Carboplatin — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	IV	300 mg/m²	Every 3 weeks	Duration: Typically 4-6 cycles depending on response and toxicity Notes: Dose may be reduced to 250 mg/m² in patients with renal impairment or prior myelosuppressive therapy. Monitor CBC and renal function.
Cat	IV	200-240 mg/m²	Every 3-4 weeks	Duration: Typically 4-6 cycles depending on response and toxicity Notes: Cats are more sensitive to myelosuppression; consider lower starting dose. Monitor CBC and renal function.
Horse	IV	200-300 mg/m²	Every 3 weeks	Duration: Variable; often 3-5 cycles Notes: Use with caution; monitor for myelosuppression and nephrotoxicity.
Cattle	IV	Not established	Not established	Duration: Not established Notes: Not commonly used; extra-label use requires veterinary supervision and withdrawal times.
Small Ruminants	IV	Not established	Not established	Duration: Not established Notes: Not commonly used; extra-label use requires veterinary supervision.
Rabbit	IV	Not established	Not established	Duration: Not established Notes: Not commonly used; limited safety data.
Bird/Poultry	IV	Not established	Not established	Duration: Not established Notes: Not commonly used; limited safety data.
Exotic/Other	IV	Not established	Not established	Duration: Not established Notes: Not commonly used; limited safety data.

Clinical Indications & Species Uses

General Indications

Treatment of various solid tumors and lymphomas in companion animals

Dog (Canine)

Osteosarcoma (adjunct to surgery)
Mammary carcinoma
Oral melanoma
Transitional cell carcinoma of the bladder
Lymphoma (rescue therapy)
Various sarcomas

Cat (Feline)

Mammary carcinoma
Oral squamous cell carcinoma
Lymphoma (rescue therapy)
Fibrosarcoma

Horse (Equine)

Squamous cell carcinoma
Sarcoid (intralesional or systemic)
Lymphoma

Pharmacology & Mechanism of Action

Drug Class: Platinum-containing antineoplastic agent | Pharmacological Group: Alkylating-like agent

Mechanism of Action: Carboplatin is a platinum-based alkylating-like agent that exerts its cytotoxic effects by forming covalent crosslinks with DNA. The platinum atom binds to the N7 position of guanine bases, creating intrastrand and interstrand DNA adducts. This disrupts DNA replication and transcription, leading to cell cycle arrest in the G2 phase and ultimately apoptosis. Carboplatin is less reactive than cisplatin due to the presence of a cyclobutane dicarboxylate leaving group, which results in slower DNA binding and a different toxicity profile.

Pharmacodynamics: Carboplatin exhibits cell cycle phase-nonspecific activity, meaning it kills cancer cells regardless of their position in the cell cycle. It is most effective against rapidly dividing cells. The drug's antitumor activity is dose-dependent, and its efficacy is influenced by the tumor's intrinsic sensitivity and the ability of the cell to repair DNA damage. Carboplatin has shown activity against a variety of solid tumors, including carcinomas, sarcomas, and lymphomas, in veterinary patients.

⚡ Pharmacokinetics Summary

Absorption: Carboplatin is not absorbed orally and must be administered parenterally. After intravenous administration, it is rapidly distributed into total body water.

Distribution: Carboplatin distributes widely into tissues, with highest concentrations in the kidneys, liver, and skin. It does not cross the blood-brain barrier significantly. Protein binding is minimal, approximately 0-10% in dogs and cats.

Metabolism: Carboplatin undergoes minimal hepatic metabolism. The parent compound is the active form, and it is primarily eliminated unchanged by renal excretion.

Excretion: Carboplatin is primarily excreted via the kidneys through glomerular filtration and tubular secretion. In dogs, approximately 70-80% of the administered dose is recovered in urine within 24 hours. In cats, renal excretion is also the main route, but clearance may be slower.

Half-Life: Dog: 1-2 hours (initial), 8-12 hours (terminal); Cat: 1.5-3 hours (initial), 10-15 hours (terminal); Horse: 2-4 hours (terminal).

Bioavailability: Not orally bioavailable; must be given intravenously.

Protein Binding: Minimal (0-10%) in dogs and cats.

