(chloramphenicol palmitate [limited availability],  chloramphenicol sodium succinate)

Brands

Viceton, Chloramphenicol, Chloramphenicol Sodium Succinate

Availability

• Tablets: 100 mg, 250 mg, 500 mg
• Capsules: 250 mg
• Chloramphenicol Sodium Succinate injectable: 1 gram vial (100 mg/mL)
• Chloramphenicol also available in oral suspension, otic and ophthalmic preparations

Pharmacology

Chloramphenicol is a broad-spectrum antibiotic that acts as a bacteriostatic, but at higher concentrations can act as a bactericidal. It binds to the 50S ribosomal subunit of susceptible bacteria and prevents bacterial protein synthesis. It has activity against many Gram-negative, Gram-positive, aerobic, and especially anaerobic organisms.

The drug is rapidly absorbed following oral administration and widely distributed throughout the body, including the central nervous system, where it is able to cross the blood-brain barrier. While highest levels are found in the liver and kidney the drug tends to remain at therapeutic levels in most tissues and fluids  ²⁷.

Chloramphenicol has the potential to accumulate at toxic levels in the newborn, and very young, due to the inability to be effectively metabolized and eliminated from the body. It is, therefore, not recommended to be given to very young animals. It is also not recommended to be given in pregnant or lactating animals due to its ability to cross the placenta and to be passed in breast milk.

Chloramphenicol is metabolized in the liver and eliminated by glucuronidation. It is excreted by the kidneys with only a small fraction being excreted unchanged.

Though chloramphenicol is quite effective at getting into the tissues, being able to penetrate pus to get to the bacteria, it has a short half-life which requires more frequent dosing times.

Indications

To treat serious infections due to organisms resistant to other less toxic antibiotics, or when its penetration into the site of infection is clinically superior to other antibiotics.
Those bacteria sensitive to this drug include clostridium, chlamydia, mycoplasma, salmonella.

Drug Interactions or Contraindications

• Chloramphenicol is contraindicated if another drug can be used instead due to its potential to cause bone marrow depression.
• Chloramphenicol, being a Cytochrome P450-CYP2B11 inhibitor may possibly inhibit other CYP enzymes, thereby decreasing clearance of drugs metabolized by the same metabolic enzymes. Because it has the potential to inhibit metabolism of drugs such as opiates, barbiturates, and salicylate it is advised to use caution when giving with Chloramphenicol.¹
• Not recommended for use with Tylan, azithromycin or erythromycin, as they may be antagonistic with chloramphenicol.
• Acetaminophen will elevate chloramphenicol levels.
• Chloramphenicol has the potential to antagonize bactericidal activity of the penicillin’s and aminoglycosides.
• Rifampin may decrease serum chloramphenicol levels.

Adverse Reactions

Avoid using if impaired hepatic or kidney function is present. Prolonged use may result in suprainfections.

EENT: optic neuritis

GI: diarrhea, disturbance of intestinal flora

Hematologic: irreversible idiosyncratic aplastic anemia (identified in humans), dose-related bone marrow suppression with long term therapy (reversible once drug stopped)

Hepatic: jaundice

Other: anaphylaxis, chloramphenicol may falsely elevate urine glucose levels

Dosage Recommendations

Chloramphenicol palmitate: 25-90 mg/lb, PO, q8hrs  ^4, 12

or

Chloramphenicol palmitate: 50 mg/kg to 200 mg/kg, PO, q8hrs   ^1, 2

or

Chloramphenicol sodium succinate: 15 mg/lb to 25 mg/lb, SQ or IM, BID for 7-14 days   ^4, 12

or

Chloramphenicol sodium succinate: 20 mg/kg to 50 mg/kg, SQ, q6hr to q12hr  ²⁷

or

Chloramphenicol sodium succinate: 30mg/kg to 50mg/kg, PO, SQ, IM, q8hr to q12hr   ^1, 11, 35

or

30 mg/kg to 50 mg/kg, PO, q8hr to q12hr   ^{41,  43,  44}

Considerations

• Do not use for trivial infections; can be highly toxic.
• Medication can be very bitter tasting. Mix with something sweet.
• Due to its potential for toxicity avoid inhaling the powder when having to compound or mix this drug and wash hands immediately following direct skin contact. Wearing gloves is advised.
• Store capsules and tablets in tight container, away from light, at room temperature.

References

1. Papich, M. G. (2016). Chloramphenicol. In Saunders Handbook of Veterinary Drugs: Small and Large Animals (4th ed., pp. 148-150). Elsevier. doi:https://doi.org/10.1016/B978-0-323-24485-5.00153-4