Bioavailability of pivampicillin and ampicillin trihydrate administered as an oral paste in horses.

The study investigates the bioavailability of two types of horse medication, pivampicillin and ampicillin trihydrate, given as oral paste. The study shows that pivampicillin provided satisfactory blood concentration in both fed and unfed horses, while ampicillin trihydrate gave minimal blood concentration, making the former a more effective treatment.

Research Methods

• Two types of penicillin-based medications were used: pivampicillin and ampicillin trihydrate. These were administered to horses in the form of an oral paste.
• The experiment involved five horses receiving pivampicillin while three horses were administered ampicillin trihydrate. The former were tested in both starving and fed conditions, but the latter were tested in a fed condition only.
• The dose of each drug was carefully measured to ensure molecular equivalence. The result was 19.9 mg/kg of pivampicillin or 17 mg/kg of ampicillin trihydrate which are both equivalent to 15 mg/kg of ampicillin.
• The concentrations of ampicillin in the plasma of the horses were tracked and recorded for 24-hours following the administration of the drugs.

Results

• The experiment calculated the mean areas under the plasma concentration-time curve (AUC) which represents the total drug exposure over time. The AUCs for pivampicillin given to starved and fed horses were 23.0 and 19.3 micrograms.h.ml-1 respectively, whilst for ampicillin trihydrate in fed horses, it was reported to be significantly lower at 0.7 microgram.h.ml-1.
• Peak plasma concentrations, the highest concentration that a drug achieves in the plasma after its administration, were also recorded. They were highest for pivampicillin in starved horses at 6.7 microgram/ml, 4.8 microgram/ml for fed horses and extremely low for ampicillin trihydrate in fed horses at 0.1 microgram/ml.
• The results indicated no significant statistical difference between the peak plasma concentration or AUC of pivampicillin when administered to starved as opposed to fed horses.

Conclusion

• The research concludes that pivampicillin as an oral paste at a dosage of 19.9 mg/kg gives satisfactory plasma results in both starved and fed horses. The ampicillin trihydrate on the other hand, produces negligible plasma concentrations.
• Both drugs were found to bind with feedstuffs at the pH found in the horse’s stomach and small intestine, with a lesser extent to ampicillin, resulting in decreased bioavailability compared to pivampicillin.
• The researchers also claimed that binding to feedstuffs does not appear to significantly influence the absorption of aminopenicillins.