Praziquantel

Uses

Praziquantel is an anthelmintic medication used to treat a number of parasitic worm infections such as schistosomiasis.

For the treatment of infections due to all species of schistosoma.

Praziquantel is also used to associated treatment for these conditions: Cestode infections, Cysticercosis, Liver fluke infection, Trematode infections, Schistosoma infection

How Praziquantel works

Praziquantel works by causing severe spasms and paralysis of the worms' muscles. This paralysis is accompanied - and probably caused - by a rapid Ca 2+ influx inside the schistosome. Morphological alterations are another early effect of praziquantel. These morphological alterations are accompanied by an increased exposure of schistosome antigens at the parasite surface. The worms are then either completely destroyed in the intestine or passed in the stool. An interesting quirk of praziquantel is that it is relatively ineffective against juvenile schistosomes. While initially effective, effectiveness against schistosomes decreases until it reaches a minimum at 3-4 weeks. Effectiveness then increases again until it is once again fully effective at 6-7 weeks. Glutathione S-transferase (GST), an essential detoxification enzyme in parasitic helminths, is a major vaccine target and a drug target against schistosomiasis. Schistosome calcium ion channels are currently the only known target of praziquantel.

Food Interaction

• Avoid grapefruit products.
• Take with food.

[Moderate] ADJUST DOSING INTERVAL: Administration with food increases the oral bioavailability of praziquantel.

The mechanism has not been described.

In nine healthy volunteers, administration of praziquantel (1800 mg single oral dose) following a high-fat meal increased the mean praziquantel peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by 243% and 180%, respectively, compared to administration under fasting conditions.

Administration with a high-carbohydrate meal increased these values by 515% and 271%, respectively, compared to fasting.

Overall, the relative bioavailability was increased by a factor of 2.72 and 3.98 with the high-fat and high-carbohydrate meals, respectively.

The time to reach peak concentration (Tmax) and elimination half-life (T1<2) were not significantly altered.

Coadministration with grapefruit juice may increase the oral bioavailability of praziquantel.

The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruit.

In 18 healthy volunteers, administration of praziquantel (1800 mg single oral dose) with 250 mL of commercially squeezed grapefruit juice resulted in increases in the mean praziquantel Cmax and AUC of 63% and 90%, respectively, compared to administration with water.

The Tmax and T1<2 were not significantly altered.

The pharmacokinetics of praziquantel were subject to a high degree of interpatient variability with and without grapefruit juice.

MANAGEMENT: To ensure maximal oral absorption, praziquantel should be administered with meals.

Administration with grapefruit juice may further increase pharmacologic effects of praziquantel, including adverse effects such dizziness, abdominal discomfort, and nausea.

Praziquantel Drug Interaction

Moderate: dexamethasoneUnknown: aspirin, amoxicillin / clavulanate, azithromycin, sulfamethoxazole / trimethoprim, diphenhydramine, dextran, low molecular weight, fluconazole, glipizide, arginine, levothyroxine, acetaminophen, procaine penicillin, valproic acid, multivitamin, thiamine, cyanocobalamin, pyridoxine, ascorbic acid, phytonadione

Praziquantel Disease Interaction

Major: cysticercosis, epilepsyModerate: arrhythmias, liver impairment

Elimination Route

Rapidly absorbed (80%)

Half Life

0.8-1.5 hours (in serum)

Innovators Monograph

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