Clarithromycin
Clarithromycin is a semisynthetic macrolide antibacterial with substantial tissue and intracellular distribution. Its major equine application is combination treatment of Rhodococcus equi infection in foals. In small animals, it is used less commonly for selected susceptible infections, including some atypical mycobacterial infections and Helicobacter-associated disease.
Group
Macrolide antibacterial
Mechanism of Action
Clarithromycin binds to the 50S bacterial ribosomal subunit and interferes with translocation and elongation of the nascent peptide chain. Inhibition of protein synthesis generally produces a bacteriostatic effect, with bactericidal activity possible against some highly susceptible organisms. Accumulation in cells and respiratory tissues supports its activity against intracellular pathogens such as Rhodococcus equi and selected mycobacteria.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Susceptible bacterial infection | 7.5 mg/kg | PO | Every 12 h | |
| Bacterial infections | 2.5–10 mg/kg | PO | Every 12 h | |
| Bacterial infections | 5–10 mg/kg | PO | Every 12 h | |
| Canine leproid granuloma combination treatment | Reference only | PO | Clarithromycin 15–25 mg/kg TOTAL DAILY orally divided every 8–12 hours plus rifampin 10–15 mg/kg orally daily, usually for 4–8 weeks until lesions substantially regress or resolve. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Susceptible bacterial infection | 7.5 mg/kg | PO | Every 12 h | |
| Feline leprosy combination treatment | Reference only | PO | Use two or three agents selected from clarithromycin 62.5 mg per cat every 12 hours, clofazimine 25–50 mg daily or 50 mg every other day, and rifampin 10–15 mg/kg daily. Maintain a diagnosis-specific specialist combination plan. | |
| Nocardia nova combination treatment | Reference only | PO | Amoxicillin 20 mg/kg orally every 12 hours with clarithromycin 62.5–125 mg per cat orally every 12 hours and/or doxycycline at least 5 mg/kg every 12 hours. The doxycycline lower-bound statement is not an invented bounded range. | |
| Helicobacter combination treatment | Reference only | PO | Clarithromycin 7.5 mg/kg, metronidazole 10–15 mg/kg and amoxicillin 20 mg/kg, each orally every 12 hours for 14 days. | |
| Historical mycobacterial combination treatment | Reference only | PO | An older M. bovis protocol combines clarithromycin 5–10 mg/kg every 12 hours, rifampin 10–20 mg/kg daily and enrofloxacin 5–10 mg/kg every 12–24 hours for at least two months, then two drugs for four additional months. This is a zoonotic-disease and combination-management issue, not a routine calculator regimen; feline enrofloxacin exposure also requires separate safety review. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Rhodococcus equi infection | 7.5 mg/kg | PO | Every 12 h | Foals only. Often combined with rifampin 10 mg/kg orally every 12 hours. |
Pigs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Susceptible bacterial infection | 7.5 mg/kg | PO | Every 12 h |
Ferrets
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Helicobacter mustelae treatment | Reference only | PO | Clarithromycin 12.5 mg/kg orally every 12 hours with ranitidine bismuth citrate 24 mg/kg every 12 hours for 14 days; another report uses eight-hour intervals. Product availability and exact bismuth salt differ from subsalicylate. | |
| Alternative Helicobacter treatment | Reference only | PO | Clarithromycin 12.5–50 mg/kg every 8–24 hours with omeprazole 0.7 mg/kg orally daily; the route for clarithromycin is not independently assigned in this bullet. |
Indications
- Treatment of Rhodococcus equi pneumonia and associated susceptible infections in foals, generally in combination with rifampin.
- Combination treatment of selected atypical mycobacterial infections in dogs and cats.
- Treatment of selected Helicobacter-associated gastric disease in cats or ferrets as part of a combination regimen.
- Treatment of selected susceptible respiratory, skin or soft-tissue infections in small animals.
Contraindications
- Use cautiously in adult horses, ruminants, rodents and rabbits because of enteritis risk.
- Pregnancy requires caution.
Interactions
- CYP inhibition can increase concentrations of other medicines, including cyclosporine.
- Rifampin can markedly reduce clarithromycin exposure despite their established combination use.
Adverse effects
- Nausea
- Soft stools or diarrhea
- Severe enteritis in susceptible species
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Clarithromycin 250 mg tablet | Tablet | 250 mg / tablet | PO |
| Clarithromycin 500 mg tablet | Tablet | 500 mg / tablet | PO |
| Clarithromycin 25 mg/mL oral liquid | Oral Liquid | 25 mg / mL | PO |
| Clarithromycin 50 mg/mL oral liquid | Oral Liquid | 50 mg / mL | PO |
| Claritek 250 mg tablet Getz Pharma (Pvt.) Limited | Tablet | 250 mg / tablet | PO |
| Claritek 500 mg tablet Getz Pharma (Pvt.) Limited | Tablet | 500 mg / tablet | PO |
| Claritek suspension 125 mg/5 mL Getz Pharma (Pvt.) Limited Final reconstituted strength. Store below 30°C; use within 14 days at room temperature. | Oral Liquid | 125 mg / 5 mL | PO |
| Claritek suspension 250 mg/5 mL Getz Pharma (Pvt.) Limited Final reconstituted strength. Store below 30°C; use within 14 days at room temperature. | Oral Liquid | 250 mg / 5 mL | PO |
Monitoring and Administration
Monitor fecal consistency and discontinue for severe diarrhea. Evaluate susceptibility and response.
For foal Rhodococcus treatment the described concurrent rifampin regimen is 10 mg/kg orally every 12 hours. Do not treat the clarithromycin dose as a complete stand-alone protocol.
Tablets may be dispersed in water for immediate administration; long-term compounded stability is not established.
For foal Rhodococcus treatment, another rifampin partner regimen is 5 mg/kg orally every 12 hours or 10 mg/kg every 24 hours. Do not merge partner doses from different protocols.
Keep reconstituted conventional oral suspension at room temperature and discard after 14 days; do not refrigerate that preparation.