The mechanism of action of praziquantel involves interaction with schistosome calcium ion channels. It is thought to increase the permeability of the parasite's cell membrane to calcium ions, leading to muscle contraction, spasm, and paralysis. This paralysis causes the worms to detach from the host tissues and be expelled from the body. The compound also damages the parasite's tegument, making it more susceptible to host immune attack. Schistosome calcium ion channels are currently the only known target of praziquantel.

In vitro, praziquantel is effective against a range of parasitic flatworms, causing muscle contraction and tegumental damage. Its activity is assessed by measuring the motility of parasites in culture and by evaluating tegumental damage using electron microscopy. The compound's anthelmintic activity is concentration-dependent, with higher concentrations leading to more rapid paralysis and death of the parasites. Specific IC50 values for different parasite species are not detailed in the provided search results.

In vivo, praziquantel is used for the treatment of schistosomiasis and other trematode and cestode infections in humans and animals. It is the drug of choice for most schistosome infections. The compound is administered orally and is well absorbed. It is effective as a single dose or short course of treatment. The compound's efficacy has been demonstrated in numerous clinical studies, and it is included on the World Health Organization's List of Essential Medicines.

The in vitro activity of praziquantel is assessed using parasite motility assays. Schistosomes or other parasitic flatworms are collected from infected animals and maintained in culture medium. Various concentrations of praziquantel are added to the culture, and the motility of the parasites is assessed under a microscope. The compound's effect on parasite muscle contraction can be assessed by measuring changes in muscle tension using force transducers. The damage to the parasite tegument can be assessed by electron microscopy or by measuring the release of tegumental proteins.

For cellular assays, parasite cells or tissues are used to study the effects of praziquantel on calcium ion channels and muscle contraction. Parasites are treated with various concentrations of praziquantel, and changes in intracellular calcium levels are measured using calcium-sensitive fluorescent dyes (e.g., Fluo-4). The effect on muscle contraction can be assessed by measuring changes in muscle tension. The expression of calcium channel genes is analyzed by qPCR.

In vivo, praziquantel is administered orally to patients or animal models. In clinical settings, the recommended dose for schistosomiasis is 40-60 mg/kg as a single dose or divided into two doses. For tapeworm infections, the dose is typically 10-25 mg/kg. Efficacy is assessed by examining stool or urine samples for parasite eggs at various time points after treatment. In animal models, the compound is administered at various doses, and the reduction in worm burden is assessed at necropsy.

Absorption, Distribution and Excretion
Following oral administration of praziquantel, approximately 80% of the dose is absorbed. In subjects with normal liver function, the mean ± standard deviation (Cmax) and AUC after fasting administration of 40 mg/kg praziquantel were 0.83 ± 0.52 µg/mL and 3.02 ± 0.59 µg/mL·hr, respectively. The time to peak concentration (Tmax) was 1.48 ± 0.74 hours. Approximately 80% of oral praziquantel is excreted via the kidneys, with almost all (greater than 99%) excreted as praziquantel metabolites. The estimated volume of distribution after a single oral administration of 40 mg/kg praziquantel in healthy volunteers was 7695 ± 2716 L. The estimated clearance after a single oral administration of 40 mg/kg praziquantel in healthy volunteers was 11.4 ± 2.8 L/kg/h.

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Metabolism/Metabolites
Praziquantel is rapidly metabolized by the cytochrome P450 enzyme system and exhibits a first-pass effect after oral administration.

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Biological Half-Life
When administered orally, the elimination half-life of praziquantel in serum is 0.8 to 1.5 hours.
Praziquantel has a molecular weight of 312.41 g/mol and a molecular formula of C19H24N2O2. It is a white to off-white crystalline powder that is practically insoluble in water but soluble in organic solvents. The compound should be stored at room temperature in a tightly closed container, protected from light. Specific pharmacokinetic parameters include an oral bioavailability of approximately 80%, a half-life of 1-3 hours, and extensive first-pass metabolism.

