Mupirocin — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days, depending on response Notes: Clip hair and clean area before application. Avoid contact with eyes. Use with Elizabethan collar if licking is a concern.
Cat	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Cats may groom; use caution and consider protective collar.
Horse	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Clean area before application. May require bandaging.
Cattle	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Not commonly used; consider other approved topical antibiotics.
Small Ruminants	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Not commonly used; consider other approved topical antibiotics.
Rabbit	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Prevent ingestion; use Elizabethan collar if needed.
Bird/Poultry	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Not commonly used; ensure feathers are dry before application.
Exotic/Other	Topical	Apply thin layer to affected area	2-3 times daily	Duration: 5-14 days Notes: Use with caution in small mammals; prevent ingestion.

Clinical Indications & Species Uses

General Indications

Topical treatment of bacterial skin infections caused by susceptible Gram-positive organisms, especially staphylococci and streptococci

Dog (Canine)

Treatment of pyoderma (superficial and deep) caused by Staphylococcus pseudintermedius
Treatment of impetigo
Treatment of infected wounds and abrasions
Treatment of interdigital furunculosis (as adjunctive therapy)

Cat (Feline)

Treatment of pyoderma (especially superficial)
Treatment of infected wounds and abscesses (topical adjunct)
Treatment of feline acne (secondary infection)

Horse (Equine)

Treatment of superficial skin infections (e.g., bacterial dermatitis, infected wounds)

Rabbit & Small Mammals

Treatment of skin infections (e.g., bacterial dermatitis, abscesses) as topical adjunct

Exotic & Other Species

Treatment of skin infections in small mammals (e.g., guinea pigs, rats) and reptiles (e.g., scale rot) as topical adjunct

Pharmacology & Mechanism of Action

Drug Class: Antibacterial | Pharmacological Group: Monoxycarbolic acid derivative

Mechanism of Action: Mupirocin inhibits bacterial protein synthesis by reversibly binding to bacterial isoleucyl-tRNA synthetase, preventing the incorporation of isoleucine into protein chains. This action is bacteriostatic at low concentrations and bactericidal at high concentrations. It is highly active against staphylococci and streptococci, including methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus pseudintermedius (MRSP).

Pharmacodynamics: Mupirocin exhibits time-dependent killing and has a post-antibiotic effect. Its activity is pH-dependent, with optimal activity at acidic pH. It is primarily effective against Gram-positive organisms, with limited activity against Gram-negative bacteria and anaerobes. Resistance can develop via mutation of the target enzyme or acquisition of plasmid-mediated mupA gene.

⚡ Pharmacokinetics Summary

Absorption: Systemic absorption after topical application is minimal. When applied to intact skin, less than 0.3% is absorbed. Absorption may increase when applied to broken skin or mucous membranes.

Distribution: Systemic distribution is negligible due to poor absorption. When absorbed, it is rapidly metabolized and distributed, but this is not clinically relevant.

Metabolism: Mupirocin is rapidly metabolized in the skin and systemically to the inactive metabolite monic acid A.

Excretion: Any absorbed drug is excreted primarily in the urine as the inactive metabolite. Fecal excretion is minimal.

Half-Life: Systemic half-life is approximately 20-40 minutes, but this is not clinically relevant due to minimal absorption.

Bioavailability: Systemic bioavailability is negligible after topical application (<0.3%).

Protein Binding: Protein binding is approximately 95% when absorbed, but this is not clinically significant.

Available Formulations & Strengths

Topical Ointment 2% (20 mg/g) (Topical)

Topical Cream 2% (20 mg/g) (Topical)

Contraindications & Clinical Warnings

Contraindications:

Known hypersensitivity to mupirocin or any component of the formulation
Use in eyes (ophthalmic formulations are not available; use only ophthalmic-specific products)
Use on large areas of broken skin or in patients with renal impairment (due to potential absorption of polyethylene glycol vehicle)

Warnings & Clinical Precautions:

For topical use only; avoid contact with eyes, nose, and mouth.
Do not use in large quantities on open wounds or burns, especially in patients with renal dysfunction, due to potential absorption of the vehicle (polyethylene glycol).
Prolonged use may result in overgrowth of non-susceptible organisms, including fungi.
Use with caution in animals with a history of allergic reactions to antibiotics.
In food animals, observe withdrawal times and follow label directions.
Keep out of reach of children and animals.

Adverse Effects & Reactions

Common:

Local irritation
Redness
Stinging or burning sensation at application site

Serious / Severe:

Allergic contact dermatitis
Systemic absorption leading to renal toxicity (rare, with large area application)

Rare:

Superinfection with resistant organisms
Anaphylaxis (extremely rare)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Chloramphenicol	May antagonize the antibacterial effect of mupirocin; avoid concurrent use.	Moderate
Other topical antibiotics (e.g., neomycin, bacitracin)	No significant interactions; may be used in combination if needed.	Mild
Systemic aminoglycosides	No significant interaction; but monitor renal function if large areas are treated.	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Local irritation
Excessive licking or grooming
Gastrointestinal upset if ingested (e.g., vomiting, diarrhea)

Emergency Treatment Protocol: If ingested, provide supportive care. Induce vomiting only if large amounts were ingested and within a short time. Administer activated charcoal to reduce absorption. Monitor for signs of systemic toxicity. For topical overdose, wash off with soap and water. No specific antidote.

Food Animal Withdrawal Times

🥩 Meat: 0 days🥛 Milk: 0 days🥚 Eggs: 0 days

Mupirocin is not approved for food animals; however, due to minimal systemic absorption, withdrawal times are generally not required. Check local regulations. For extra-label use in food animals, consult a veterinarian and follow appropriate withdrawal periods.

Storage, Handling & Regulatory Information

Storage Temperature: Store at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C and 30°C (59°F and 86°F).

Handling & Special Conditions: Keep tightly closed. Do not freeze. Keep away from excessive heat.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; approved for human use as topical antibiotic.

Extra-Label (Off-Label) Use: In the US, mupirocin is not FDA-approved for veterinary use, but it can be used extra-label under AMDUCA (Animal Medicinal Drug Use Clarification Act) by or on the order of a veterinarian. For food animals, a valid veterinarian-client-patient relationship is required, and withdrawal times must be established.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Mupirocin is a valuable topical antibiotic for treating superficial bacterial skin infections, particularly those caused by staphylococci, including MRSA and MRSP. It is often used in small animals for pyoderma and wound infections. Because of its unique mechanism of action, it is useful for infections resistant to other antibiotics. However, it should be reserved for cases where other topical antibiotics are ineffective or inappropriate to minimize resistance development. In veterinary practice, it is commonly used off-label. Always clean and dry the affected area before application. Use an Elizabethan collar to prevent licking and ingestion. Monitor for local irritation. For deep or systemic infections, systemic antibiotics are required. In food animals, use is rare and should be done with caution, adhering to withdrawal times.

References & Literature

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