Serum levels of amoxycillin following its oral administration to thoroughbred foals.

The research article reports on a study testing the effects of oral amoxycillin on thoroughbred foals, indicating only some types of bacteria are effectively treated by the medication.

Study Approach

• The researchers administered Amoxycillin trihydrate orally to six foals at three different dose rates: 13 mg/kg (low), 20 mg/kg (medium), and 30 mg/kg (high). They then checked the serum concentrations in the foals at intervals up to eight hours.
• The aim was to examine the duration for which therapeutic serum levels (1 microgram/ml and 2 micrograms/ml) persisted at each dose rate.
• The team also analyzed the minimum inhibitory concentrations of amoxycillin against eight types of common pathogens (bacteria) found in foals.

Outcomes of the Study

• Results showed that a therapeutic serum level of 1 microgram/ml persisted for 268 minutes at a dose rate of 13 mg/kg, for 339 minutes at 20 mg/kg, and for 381 minutes at 30mg/kg.
• A serum level of 2 micrograms/ml persisted for 198 minutes at a dose rate of 13 mg/kg, for 268 minutes at 20 mg/kg, and for 311 minutes at 30 mg/kg.

Drug Efficacy Against Different Bacteria

• Of the bacteria tested, only Streptococcus equi, Strep zooepidemicus, and Staphylococcus aureus (non-beta lactamase producing) would have been effectively treated by the amoxycillin serum levels in the foals.

Conclusions

• Based on the findings, the authors concluded that amoxycillin is not suitable for broad spectrum use against pathogens in foals as it was effective against just a few types of bacteria.
• However, because of its ease of administration orally, amoxycillin still has a useful role in treating Streptococcal and Staphylococcal infections that aren’t caused by beta lactamase producers.
• The authors suggest that, with the use of sensitivity testing, the drug might also be useful for treating some infections caused by the Gram-negative organisms Actinobacillus equuli and Salmonella typhimurium.