Hepatotoxicity
Praziquantel treatment is associated with elevated serum transaminase levels in up to 27% of patients, but these abnormalities usually resolve spontaneously. Praziquantel rarely causes clinically significant liver injury, usually accompanied by hypersensitivity reactions such as rash and fever. In a large retrospective study in China, jaundice was reported in 2 out of 25,000 patients treated with praziquantel, but specific details of these two cases were not provided. Studies on long-term praziquantel treatment are scarce, and most controlled trials of this drug used a one-day course without monitoring serum transaminase levels. However, in schistosomiasis-endemic areas of China, millions have received praziquantel treatment as part of a large-scale control strategy. Praziquantel prophylactic treatment combined with snail control has significantly reduced infection rates in the population without significant toxicity. Therefore, systemic hypersensitivity reactions caused by praziquantel may be accompanied by mild acute liver injury, but the allergic reaction and liver injury are usually short-lived and resolve rapidly even without specific treatment. Probability Score: D (Possibly a rare cause of clinically significant liver injury, usually part of a systemic hypersensitivity reaction).

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Effects during pregnancy and lactation
◉ Overview of use during lactation
Because the amount of praziquantel in breast milk is extremely low, the amount ingested by the infant is very small, and no adverse effects are expected on breastfed infants. Experts believe that lactation should not be a contraindication for mothers taking praziquantel. To minimize infant exposure, a single dose can be taken before the infant's longest sleep period, or within 24 hours after a single dose or the last dose of a series of doses, using an alternative feeding method (e.g., stored breast milk).
◉ Effects on breastfed infants
As of the revision date, no relevant published information was found.
◉ Effects on lactation and breast milk
As of the revision date, no relevant published information was found.

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Protein binding
Approximately 80% of praziquantel binds only to albumin.
Praziquantel is generally well-tolerated. Common side effects include headache, dizziness, gastrointestinal disturbances (nausea, vomiting, abdominal pain), and transient increases in liver enzymes. These side effects are usually mild and self-limiting. The compound is contraindicated in patients with a history of hypersensitivity to praziquantel and in patients with ocular cysticercosis (due to the risk of inflammatory reactions). Comprehensive toxicological studies are required to establish its full safety profile.

Internal Med. 1983, 99:195-198.

2-[cyclohexyl(oxo)methyl]-3,6,7,11b-tetrahydro-1H-pyrazino[2,1-a]isoquinoline-4-one is an isoquinoline compound. Praziquantel is a pyrazinoisoquinoline derivative of the thiamethoxam class of compounds, used as a broad-spectrum anthelmintic. Specifically, it is used to treat trematode and tapeworm infections such as schistosomiasis, tapeworm infection, and cysticercosis. Praziquantel's efficacy and low cost in treating flatworm infections (the cost of treating one child is approximately US$0.20) have made it an important component of the World Health Organization's 2030 plan to eliminate schistosomiasis. Although its exact mechanism of action has not been fully elucidated since its approval in 1980, praziquantel is an anthelmintic. Praziquantel is an effective anthelmintic against a variety of trematodes and tapeworms, primarily used to treat schistosomiasis, liver fluke infection, and cysticercosis. Praziquantel treatment has been reported to cause elevated serum transaminase levels, but even clinically significant liver damage is extremely rare. Praziquantel is a pyrazinoquinoline derivative with anthelmintic properties. It increases the permeability of the epidermis of susceptible worms, leading to an influx and increase of calcium ions into the epidermis, which in turn causes elevated calcium levels in the sarcoplasmic reticulum, ultimately resulting in rapid muscle contraction and paralysis of the worm. Furthermore, vacuolization and blistering of the epidermal syncytiosomes occur, leading to epidermal disintegration, antigen exposure, and triggering a host defense response against the worm. This ultimately results in granuloma formation and promotes phagocytosis. Praziquantel is an anthelmintic used to treat most schistosomiasis and many tapeworm infections. See also: Praziquantel; Praziquantel (ingredient); Emodipine; Praziquantel (ingredient); Eplerenone; Praziquantel (ingredient)... See more...

