Immunoassay detection of drugs in racing horses. IX. Detection of detomidine in equine blood and urine by radioimmunoassay.

Detomidine is a potent non-narcotic sedative agent which is currently in the process of being approved for veterinary clinical use in the United States. Since no effective screening method in horses is available for detomidine, we have developed an 125I radioimmunoassay for detomidine in equine blood and urine as part of a panel of tests for illegal drugs in performance horses. Our 125I radioimmunoassay has an I-50 for detomidine of approximately 2 ng/ml.

Immunoassay detection of drugs in racing horses. VII. Detection of acepromazine in equine urine and blood by ELISA and PCFIA.

We have developed and evaluated a one step enzyme-linked immunosorbent assay (ELISA) test and a particle concentration fluorescence immunoassay (PCFIA) test for acepromazine as part of a panel of pre- and post-race tests for illegal medications in racing horses. These tests are rapid, sensitive and economical and development of the tests occurred in less than seven months. The ELISA test detects acepromazine with an I-50 of about 150 pg/ml.

Pharmacology of procaine in the horse: evidence against the existence of a "procaine - penicillin" complex.

It has recently been suggested that procaine penicillin existed in solution in vitro and in vivo as a "procaine - penicillin" complex rather than as dissociated ions. In vivo, this complexed procaine was considered unavailable for hydrolysis by plasma esterases or for interaction with pharmacologic receptors for procaine. When procaine penicillin was intramuscularly given to horses, about 90% of the procaine in blood drawn from these horses was split at the same rate as authentic procaine or procaine penicillin added to equine blood in vitro.

Pharmacology of procaine in the horse: procaine esterase properties of equine plasma and synovial fluid.

Procaine added to whole equine blood or diluted plasma was hydrolyzed with half times of approximately 9 and 12 minutes, respectively, at 37 C. This hydrolytic activity was sensitive to heating and physostigmine, but did not affect procainamide. At pharmacologic concentrations of procaine, the rate of the hydrolytic reaction depended directly on the concentrations of plasma or procaine in the system and was less in whole blood than in plasma.