Absorption and distribution patterns of oral phenoxymethyl penicillin (penicillin V) in the horse.

The research article discusses the absorption and distribution patterns of an oral antibiotic, phenoxymethyl penicillin, in horses, with findings suggesting its potential for long-term therapy.

Introduction

• The research primarily investigates the absorption and distribution patterns of Phenoxymethyl penicillin (Penicillin V; Pen V) in horses.
• The testing involves oral administration of two different forms of the drug to five healthy horses.
• The overall aim of the study is to gather data that can indicate if oral Pen V is a viable option for long-term penicillin therapy in horses.

Methodology

• Tests were conducted by giving two formulations of the drug orally to five healthy horses, and then measuring the serum levels of phenoxymethyl penicillin.
• The study uses a two-compartment model to describe the mean serum concentration profile, with a first order rate of absorption. This model analyzes the absorption stage when the drug enters the system, and the elimination stage when the drug is removed from the system.
• The study then calculated the half-lives of three stages, namely the absorption, distribution, and elimination phases. Half-life is the time the drug takes to reduce to half of its initial concentration.

Results

• The results show the half-lives of the absorption, distribution, and elimination stages are respectively 0.199 +/- 0.035, 0.362 +/- 0.060, and 3.650 +/- 0.575 hours.
• The researchers further checked the distribution of the drug to body fluid compartments other than serum, such as synovial fluid, peritoneal fluid, and urine.
• The observations revealed the following mean peak levels: 2.38 +/- 0.18 in serum, 0.35 +/- 0.02 in synovial fluid, 0.25 +/- 0.06 in peritoneal fluid, and 472 +/- 80 micrograms/ml in urine.
• The time to reach peak concentration varied from 30 to 360 minutes post oral administration of the drug.

Conclusion

• The steady-state pharmacokinetic measurements concluded that minimum serum Pen V concentrations of 0.1 micrograms/ml could be maintained by oral administration of the drug (110,000 I.U./kg) at 8-hour intervals.
• The recorded data from this study strongly suggests that oral Pen V may be a feasible approach for long-term penicillin therapy in equine patients.