Imidocarb Dipropionate — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	IM or SC	6.6 mg/kg (for Babesia canis)	Single dose, may repeat in 2 weeks	Duration: Single dose or two doses 14 days apart Notes: For Babesia gibsoni, higher doses (7.5 mg/kg) may be needed. Administer deep IM to reduce pain.
Cat	IM or SC	5 mg/kg	Single dose, may repeat in 72 hours	Duration: One to two doses Notes: Off-label use; monitor for adverse effects.
Horse	IM	2.2 mg/kg (for Theileria equi)	Single dose, may repeat in 24 hours	Duration: One to two doses Notes: For Babesia caballi, 2.2 mg/kg once. For Theileria equi, some protocols use 4 mg/kg divided into two doses.
Cattle	IM or SC	1.2-3 mg/kg	Single dose, may repeat in 2 weeks	Duration: One to two doses Notes: For Babesia bovis, 1.2 mg/kg; for Babesia bigemina, 2.5 mg/kg; for Anaplasma, 3 mg/kg. Do not exceed 3 mg/kg.
Sheep and Goats	IM or SC	1.2-2.4 mg/kg	Single dose, may repeat in 24 hours	Duration: One to two doses Notes: Use lower dose for Babesia ovis; higher for Babesia motasi.

Clinical Indications & Species Uses

General Indications

Treatment of babesiosis and theileriosis in various species
Prophylaxis of babesiosis in endemic areas

Dog (Canine)

Treatment of Babesia canis and Babesia gibsoni infections
Treatment of Ehrlichia canis (as an adjunct)
Treatment of Cytauxzoon felis (off-label)

Cat (Feline)

Treatment of Cytauxzoon felis (off-label)
Treatment of Babesia felis (off-label)

Horse (Equine)

Treatment of Babesia caballi and Theileria equi infections
Treatment of equine piroplasmosis

Cattle (Bovine)

Treatment of Babesia bovis, Babesia bigemina, and Babesia divergens infections
Treatment of Anaplasma marginale (as an adjunct)
Treatment of Theileria parva (East Coast fever)

Small Ruminants (Sheep / Goat)

Treatment of Babesia ovis and Babesia motasi infections in sheep and goats

Exotic & Other Species

Treatment of babesiosis in zoo animals (e.g., antelope, giraffe) (off-label)

Pharmacology & Mechanism of Action

Drug Class: Antiprotozoal | Pharmacological Group: Carbanilide derivative

Mechanism of Action: Imidocarb dipropionate is a carbanilide derivative that exerts its antiprotozoal effect by interfering with the polyamine metabolism of susceptible organisms. It inhibits the uptake of inositol and the synthesis of nucleic acids in protozoa, leading to disruption of cellular replication. Additionally, it may affect the parasite's energy metabolism by inhibiting the production of ATP. The drug is particularly effective against Babesia and Theileria species, where it acts both as a babesiacide and a theileriacide, with a rapid onset of action.

Pharmacodynamics: Imidocarb dipropionate has a broad-spectrum antiprotozoal activity, primarily against intraerythrocytic parasites such as Babesia spp. and Theileria spp. It is also effective against some other protozoa like Anaplasma marginale (though not a protozoan, it is often grouped). The drug is both a babesiacide and a theileriacide, and it has been shown to have immunomodulatory effects, potentially enhancing the host's immune response. Its efficacy is dose-dependent, and it is often used for both treatment and prophylaxis of babesiosis. The drug does not have significant antibacterial or antiviral activity.

⚡ Pharmacokinetics Summary

Absorption: Imidocarb dipropionate is poorly absorbed after oral administration; therefore, it is administered parenterally (IM or SC). After intramuscular injection, absorption is rapid, with peak plasma concentrations achieved within 30 minutes to 2 hours. The drug is well absorbed from the injection site.

Distribution: Imidocarb is widely distributed throughout the body, with high concentrations found in the liver, kidneys, and lungs. It crosses the placenta and is excreted in milk. It has a large volume of distribution, indicating extensive tissue binding. The drug accumulates in erythrocytes, which is important for its activity against intraerythrocytic parasites.

Metabolism: Imidocarb is metabolized in the liver, primarily by hydroxylation and conjugation. The metabolites are less active than the parent compound. The metabolism is species-dependent, with some species metabolizing the drug more rapidly than others.

Excretion: Excretion is primarily via the kidneys, with both the parent drug and its metabolites eliminated in the urine. A significant portion is also excreted in the feces via biliary excretion. The elimination half-life is long, allowing for prolonged therapeutic effects. In cattle, the half-life is approximately 7-10 days, while in dogs it is shorter, around 4-6 days.

Half-Life: Cattle: 7-10 days; Dogs: 4-6 days; Horses: approximately 5-7 days

Bioavailability: Oral bioavailability is low (<10%) due to poor absorption; parenteral administration results in near-complete bioavailability.

