Pronunciation praz-i-KWAN-tel AHFS/Drugs.com Monograph CAS ID 55268-74-1 | Trade names Biltricide MedlinePlus a608048 | |
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Pregnancycategory AU: B1US: B (No risk in non-human studies) Routes ofadministration Human use: by mouth (tablets) | ||
Praziquantel, sold under the brandname Biltricide among others, is a medication used to treat a number of types of parasitic worm infections. Specifically it is used for schistosomiasis, clonorchiasis, opisthorchiasis, tapeworm infections, cysticercosis, hydatid disease, and other fluke infections. It should not be used for cysticercosis that involves the eye. It is taken by mouth.
Contents
- Milbemax milbemycin oxime praziquantel
- Medical uses
- Side effects
- Pregnancy
- Drug interactions
- Mechanism of action
- Pharmacokinetics
- History
- Brand names
- Regulatory approval
- Veterinary medicine
- References
Side effects 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 worm's sucker.
Praziquantel was approved for medical use in the United States in 1982. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about 0.4 to 18.15 USD per day. In the United States a typical course of treatment costs 100 to 200 USD.
Milbemax milbemycin oxime praziquantel
Medical uses
Praziquantel is used to treat diseases caused by infection with several types of internal/gastrointestinal, and external parasites, including:
Side effects
The majority of side effects develop due to the release of the contents of the parasites as they are killed and the consequent host immune reaction. The heavier the parasite burden, the heavier and more frequent the side effects normally are.
Pregnancy
Animal studies have failed to reveal evidence of fetal harm. There are no controlled data in human pregnancy. Praziquantel should be used during pregnancy only if clearly needed; caution is recommended.
Drug interactions
The antibiotic rifampicin decreases plasma concentrations of praziquantel.
Carbamazepine and phenytoin are reported to reduce the bioavailability of praziquantel.
Chloroquine reduces the bioavailability of praziquantel.
The drug cimetidine heightens praziquantel bioavailability.
Mechanism of action
The mode of action is not exactly known at present, but experimental evidence indicates praziquantel increases the permeability of the membranes of schistosome cells towards calcium ions. The drug thereby induces contraction of the parasites, resulting in paralysis in the contracted state. The dying parasites are dislodged from their site of action in the host organism and may enter systemic circulation or may be destroyed by host immune reaction (phagocytosis). Additional mechanisms including focal disintegrations and disturbances of oviposition (laying of eggs) are seen in other types of sensitive parasites.
Another hypothesis concerning the mechanism of action of praziquantel has been recently reported. The drug seems to interfere with adenosine uptake in cultured worms. This effect may have therapeutical relevance given that the schistosome, as the Taenia and the Echinococcus (other praziquantel-sensitive parasites), is unable to synthesize purines such as adenosine de novo.
Bayer's Animal Health Division website states, "Praziquantel is active against cestodes (tapeworms). Praziquantel is absorbed, metabolized in the liver, and excreted in the bile. Upon entering the digestive tract from the bile, cestocidal activity is exhibited. Following exposure to praziquantel, the tapeworm loses its ability to resist digestion by the mammalian host. Because of this, whole tapeworms, including the scolices (plural of "scolex"), are very rarely passed after administration of praziquantel. In many instances, only disintegrated and partially digested pieces of tapeworms will be seen in the stool. The majority of tapeworms are digested and are not found in the feces."
Praziquantel is administered as a racemate, but only the (R)-enantiomer is biologically active; the enantiomers may be separated using a resolution of an amine obtained from praziquantel.
Pharmacokinetics
Praziquantel is well absorbed (about 80%) from the gastrointestinal tract. However, due to extensive first-pass metabolism, only a relatively small amount enters systemic circulation. Praziquantel has a serum half-life of 0.8 to 1.5 hours in adults with normal renal and liver function. Metabolites have a half-life of 4 to 5 hours. In patients with significantly impaired liver function (Child-Pugh score B and C), the serum half-life is increased to 3 to 8 hours. Praziquantel and its metabolites are mainly excreted renally; within 24 h after a single oral dose, 70 to 80% is found in urine, but less than 0.1% as the unchanged drug. Praziquantel is metabolized through the cytochrome P450 pathway via CYP3A4. Agents that induce or inhibit CYP3A4 such as phenytoin, rifampin, and azole antifungals will affect the metabolism of praziquantel.
Praziquantel has a particularly dramatic effect on patients with schistosomiasis. Studies of those treated have shown that within six months of receiving a dose of praziquantel, up to 90% of the damage done to internal organs due to schistosomiasis infection can be reversed.
History
Praziquantel was developed in the laboratories for parasitological research of Bayer AG and Merck KGaA in Germany (Elberfeld and Darmstadt) in the mid 1970s.
Brand names
Regulatory approval
Praziquantel is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system.
Praziquantel is not licensed for use in humans in the UK but it can be imported when necessary on a named patient basis. It is available in the UK as a veterinary anthelmintic.
Praziquantel is FDA approved in the US for the treatment of schistosomiasis and liver fluke, although it is effective in other infections.
Veterinary medicine
It may cause problems in dogs with MDR1 mutations.