Lincomycin Hydrochloride

Lincosamide antibiotic Antibacterial

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 15-25 mg/kg q12h Duration: 5-7 days or as directed
Notes: Administer on an empty stomach to enhance absorption.
Dog IM 10-20 mg/kg q12h Duration: 5-7 days
Notes: May cause pain at injection site.
Cat PO 15-25 mg/kg q12h Duration: 5-7 days
Notes: Use with caution in cats due to potential GI upset.
Horse PO 10-20 mg/kg q12h Duration: 5-7 days
Notes: Oral administration may cause diarrhea; monitor closely.
Cattle IM 10 mg/kg q24h Duration: 3-5 days
Notes: Not for use in lactating dairy cows if milk withdrawal is a concern.
Swine PO 10 mg/kg q12h Duration: 3-5 days
Notes: Commonly used in feed or water.
Rabbit PO 10-20 mg/kg q12h Duration: 5-7 days
Notes: Monitor for GI stasis; use with caution.
Poultry PO (water) 20 mg/kg q24h Duration: 3-5 days
Notes: Ensure adequate water intake.

Clinical Indications & Species Uses

General Indications
  • Treatment of infections caused by susceptible Gram-positive bacteria, anaerobes, and Mycoplasma.
Dog (Canine)
  • Treatment of skin infections, wound infections, abscesses, and osteomyelitis caused by susceptible Gram-positive organisms and anaerobes.
Cat (Feline)
  • Treatment of skin infections, wound infections, and abscesses caused by susceptible organisms.
Horse (Equine)
  • Treatment of respiratory tract infections, skin infections, and bone infections caused by susceptible organisms.
Cattle (Bovine)
  • Treatment of pneumonia, foot rot, and other infections caused by susceptible organisms.
Small Ruminants (Sheep / Goat)
  • Treatment of pneumonia, mastitis, and other infections caused by susceptible organisms.
Rabbit & Small Mammals
  • Treatment of infections caused by susceptible Gram-positive bacteria and anaerobes.
Avian & Poultry
  • Treatment of necrotic enteritis and other infections caused by susceptible organisms.
Exotic & Other Species
  • Treatment of infections in reptiles and small mammals caused by susceptible organisms.

Pharmacology & Mechanism of Action

Drug Class: Lincosamide antibiotic | Pharmacological Group: Antibacterial

Mechanism of Action: Lincomycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, specifically to the 23S rRNA, thereby preventing peptide bond formation and elongation. It is primarily bacteriostatic, but may be bactericidal at higher concentrations. It has activity against Gram-positive bacteria, anaerobes, and some Mycoplasma species.

Pharmacodynamics: Lincomycin exhibits time-dependent killing and has a post-antibiotic effect. It is effective against susceptible organisms such as Staphylococcus spp., Streptococcus spp., and anaerobes like Bacteroides and Fusobacterium. It is not effective against Gram-negative aerobes. Resistance can occur via methylation of the ribosomal target or efflux pumps.

⚡ Pharmacokinetics Summary

Absorption: Lincomycin is rapidly absorbed after oral administration in monogastric animals, but bioavailability may be variable. In ruminants, oral absorption is poor due to ruminal degradation. Intramuscular and subcutaneous injections result in rapid absorption.
Distribution: Lincomycin is widely distributed into body tissues and fluids, including bone, synovial fluid, and peritoneal fluid. It crosses the placenta and is excreted in milk. It does not penetrate the blood-brain barrier significantly.
Metabolism: Lincomycin is metabolized in the liver to inactive metabolites.
Excretion: Excretion is primarily via bile and feces, with a smaller amount excreted in urine. In ruminants, significant biliary excretion occurs.
Half-Life: Dog: ~4-5 hours; Cat: ~4-5 hours; Horse: ~8-10 hours; Cattle: ~4-6 hours; Swine: ~6-8 hours.
Bioavailability: Oral: ~20-50% in monogastrics; IM: ~90%.
Protein Binding: Approximately 70-80% protein-bound in most species.

Available Formulations & Strengths

Oral Tablet 100 mg, 200 mg, 500 mg (PO)
Oral Solution 50 mg/mL (PO)
Injectable Solution 100 mg/mL, 300 mg/mL (IM, SC, IV (slow))
Feed Premix Various concentrations (PO (feed))

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to lincomycin or clindamycin
  • Rabbits, hamsters, guinea pigs, and other small herbivores (risk of fatal enteritis)
  • Horses (oral administration may cause severe diarrhea)
  • Known history of gastrointestinal disease
  • Use in animals with severe renal or hepatic impairment (caution)
Warnings & Clinical Precautions:
  • Use with caution in animals with a history of colitis or other GI disorders.
  • May cause superinfection with resistant organisms.
  • In ruminants, oral administration is not recommended due to ruminal degradation and potential dysbiosis.
  • Prolonged use may result in bacterial or fungal overgrowth.
  • Use in lactating dairy animals requires careful consideration of withdrawal times.
  • In horses, parenteral administration may be associated with clostridial enterocolitis; use only if no alternative.
  • Avoid rapid IV administration to prevent cardiovascular collapse.

Adverse Effects & Reactions

Common:

  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Injection site pain or swelling

Serious / Severe:

  • Clostridial enterocolitis (especially in horses)
  • Pseudomembranous colitis
  • Anaphylaxis
  • Hepatotoxicity
  • Neuromuscular blockade (with high doses)

Rare:

  • Blood dyscrasias
  • Skin reactions
  • Esophageal irritation

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Erythromycin May antagonize the antibacterial effect of lincomycin due to competition for the same ribosomal binding site. Moderate
Chloramphenicol May antagonize the antibacterial effect of lincomycin. Moderate
Neuromuscular blocking agents May enhance neuromuscular blockade, leading to respiratory depression. High
Kaolin-pectin May reduce oral absorption of lincomycin. Mild
Opioid analgesics May cause additive respiratory depression. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Ataxia
  • Muscle weakness
  • Respiratory depression
  • Seizures (in severe cases)

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Induce emesis if recent oral ingestion and animal is conscious. Administer activated charcoal to reduce absorption. Provide IV fluids for dehydration and electrolyte imbalances. Monitor respiratory and cardiac function. In severe cases, consider mechanical ventilation.

Food Animal Withdrawal Times

🥩 Meat: 6 days🥛 Milk: 4 days

Withdrawal times vary by country and formulation. For cattle, meat withdrawal is 6 days; milk withdrawal is 4 days. For swine, meat withdrawal is 6 days. For poultry, meat withdrawal is 5 days; eggs are not applicable for broilers. Always follow local regulations.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), excursions permitted between 15-30°C (59-86°F).

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

Handling & Special Conditions: Protect from light and moisture. Keep container tightly closed. Do not freeze injectable solutions.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs, cats, swine, and poultry in the US. Not approved for use in cattle, horses, or other species; extra-label use is permitted under AMDUCA.

Extra-Label (Off-Label) Use: Extra-label use in food animals requires a valid veterinary-client-patient relationship and must comply with AMDUCA regulations. Extended withdrawal times may be necessary.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Lincomycin is a valuable antibiotic for treating infections caused by Gram-positive bacteria and anaerobes, particularly in skin, bone, and respiratory infections. However, its use in horses and small herbivores is limited due to the risk of severe enterocolitis. In food animals, strict adherence to withdrawal times is essential. Oral administration in ruminants is ineffective due to ruminal degradation. Always perform culture and sensitivity testing when possible to ensure susceptibility. Monitor for adverse effects, especially diarrhea, and discontinue if severe GI signs occur.

References & Literature

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