Piperazine

Anthelmintic Piperazine derivatives

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 45-65 mg/kg Single dose, repeated in 2-3 weeks if needed Duration: One day
Notes: Administer on an empty stomach for optimal absorption.
Cat PO 45-65 mg/kg Single dose, repeated in 2-3 weeks if needed Duration: One day
Notes: May be given with food if vomiting occurs.
Horse PO 100-200 mg/kg Single dose Duration: One day
Notes: For Parascaris equorum; use in foals and young horses.
Cattle PO 100-200 mg/kg Single dose Duration: One day
Notes: For Neoascaris vitulorum in calves.
Sheep/Goat PO 100-200 mg/kg Single dose Duration: One day
Notes: For ascarid infections.
Rabbit PO 100-200 mg/kg Single dose, repeat in 10-14 days Duration: One day
Notes: For Passalurus ambiguus.
Poultry PO (in water or feed) 100-200 mg/kg Single dose, repeat in 2 weeks Duration: One day
Notes: For Ascaridia galli; administer in drinking water or feed.

Clinical Indications & Species Uses

General Indications
  • Treatment of roundworm infections caused by susceptible ascarid species
Dog (Canine)
  • Treatment of ascarid infections (Toxocara canis, Toxascaris leonina)
Cat (Feline)
  • Treatment of ascarid infections (Toxocara cati, Toxascaris leonina)
Horse (Equine)
  • Treatment of ascarid infections (Parascaris equorum)
Cattle (Bovine)
  • Treatment of ascarid infections (Neoascaris vitulorum) in calves
Small Ruminants (Sheep / Goat)
  • Treatment of ascarid infections (e.g., Ascaris ovis) in sheep and goats
Rabbit & Small Mammals
  • Treatment of ascarid infections (e.g., Passalurus ambiguus)
Avian & Poultry
  • Treatment of ascarid infections (e.g., Ascaridia galli) in poultry
Exotic & Other Species
  • Treatment of ascarid infections in various exotic species (e.g., reptiles, rodents)

Pharmacology & Mechanism of Action

Drug Class: Anthelmintic | Pharmacological Group: Piperazine derivatives

Mechanism of Action: Piperazine acts as a GABA (gamma-aminobutyric acid) receptor agonist in nematodes, causing hyperpolarization of the muscle membrane and flaccid paralysis of the parasite. The paralyzed worms are then expelled by normal peristalsis of the host's intestinal tract. It is primarily effective against adult ascarids (roundworms) and has limited efficacy against larval stages or other nematode species.

Pharmacodynamics: Piperazine exhibits a narrow spectrum of activity, mainly against Ascaris spp. and Toxocara spp. in various species. It is not effective against hookworms, whipworms, or tapeworms. The drug's action is reversible, and paralyzed worms may recover if not expelled. It has a wide margin of safety in most species due to its selective action on parasite GABA receptors, which differ from mammalian receptors.

⚑ Pharmacokinetics Summary

Absorption: Piperazine is well absorbed from the gastrointestinal tract after oral administration. Absorption may be influenced by the presence of food, but generally, it is rapid.
Distribution: Piperazine is widely distributed in body tissues and fluids. It crosses the placenta and is excreted in milk. It does not accumulate significantly in tissues.
Metabolism: Piperazine is partially metabolized in the liver, but a significant portion is excreted unchanged in the urine.
Excretion: Piperazine is primarily excreted by the kidneys via glomerular filtration and tubular secretion. In ruminants, some metabolism may occur in the rumen.
Half-Life: The half-life in dogs is approximately 2-4 hours; in other species, it is similar, with rapid elimination.
Bioavailability: Oral bioavailability is high, estimated at 70-80% in monogastric animals.
Protein Binding: Piperazine has low protein binding, approximately 10-20%.

Available Formulations & Strengths

Oral Powder Various (e.g., 50%, 100%) (PO)
Oral Solution Various (e.g., 100 mg/mL) (PO)
Oral Tablet Various (e.g., 250 mg, 500 mg) (PO)
Feed Premix Various (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to piperazine
  • Hepatic or renal impairment (use with caution)
  • Debilitated animals
  • Concurrent use with other anthelmintics that cause spastic paralysis (e.g., pyrantel, levamisole) due to antagonistic mechanisms
Warnings & Clinical Precautions:
  • Not effective against migrating larval stages; repeat treatment may be necessary.
  • Use with caution in pregnant animals; safety has not been fully established, but generally considered safe.
  • In horses, piperazine may cause transient ataxia or colic in some individuals.
  • In poultry, ensure adequate water intake to avoid toxicity.
  • Do not use in animals with intestinal obstruction.
  • Avoid use in animals with severe malnutrition.

Adverse Effects & Reactions

Common:

  • Vomiting
  • Diarrhea
  • Anorexia
  • Transient ataxia (in horses)

Serious / Severe:

  • Neurotoxicity (tremors, seizures) at high doses
  • Hepatotoxicity (rare)
  • Nephrotoxicity (rare)

Rare:

  • Allergic reactions (urticaria, angioedema)
  • Hemolytic anemia (in G6PD-deficient animals)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Pyrantel pamoate Antagonistic mechanism (pyrantel causes spastic paralysis, piperazine causes flaccid paralysis); concurrent use may reduce efficacy. Moderate
Levamisole Antagonistic mechanism; concurrent use may reduce efficacy. Moderate
Phenothiazine Increased risk of toxicity (hepatic and hematologic). High
Neuromuscular blocking agents Potential additive effects on neuromuscular blockade. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Ataxia
  • Muscle tremors
  • Seizures
  • Respiratory depression
  • Coma

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 intravenous fluids, electrolyte replacement, and anticonvulsants (e.g., diazepam) if seizures occur. Monitor respiratory and cardiac function.

Food Animal Withdrawal Times

πŸ₯© Meat: 14 daysπŸ₯› Milk: 3 daysπŸ₯š Eggs: 7 days

Withdrawal times may vary by country and formulation; follow local regulations. For cattle, sheep, goats, and poultry, observe withdrawal periods for meat, milk, and eggs.

Storage, Handling & Regulatory Information

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

Handling & Special Conditions: Keep container tightly closed. Protect from moisture. Store in a dry place.

Dispensing Status: Over-The-Counter (OTC)

Approval Status: Approved for use in dogs, cats, horses, cattle, sheep, goats, and poultry in various formulations.

Extra-Label (Off-Label) Use: In the US, piperazine is available over-the-counter for veterinary use. Extra-label use in food animals requires a veterinary prescription and must comply with AMDUCA regulations, including extended withdrawal times.

Clinical Pearls & Practice Notes

πŸ’‘ Clinical Insights: Piperazine is an older anthelmintic that is still used for treating roundworm infections in many species. It is safe and effective when used appropriately, but its narrow spectrum limits its use. It is often used in young animals for ascarid control. Because it is not effective against migrating larvae, repeat treatments are often necessary. It is generally well tolerated, but care should be taken in debilitated animals. In food animals, observe withdrawal times. Piperazine is inexpensive and may be a cost-effective option for ascarid control in some settings.

References & Literature

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