the 1980s (by SUMITOMO) scarcely used in pets. Its only effect is to stop development of flea eggs and larvae. It has no effect whatsoever against adult fleas.
This combination of two active ingredients of different chemical classes makes also sense regarding resistance prevention, because it means attacking fleas through two different mechanisms of action, which is vastly assumed to help preventing or at least delaying resistance development.
Topical products (mainly spot-ons and insecticide-impregnated collars) have some advantages over systemic products (mainly tablets for oral administration and injectables):
- Most topical products kill or sterilize the parasites before they bite and suck blood on the pet, whereas systemic products kill or sterilize the parasites only after their blood meal.
- Topical products cannot be vomited.
- Spot-ons and collars are very convenient to administer.
- There is a larger choice of topical products.
But topical products have also some disadvantages:
- Topical products contaminate the pet's hair coat and it is advisable for children and also adults to avoid contact with the pet for several days after treatment.
- Topical products may not control parasites in some parts of the pet's body (e.g. the ears, below the tail, between the legs, etc.), whereas systemic products reach the blood-sucking parasites through the blood wherever they are.
- Efficacy of topical products may be reduced or shortened through exposure to dirt, sun, shampooing, washing, rain, baths, etc., whereas efficacy of systemic products is independent from these factors.
For an overview and a list of the most popular pet antiparasitics for flea, tick, lice and/or mite control click here.
This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics.
Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.
In case of doubt contact the manufacturer or a veterinary professional.