Actividad antibacteriana in vitro y biodisponibilidad en vacas de varios preparados de benzilpenicilina g, sola o combinada con sulfato de dihidroestreptomicina

Abstract

PRODUCERS OF BENZYLPENICILLIN-G (BP-G) SEEK COMPETITIVENESS NOT ONLY THROUGH THE ACTUAL COST/IU OF ACTIVITY, BUT ALSO BY MODIFYING TRADITIONAL POWDER PREPARATIONS, I.E., AS PRE-SUSPENDED-STABLE SUSPENSIONS. CONSIDERING THE LACK OF STABILITY OF B-LACTAM ANTIBACTERIALS WHEN SUSPENDED, AND THE DIFFERENT TYPES AND PROPORTIONS OF BP-G SALTS PRESENT IN A GIVEN PREPARATION, NOTICEABLE ALTERATIONS IN THE IN VITRO ACTIVITY AND BIOAVAILABILITY COULD OCCUR. TO TEST THESE HYPOTHESES, 3 POWDER PREPARATIONS OF BP-G, AND 3 IDENTICALLY FORMULATED PREPARATIONS OF PRE-SUSPENDED BP-G, AS WELL AS A PROCAINE-BP-G POWDER PREPARATION WERE EVALUATED TO DETERMINE THEIR MINIMAL INHIBITORY CONCENTRATIONS IN VARIOUS BACTERIA. BIOAVAILABILITY WAS ALSO ASSESSED USING AN AGAR PLATE DIFFUSION TEST TO ESTIMATE THE ANTIBACTERIAL-CONCENTRATION ACTIVITY (ACA) OF THE PREPARATIONS, MAXIMUM PLASMA ACA (CPMAX), AND TIME TO CPMAX (TMAX), AFTER ONE BOLUS IM DOSE. RESULTS SHOW THAT POWDER PREPARATIONS OF BP-G HAD GREATER IN VITRO POTENCY THAN PRE-SUSPENDED PREPARATIONS OF THIS ANTIBACTERIAL. POTENCY OF POWDER PREPARATIONS WERE AT LEAST TWO FOLD GREATER THAN THE PRE-SUSPENDED ONES. CPMAX VALUES WERE GREATER WHEN PROCAINE BP-G WAS USED, AND MINIMUM WITH THE PREPARATIONS CONTAINING BENZATHINE BP-G. PREPARATIONS CONTAINING DIHYDROSTREPTOMYCIN SULPHATE SHOWED GREATER ACA THAN DIHYDROSTREPTOMYCIN-FREE PREPARATIONS; HOWEVER, DIFFERENCES WERE NOT STATISTICALLY SIGNIFICANT (P>O.05). THIS INFORMATION MAY BE OF VALUE TO CLINITIANS IN PARTICULAR WHEN EFFICACY OF BP-G AGAINST A GIVEN DISEASE IS BORDERLINE. THESE RESULTS QUESTION THE CONCEPT OF ADDING DIHYDROSTREPTOMYCIN TO BP-G PREPARATIONS, AND PONDER PROCAÍNE BP-G AS THE PENICILLIN OF CHOICE FOR CATTLE.