PRAZIQUANTEL
Clinical safety rating: safe
Animal studies have demonstrated safety
Praziquantel increases the permeability of schistosome cell membranes to calcium ions, causing severe contraction and paralysis of the worm musculature, leading to dislodgment and death.
| Metabolism | Extensively metabolized in the liver by cytochrome P450 enzymes (CYP3A4) to inactive metabolites; undergoes first-pass metabolism. |
| Excretion | Primarily renal: approximately 80% of metabolites excreted in urine (unchanged drug <0.1%); fecal excretion accounts for about 15%. |
| Half-life | Terminal elimination half-life is 1-1.5 hours for praziquantel; 4-6 hours for its main metabolite (4-hydroxypraziquantel). Half-life prolonged in patients with severe hepatic impairment. |
| Protein binding | Primarily bound to albumin: approximately 80-85% bound. |
| Volume of Distribution | Vd approximately 1-2 L/kg, indicating extensive distribution into tissues. |
| Bioavailability | Oral bioavailability is about 80% (range 60-100%), but can be significantly increased by co-administration with food or grapefruit juice. |
| Onset of Action | Oral: Onset within 1-2 hours post-dose; peak plasma concentration at 1-3 hours. |
| Duration of Action | Duration of clinical effect is 24 hours after a single oral dose, but treatment typically requires one day of multiple doses (e.g., 3 doses in one day) for optimal efficacy. |
| Molecular Weight | 312.41 |
20 mg/kg orally three times daily for 1 day for schistosomiasis; 25 mg/kg orally three times daily for 1 day for clonorchiasis and opisthorchiasis; 5-10 mg/kg orally single dose for taeniasis; 15-25 mg/kg orally single dose for hymenolepiasis; 25 mg/kg orally three times daily for 1 day for paragonimiasis, fasciolopsiasis, and heterophyiasis.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment necessary for mild to moderate renal impairment. For severe renal impairment (GFR <30 mL/min), use with caution; consider dose reduction or extended interval due to potential accumulation, although specific guidelines are lacking. Hemodialysis: no supplemental dose needed. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose by 50% or extend interval. Child-Pugh Class C: contraindicated or use with extreme caution; if used, consider further dose reduction and monitor for adverse effects. |
| Pediatric use | Children ≥1 year: same weight-based dosing as adults. For schistosomiasis: 20 mg/kg/dose three times daily for 1 day. For clonorchiasis/opisthorchiasis: 25 mg/kg/dose three times daily for 1 day. For taeniasis: 5-10 mg/kg single dose. For hymenolepiasis: 15-25 mg/kg single dose. For paragonimiasis, fasciolopsiasis, heterophyiasis: 25 mg/kg/dose three times daily for 1 day. Maximum single dose: 2.4 g per day. |
| Geriatric use |
| 1st trimester | Limited human data; animal studies show fetotoxicity at high doses. Use only if benefit outweighs risk. |
| 2nd trimester | No known teratogenicity; can be used if clinically indicated. |
| 3rd trimester | Generally considered safe; short-term use for parasitic infections acceptable. |
Clinical note
CYP450 inducers like carbamazepine can decrease levels Can cause abdominal discomfort and dizziness.
| Placental transfer | Crosses placenta in animal studies; human data limited but suggests transfer. |
| Breastfeeding | Excreted into breast milk in low concentrations; unlikely to cause adverse effects in infants. Consider benefit of treating maternal infection. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Common Effects | other fluke infections |
| Serious Effects |
Hypersensitivity to praziquantel or any componentOcular cysticercosis (may cause irreversible damage)
| Precautions | Use with caution in patients with hepatic impairment; may cause dizziness, drowsiness, and abdominal discomfort; avoid driving or operating machinery until effects are known. For neurocysticercosis, concomitant corticosteroids are recommended to reduce inflammatory response. Not recommended for ocular cysticercosis due to risk of irreversible damage. |
| Food/Dietary | Take with a meal or milk to enhance absorption. Grapefruit may increase drug levels by inhibiting CYP3A4; avoid grapefruit products. No significant restriction with other foods. |
Loading safety data…
| No specific dose adjustment required in elderly patients based on age alone. Use standard adult dosing. Monitor for adverse effects due to potential age-related comorbidities and polypharmacy. Consider renal and hepatic function. |
| L2 (Probably Compatible) |
| Teratogenic Risk | Praziquantel is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal harm, but no adequate human studies exist. First trimester exposure: theoretical risk; avoid unless necessary. Second and third trimesters: considered safe when indicated for treatment of parasitic infections outweighing risks. |
| Fetal Monitoring | Monitor for maternal adverse effects: dizziness, headache, abdominal pain. No specific fetal monitoring required, but obstetric ultrasound may be considered if exposure occurs during first trimester. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Human data limited; no significant impact reported. |
| Clinical Pearls | Administer with food to increase bioavailability and reduce nausea. Crush tablets for patients with difficulty swallowing. Monitor for cardiac arrhythmias in patients with pre-existing cardiac disease, especially at high doses. Use cautiously in patients with hepatic impairment due to extensive first-pass metabolism. Contraindicated in ocular cysticercosis due to inflammatory reaction risk. Obtain eosinophil count and stool ova/parasite exams 1-3 months post-treatment to confirm cure. |
| Patient Advice | Take with food to reduce side effects and improve absorption. · Tablets can be crushed and mixed with food if needed. · Avoid alcohol during treatment and for at least 24 hours after the last dose to prevent increased side effects. · Dizziness and drowsiness are common; avoid driving or operating machinery until you know how the drug affects you. · Complete the full course even if symptoms improve. · Report any severe headache, vision changes, or seizures immediately. · Praziquantel may cause temporary increases in liver enzymes; notify your doctor if you notice jaundice or dark urine. |