Epsiprantel

Anthelmintic Praziquantel analog (pyrazinoisoquinoline derivative)

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 5.5 mg/kg Single dose Duration: One time
Notes: Administer on an empty stomach for optimal efficacy. May be given with food if vomiting occurs.
Cat PO 2.5 mg/kg Single dose Duration: One time
Notes: Administer on an empty stomach. Repeat in 2-3 weeks if reinfection is suspected.

Clinical Indications & Species Uses

General Indications
  • Treatment of cestode infections in dogs and cats
Dog (Canine)
  • Treatment of tapeworm infections caused by Dipylidium caninum, Taenia pisiformis, and Echinococcus granulosus
Cat (Feline)
  • Treatment of tapeworm infections caused by Dipylidium caninum and Taenia taeniaeformis

Pharmacology & Mechanism of Action

Drug Class: Anthelmintic | Pharmacological Group: Praziquantel analog (pyrazinoisoquinoline derivative)

Mechanism of Action: Epsiprantel is a pyrazinoisoquinoline anthelmintic that acts by increasing the permeability of the parasite's cell membrane to calcium ions. This leads to rapid influx of calcium, causing intense muscular contraction and paralysis of the tapeworm, followed by vacuolization and disruption of the tegument. The damaged parasite is then dislodged from the intestinal wall and digested by host enzymes or expelled in feces. The drug is highly specific for cestodes and has minimal activity against nematodes.

Pharmacodynamics: Epsiprantel exhibits potent cestocidal activity against adult tapeworms, particularly Dipylidium caninum and Taenia species. It is effective against both immature and mature stages of these parasites. The drug's action is rapid, with visible effects on the parasite within minutes of exposure. It has a wide margin of safety in target species, with no significant effects on mammalian cells due to differences in calcium channel physiology.

⚡ Pharmacokinetics Summary

Absorption: Epsiprantel is poorly absorbed from the gastrointestinal tract after oral administration. The majority of the drug remains in the intestinal lumen, where it exerts its local anthelmintic effect. Systemic absorption is minimal, with peak plasma concentrations being very low.
Distribution: Due to poor absorption, systemic distribution is limited. The small amount that is absorbed is widely distributed in tissues, but concentrations are negligible. It does not significantly cross the blood-brain barrier.
Metabolism: The absorbed fraction is rapidly metabolized in the liver to inactive metabolites. The primary metabolic pathway involves hydroxylation and conjugation.
Excretion: The drug and its metabolites are primarily excreted in the feces via bile, with a small amount excreted in urine. In dogs, approximately 90% of the administered dose is recovered in feces within 48 hours.
Half-Life: The elimination half-life in dogs is approximately 1-2 hours for the absorbed fraction, but the drug's action is primarily local in the gut.
Bioavailability: Oral bioavailability is very low (<5%) due to poor absorption and extensive first-pass metabolism.
Protein Binding: Protein binding is not well characterized due to low systemic exposure; it is presumed to be moderate.

Available Formulations & Strengths

Oral Tablet 12.5 mg, 25 mg, 50 mg (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to epsiprantel or any component of the formulation
  • Use in puppies or kittens less than 7 weeks of age (safety not established)
  • Concurrent use with other anthelmintics unless directed by a veterinarian
Warnings & Clinical Precautions:
  • Use with caution in animals with hepatic or renal impairment, although systemic exposure is minimal.
  • Not for use in food-producing animals.
  • Keep out of reach of children and pets.
  • Wash hands after administration.
  • In case of accidental ingestion by humans, seek medical attention.
  • Pregnant or lactating animals: safety not fully established; use only if clearly needed.

Adverse Effects & Reactions

Common:

  • Mild and transient vomiting
  • Diarrhea
  • Loss of appetite

Serious / Severe:

  • Allergic reactions (rare)
  • Neurological signs (very rare, at high doses)

Rare:

  • Hypersensitivity reactions
  • Ataxia
  • Seizures (at extremely high doses)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Praziquantel Additive cestocidal effects; may increase risk of adverse effects if used concurrently. Moderate
Arecoline Potential for increased cholinergic effects; not recommended. Moderate
Cimetidine May increase systemic absorption of epsiprantel, but clinical significance is low. Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Excessive salivation
  • Depression
  • Ataxia
  • Tremors

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Induce emesis if recent ingestion and animal is conscious. Administer activated charcoal to reduce absorption. Provide fluid therapy and monitor for electrolyte imbalances. In severe cases, anticonvulsants may be needed for seizures.

Food Animal Withdrawal Times

Not approved for use in food-producing animals. Do not use in animals intended for human consumption.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F)

Handling & Special Conditions: Protect from moisture. Keep container tightly closed.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs and cats in the US (e.g., Cestex®).

Extra-Label (Off-Label) Use: In the US, epsiprantel is approved for use in dogs and cats. Extra-label use in other species is permitted under AMDUCA only with a valid veterinarian-client-patient relationship and must comply with withdrawal time requirements if used in food animals (though not recommended).

Clinical Pearls & Practice Notes

💡 Clinical Insights: Epsiprantel is a highly effective and safe cestocide for dogs and cats. It is particularly useful for treating Dipylidium caninum infections, which are commonly acquired from fleas. Because it is poorly absorbed, it has a wide margin of safety and is well tolerated. It is important to treat the underlying flea infestation to prevent reinfection. For Echinococcus infections, strict hygiene measures should be followed due to zoonotic potential. Dosage should be based on accurate body weight. In cases of heavy tapeworm burden, repeated dosing may be necessary. Epsiprantel is often combined with other anthelmintics to provide broad-spectrum coverage, but combination products should be used according to label directions.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)