Protein Binding: Imidocarb is moderately protein-bound, with approximately 50-60% bound to plasma proteins.

Available Formulations & Strengths

Injectable Solution 12% solution (120 mg/mL) (IM or SC)

Injectable Solution 10% solution (100 mg/mL) (IM or SC)

Contraindications & Clinical Warnings

Contraindications:

Known hypersensitivity to imidocarb or other carbanilide derivatives
Do not use in animals with severe hepatic or renal impairment
Do not use in pregnant animals unless the benefit outweighs the risk (potential embryotoxic effects)
Do not use in lactating animals if milk is intended for human consumption (withdrawal period required)
Do not use in animals with cholinesterase deficiency (risk of prolonged anticholinesterase effects)

Warnings & Clinical Precautions:

Imidocarb has anticholinesterase activity; use with caution in animals with myasthenia gravis or those receiving other anticholinesterase drugs
May cause severe pain at injection site; administer deep IM and consider dividing doses
Use with caution in debilitated or geriatric animals
In food animals, observe withdrawal times; extra-label use requires veterinary oversight
Avoid accidental self-injection; imidocarb is toxic to humans
In horses, use with caution in breeding animals; may affect fertility
Monitor for signs of organophosphate toxicity (salivation, lacrimation, urination, defecation, muscle tremors)

Adverse Effects & Reactions

Common:

Pain at injection site
Salivation
Lacrimation
Transient diarrhea
Vomiting (in dogs)
Local swelling at injection site

Serious / Severe:

Severe cholinergic crisis (muscle tremors, respiratory distress)
Hepatotoxicity
Nephrotoxicity
Cardiac arrhythmias
Anaphylaxis
Pulmonary edema (in cattle)

Rare:

Bone marrow suppression
Neurotoxicity
Teratogenic effects
Death (in overdose)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Organophosphates and other anticholinesterase agents	Additive anticholinesterase activity, leading to increased risk of cholinergic toxicity	High
Succinylcholine and other depolarizing neuromuscular blockers	Prolonged neuromuscular blockade due to anticholinesterase activity	High
Aminoglycoside antibiotics	Potential for increased nephrotoxicity	Moderate
Corticosteroids	May reduce the efficacy of imidocarb by immunosuppressive effects	Moderate

Overdose & Toxicity Management

Signs of Toxicity:

Excessive salivation
Lacrimation
Urination
Defecation
Muscle tremors
Ataxia
Respiratory depression
Seizures
Coma
Death

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Administer atropine sulfate at a dose of 0.05-0.1 mg/kg IV to counteract cholinergic effects. Provide respiratory support, fluid therapy, and anticonvulsants if needed. Monitor cardiac and respiratory function closely. In severe cases, consider pralidoxime (2-PAM) for cholinesterase reactivation, but it is not always effective.

Food Animal Withdrawal Times

🥩 Meat: 213 days🥛 Milk: 21 days

Withdrawal times vary by country and formulation. In the US, the withdrawal time for cattle is 213 days for meat and 21 days for milk. In other countries, it may be shorter (e.g., 28 days for meat in some EU countries). Always consult local regulations.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature (20-25°C, excursions permitted to 15-30°C)

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Protect from light. Keep container tightly closed. Do not freeze. Store away from food and feed.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use in the US; available through compounding pharmacies or imported. Approved in other countries for use in cattle, horses, and dogs.

Extra-Label (Off-Label) Use: In the US, imidocarb is not FDA-approved for use in food animals; extra-label use is permitted under AMDUCA with a valid veterinary-client-patient relationship. In some countries, it is approved for use in cattle and horses. Extra-label use in non-food animals is common.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Imidocarb dipropionate is a highly effective antiprotozoal agent primarily used for the treatment of babesiosis and theileriosis in domestic animals. It is particularly valuable in endemic areas where tick-borne diseases are prevalent. The drug has a long duration of action, allowing for single-dose therapy in many cases. However, its use is limited by potential adverse effects, especially cholinergic toxicity, and the need for strict withdrawal times in food animals. In dogs, it is the drug of choice for Babesia canis infections, but resistance has been reported. In horses, it is used for equine piroplasmosis, but treatment may not eliminate the carrier state. In cattle, it is effective against both Babesia and Anaplasma, but it does not provide sterile immunity. Clinical monitoring should include assessment for cholinergic signs, especially in animals with concurrent organophosphate exposure. Due to its potential for tissue irritation, deep intramuscular injection is recommended. In food animals, adherence to withdrawal times is critical to prevent drug residues in meat and milk. Overall, imidocarb remains an essential drug in veterinary parasitology, but its use requires careful consideration of species-specific dosing, adverse effects, and regulatory constraints.

References & Literature

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