Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is used to treat schistosomiasis, clonorchiasis, opisthorchiasis, tapeworm infections, cysticercosis, hydatid disease, and other fluke infections. It should not be used for worm infections of the eye. It is taken by mouth.Side effects in humans may include poor coordination, abdominal pain, vomiting, headache, and allergic reactions. While it may be used during pregnancy, it is not recommended for use during breastfeeding. Praziquantel is in the anthelmintic class of medications. It works partly by affecting the function of the worms sucker.Praziquantel was approved for medical use in the United States in 1982. It is on the World Health Organizations List of Essential Medicines. Medical uses
Praziquantel is used to treat diseases caused by infection with several types of internal/gastrointestinal, and external parasites, including:

Hydatid disease caused by infection of various organs with larval stages of tapeworms of the genus Echinococcus
Cysticercosis caused by infection of the brain and/or muscles with the eggs and larvae of the pork tapeworm Taenia solium (though it has been judged less effective than albendazole in treatment of neurocysticercosis)
In dogs and cats, whose gastrointestinal tracts are infected with the tapeworms Dipylidium caninum or Taenia taeniaeformis, respectively; praziquantel is also often used in fixed combination with pyrantel embonate against the roundworms (ascarids): Toxocara cati and Toxascaris leonina. Praziquantel is also effective against Echinococcus multilocularis.
No substance of medical value was discovered, however, until 1903 when two German scientists working at Bayer, Emil Fischer and Joseph von Mering, discovered that barbital was very effective in putting dogs to sleep. Barbital was then marketed by Bayer under the trade name Veronal. It is said that Mering proposed this name because the most peaceful place he knew was the Italian city of Verona.It was not until the 1950s that the behavioral disturbances and physical dependence potential of barbiturates became recognized.Barbituric acid itself does not have any direct effect on the central nervous system and chemists have derived over 2,500 compounds from it that possess pharmacologically active qualities. The broad class of barbiturates is further broken down and classified according to speed of onset and duration of action. Ultrashort-acting barbiturates are commonly used for anesthesia because their extremely short duration of action allows for greater control. These properties allow doctors to rapidly put a patient "under" in emergency surgery situations. Doctors can also bring a patient out of anesthesia just as quickly, should complications arise during surgery. The middle two classes of barbiturates are often combined under the title "short/intermediate-acting." These barbiturates are also employed for anesthetic purposes, and are also sometimes prescribed for anxiety or insomnia. This is not a common practice anymore, however, owing to the dangers of long-term use of barbiturates; they have been replaced by the benzodiazepines and Z-drugs such as zolpidem, zaleplon and eszopiclone for sleep.