Can dogs overdose on praziquantel?

Praziquantel (Droncit)

(For veterinary information only)

WARNING
The size of the tablet/medication is NOT an indication of a proper dose. Never administer any drug without your veterinarian's input. Serious side effects or death can occur if you use drugs on your pet without your veterinarian's advice. 

It is our policy not to give dosing information over the Internet.

Brand Name: Droncit, Interceptor Plus, Milbemax, Profender, Drontal, Drontal Plus, Sentinel Spectrum, Iverhart Plus, Virbantel, Iverhart Max

Available as injectable; 23 mg tablets for cats and 34 mg tablets for dogs; as a topical dewormer combined with emodepside; tablets for dogs combined with milbemycin and lufenuron; tablets for dogs including ivermectin and pyrantel pamoate

How this Medication is Used 

A member of the Taenia genus of tapeworms. Photo courtesy of CDC.

Praziquantel is primarily used against parasites known as cestodes (tapeworms). The common tapeworm of dogs and cats, Dipylidium caninum, is the usual target of this medication although praziquantel is also effective against less common types of tapeworms such as Taenia species and the more dangerous Mesocestoides species and Echinococcus species. Praziquantel is also effective against flukes.

A single treatment of praziquantel should clear a Dipylidium caninum infection although a second treatment is sometimes recommended if it is felt that immediate re-infection is likely. Immediate re-infection might take place if a heavy uncontrolled flea problem is in the pet's environment; Dipylidium caninum is contracted when an infected adult flea harboring a tapeworm larva is eaten.

Praziquantel is also available in combination with other single use oral dewormers as well as with more comprehensive monthly worm protection products. (Numerous brands are available. See the list above.) Such products provide regular deworming against assorted worm parasites. Plain praziquantel is available in non-prescription tablets that may be purchased at pet supply stores. Brand name products, combination products as described above, and injections are available only through veterinarians as they are prescription drugs.

As of late 2007, praziquantel is also available in a topical combination with the anti-parasite drug emodepside. This combination product is applied to the cat's shoulder area and is effective against the tapeworms of the above types as well as hookworms (Ancylostoma tubaeformae) and roundworms (Toxocara cati). The brand name of this product is Profender® and is available by prescription. Unlike other roundworm/hookworm dewormers, only a single dose is necessary for this product.

Praziquantel is available in non-prescription tablets that may be purchased at pet supply stores. Brand name products, combination products, and injections are available only through veterinarians as they are prescription drugs.

How this Medication Works 

Praziquantel acts by damaging the parasite's skin internally such that the parasite disintegrates and is removed by the host's immune system. Unlike the situation with roundworms, dead tapeworms generally will not be seen passing from the host after deworming.

Side Effects 

Injectable praziquantel tends to sting more than most injections and it is not unusual for a pet to scratch at the site or express discomfort immediately following injection.

The oral form of praziquantel tastes bitter and approximately 5% of patients taking it experience nausea.

It has been reported that approximately one cat in ten will experience weakness, salivation, or nausea after a tapeworm injection with praziquantel, but such reactions have been seen far less frequently. This is generally of minor significance and resolves on its own.

Adult Dipylidium. The segments are easily seen. The thick end is the tail, where segments drop off. Photo by CDC.

Interactions with other Drugs

The following medications can increase the blood levels of praziquantel: cimetidine (an antacid), ketoconazole (an antifungal), and itraconazole (another antifungal).

Cautions and Concerns 

Praziquantel is felt to be safe for use in pregnant patients.

Praziquantel should not be used in puppies under age 4 weeks or kittens under age 6 weeks. The topical Profender product described above is approved for feline use only and is not approved for kittens under age 8 weeks.

Fasting is not necessary prior to praziquantel use and oral praziquantel can be given with or without food.

Tablets should be stored at room temperature away from light exposure.

It is our policy not to give dosing information over the Internet.

Praziquantel (2-cyclohexylcarbonyl-1,2,3,6,7, 11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one, EMBAY 8440, Biltricide) is an anthelminthic drug with activity against all species of schistosomes pathogenic to man and a wide range of cestodes, including the cysticerci of Taenia solium in human tissues and organs, also the CNS. Praziquantel does not reveal any undesired pharmacodynamic effects. After oral administration praziquantel is quantitatively and rapidly absorbed, metabolized and excreted as a variety of metabolites predominantly via the kidneys. The acute toxicity in rats, mice, rabbits and dogs is very low. Rats tolerated by oral administration doses of up to 1000 mg/kg repeated daily for four weeks, and dogs up to 180 mg/kg for 13 weeks without any organ damage. Praziquantel did not disturb reproduction in rats (up to F2-generation), nor did it reveal teratogenic effects in mice, rats and rabbits. In extensive mutagenicity trials performed by different laboratories worldwide, in a variety of test systems, no induction of point mutations, gene conversion, DNA-repair, sister chromatid exchanges (SCEs), or X-linked recessive lethals was detected. Besides, Salmonella tests with urines of praziquantel treated mice, rats, healthy and Schistosoma-infected persons gave no indication of a mutagenic effect. In different in vivo mammalian assays praziquantel not mutagenic either. Low toxicity of praziquantel was not mutagenic either. Low toxicity of praziquantel was demonstrated also in the combined chronic toxicity and carcinogenicity tests which were performed in rats and Syrian hamsters. In none of these species praziquantel exerted a carcinogenic action, and both doses were tolerated.