Effect of changes in urine pH on plasma pharmacokinetic variables of ampicillin sodium in horses.

This research investigates the impact of urine pH on how ampicillin sodium, an antibiotic, behaves in a horse’s bloodstream. The study concluded that changes in urine pH, within a range commonly seen in healthy horses, probably do not significantly affect the pharmacokinetics of intravenous ampicillin sodium.

Methodology

• The study involved administering a single dose of ampicillin sodium (10mg/kg of body weight) intravenously to Thoroughbred horses. The horses had either alkaline (pH greater than 8.0) or acidic (pH less than 4.5) urine.
• The urine’s alkalinity was raised and maintained by orally giving the horses up to 400mg of sodium bicarbonate per kilogram of body weight daily. On the other hand, the acidity of urine was achieved and maintained via oral administration of up to 400mg of ammonium chloride per kilogram of body weight daily.
• The amount of ampicillin sodium in the horse’s plasma was measured using an agar diffusion microbiological assay, with Bacillus subtilis – a type of bacteria – as the test organism.

Key Findings

• The plasma disposition kinetics, or the way ampicillin sodium behaved in the horse’s bloodstream, was best described as a two-exponential decay pattern.
• There weren’t any statistically significant variations spotted in the half-life of the drug (the time it takes for the concentration of the drug to be halved), the area under the plasma concentration-time curve (an important pharmacokinetic measurement), the volume of distribution (the theoretical volume that would be necessary to contain the total amount of an administered drug), or the rate of clearance from the body between horses with alkaline or acidic urine.
• The researchers concluded that alterations in urine pH within the range seen in clinically healthy horses are unlikely to influence the plasma pharmacokinetic attributes of intravenously administered ampicillin sodium.

Implications and Conclusion

• The study suggests that pH alterations in a horse’s urine, whether it becomes more alkaline or acidic within the typical range for a healthy horse, may not affect how ampicillin sodium behaves in the horse’s bloodstream after it’s been administered intravenously.
• It’s important to note that these results apply only to healthy horses, and further investigation would be needed to determine if disease conditions or other factors could affect the pharmacokinetics of ampicillin sodium in this species.