Available Formulations & Strengths

Injectable Solution 10 mg/mL in 5 mL, 15 mL, 45 mL, and 60 mL vials (IV)

Lyophilized Powder for Injection 50 mg, 150 mg, 450 mg vials (reconstitute with sterile water or saline) (IV)

Contraindications & Clinical Warnings

Contraindications:

Known hypersensitivity to carboplatin or other platinum compounds
Severe pre-existing myelosuppression (neutropenia, thrombocytopenia)
Severe renal impairment (creatinine clearance < 30 mL/min)
Pregnancy or lactation (teratogenic and embryotoxic)
Active infection (due to immunosuppression)

Warnings & Clinical Precautions:

Carboplatin is a hazardous drug; use appropriate handling and disposal precautions (gloves, gown, eye protection).
Myelosuppression is dose-limiting; monitor complete blood count (CBC) regularly, especially nadir at 10-14 days post-treatment.
Renal function should be assessed before each dose; adjust dose in patients with renal impairment.
Emesis is common; use antiemetics prophylactically (e.g., maropitant, ondansetron).
Extravasation can cause tissue irritation; administer via a secure IV catheter and flush with saline.
Do not use in animals with known hypersensitivity to platinum compounds.
Use with caution in animals with hearing impairment (ototoxicity potential).
In food animals, extra-label use is prohibited or requires extended withdrawal times; consult regulatory guidance.

Adverse Effects & Reactions

Common:

Myelosuppression (neutropenia, thrombocytopenia, anemia)
Nausea and vomiting
Anorexia
Diarrhea
Lethargy

Serious / Severe:

Severe neutropenia with sepsis
Thrombocytopenia with bleeding
Nephrotoxicity (less common than cisplatin)
Ototoxicity (rare)
Anaphylaxis (rare)

Rare:

Hepatotoxicity
Neurotoxicity
Secondary malignancies (long-term use)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Nephrotoxic drugs (e.g., aminoglycosides, amphotericin B, NSAIDs)	Increased risk of nephrotoxicity; avoid concurrent use or monitor renal function closely.	High
Myelosuppressive agents (e.g., other chemotherapy drugs, chloramphenicol)	Additive myelosuppression; reduce doses and monitor CBC frequently.	High
Ototoxic drugs (e.g., aminoglycosides, loop diuretics)	Increased risk of ototoxicity; avoid concurrent use.	Moderate
Live vaccines	Immunosuppression may reduce vaccine efficacy and increase risk of infection; avoid live vaccines during therapy.	Moderate

Overdose & Toxicity Management

Signs of Toxicity:

Severe myelosuppression (neutropenia, thrombocytopenia, anemia)
Nausea, vomiting, diarrhea
Nephrotoxicity (increased BUN, creatinine)
Ototoxicity (hearing loss, tinnitus)
Seizures (rare)

Emergency Treatment Protocol: There is no specific antidote for carboplatin overdose. Treatment is supportive and symptomatic. Hospitalize the patient, provide IV fluids to maintain hydration and promote renal excretion. Administer antiemetics (e.g., maropitant, ondansetron) for vomiting. Monitor CBC and serum biochemistry closely. If severe neutropenia develops, consider granulocyte colony-stimulating factor (G-CSF) and broad-spectrum antibiotics. In cases of severe thrombocytopenia, platelet transfusions may be necessary. For nephrotoxicity, manage with fluid diuresis and supportive care. Consider referral to a veterinary oncologist.

Food Animal Withdrawal Times

Carboplatin is not approved for use in food animals. Extra-label use in food animals is prohibited or requires extended withdrawal times. Consult regulatory authorities (e.g., FDA, EMA) for specific guidance. In the US, carboplatin is not permitted for use in food-producing animals due to its carcinogenic and genotoxic potential.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature (20-25°C; 68-77°F). Protect from light.

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

Handling & Special Conditions: Do not freeze. Reconstituted solutions are stable for 24 hours at room temperature or 48 hours under refrigeration. Discard unused portions.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; approved for human use (e.g., Paraplatin).

Extra-Label (Off-Label) Use: Carboplatin is not FDA-approved for veterinary use but is commonly used extra-label in companion animals under the Animal Medicinal Drug Use Clarification Act (AMDUCA). Extra-label use in food animals is prohibited or requires a valid veterinary-client-patient relationship and extended withdrawal times. It is a hazardous drug and must be handled with caution.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Carboplatin is a valuable chemotherapeutic agent in veterinary oncology, particularly for the treatment of osteosarcoma in dogs, where it is often used as an adjunct to amputation or limb-sparing surgery. It is also used for various carcinomas and sarcomas. Compared to cisplatin, carboplatin has a more favorable safety profile, with less nephrotoxicity and emesis, but it is more myelosuppressive. Dosing is based on body surface area (mg/m²), and careful monitoring of CBC and renal function is essential. Premedication with antiemetics is recommended. In cats, lower doses are used due to increased sensitivity to myelosuppression. Carboplatin should be administered by a veterinarian experienced in chemotherapy, and appropriate safety precautions should be taken to protect personnel. Prognosis depends on tumor type, stage, and response to therapy. Always consider the animal's quality of life and owner's ability to manage potential adverse effects.

References & Literature

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