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Drug Indications
Praziquantel is indicated for the treatment of schistosomiasis caused by all genus Schistosoma (e.g., Schistosoma mekongiensis, Schistosoma japonicum, Schistosoma mansoni, and Schistosoma haematobium) in patients aged 1 year and older, as well as liver fluke disease and liver fluke infection caused by Clonorchis sinensis/Clonorchis thaliana (approval for this indication is based on studies that do not differentiate between these two flukes).
FDA Label

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Mechanism of Action
While the exact mechanism of action is not fully understood, it is speculated that praziquantel targets the β subunit of voltage-gated Ca_sub>2+ channels, particularly in Schistosoma mansoni and Schistosoma japonicum, because... these subunits lack two conserved serine residues. This conclusion is supported by the following findings: concomitant administration of calcium channel blockers such as nicarpicone and nifedipine can induce resistance to praziquantel in 50% of Schistosoma mansoni. Furthermore, increased exposure to surface antigens was observed, but little is known about its mechanism of action.

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Pharmacodynamics
In vitro studies have shown that praziquantel induces rapid contraction of Schistosoma mansoni by specifically affecting cell membrane permeability. The drug also causes vacuolation and disintegration of the Schistosoma mansoni epidermis. This effect is more pronounced in adults than in larvae. Increased Ca2+ influx may play an important role. Secondary effects include inhibition of glucose uptake, reduction of glycogen levels, and stimulation of lactate release. Praziquantel is specifically effective against flukes and tapeworms; it is ineffective against nematodes (including filarial worms). Praziquantel is effective against schistosome infections (e.g., Schistosoma mekongiensis, Schistosoma japonicum, Schistosoma mansoni, and Schistosoma haematobium) and liver fluke infections (Clonorhizoma sinensis/Clonorhizoma thamnoides). Published in vitro data suggest that praziquantel may be ineffective against migrating schistosome larvae. A unique characteristic of praziquantel is its relatively poor efficacy against juvenile schistosomes. While initially effective, its efficacy against schistosomes gradually decreases, reaching its lowest point after 3-4 weeks. Subsequently, efficacy increases again, returning to full effectiveness after 6-7 weeks.
Praziquantel is a widely used anthelmintic drug that is included on the World Health Organization's List of Essential Medicines. It is the drug of choice for the treatment of schistosomiasis and is also effective against a range of other trematode and cestode infections. Praziquantel is available as a generic medication and is used in mass drug administration programs for the control of schistosomiasis. Its development has had a major impact on the treatment of parasitic diseases worldwide.

C19H24N2O2

312.41

312.183

C, 73.05; H, 7.74; N, 8.97; O, 10.24

55268-74-1

Praziquantel-d11;1246343-36-1

4891

Solid powder

1.2±0.1 g/cm3

544.1±50.0 °C at 760 mmHg

136-142ºC

254.6±22.5 °C

0.0±1.5 mmHg at 25°C

1.615

2.44

0

2

1

23

472

0

O=C1CN(C(C2CCCCC2)=O)CC3N1CCC4=C3C=CC=C4

FSVJFNAIGNNGKK-UHFFFAOYSA-N

InChI=1S/C19H24N2O2/c22-18-13-20(19(23)15-7-2-1-3-8-15)12-17-16-9-5-4-6-14(16)10-11-21(17)18/h4-6,9,15,17H,1-3,7-8,10-13H2

2-(cyclohexanecarbonyl)-3,6,7,11b-tetrahydro-1H-pyrazino[2,1-a]isoquinolin-4-one

Droncit Biltricide Praziquantel

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~50 mg/mL (~160.05 mM)
H2O : ~0.1 mg/mL (~0.32 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (8.00 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (8.00 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (8.00 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 12.5 mg/mL (40.01 mM) in 50% PEG300 50% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication (<60°C).
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)