Variability in plasma concentrations of methylprednisolone 6 days after intrasynovial injection of methylprednisolone acetate in racing horses: A field study.

BACKGROUND: Methylprednisolone (MP) acetate is a commonly used corticosteroid for suppression of inflammation in synovial structures in horses. Its use is often regulated in equine sports by plasma MP concentrations. OBJECTIVES: To describe variability in MP plasma concentrations after MP acetate injection in different synovial structures and with co-administration with hyaluronic acid (HA). STUDY DESIGN: Field study in actively racing horses in three disciplines (Thoroughbred, Standardbred and Quarter Horse). METHODS: Seventy-six horses (15 Thoroughbreds, 20 Standardbreds and 41 Quarter Horses) were included in the study. Injection of any synovial structure with a total body dose of 100 mg MP acetate was permitted, data were grouped according to the synovial structure injected and co-administration with HA. Plasma was collected before injection and at 6 days post-injection. Per cent censored data (below the limit of quantification) for each synovial structure were determined, and summary statistics generated by Robust Regression on Order. Differences between synovial structures and co-administration with HA were identified by ANOVA with Tukey's post hoc testing. RESULTS: The MP plasma concentration at 6 days for injection for the entire group (mean ± standard deviation [s.d.], pg/mL) was 96 ± 104. Metacarpophalangeal (MCP) plasma concentrations contained 86% censored data and could not be included in the statistical analysis. The carpal joints (CJO) group had a lower plasma MP concentration (P<0.05) than the distal tarsal joints (DTJ) or medial femorotibial (MFT), the no HA (NHA) group had a lower plasma MP concentration (P<0.05) than HA. MAIN LIMITATIONS: The synovial structures injected varied by racing discipline, so this study was unable to identify any differences between disciplines. CONCLUSIONS: Practitioners should be aware that injection of DTJ, CS and MFT joints, and combining MP acetate with HA may prolong its clearance, and withdrawal times for competition in regulated equine sports.

Application of a convenient extraction procedure to analyze gamma-hydroxybutyric acid in fatalities involving gamma-hydroxybutyric acid, gamma-butyrolactone, and 1,4-butanediol.

The most common chemicals that can be ingested and lead to greater than endogenous levels of gamma-hydroxybutyric acid (GHB) in decedents are salts of GHB, gamma-butyrolactone (GBL), and 1,4-butanediol (BD). Results for three deaths involving the ingestion of one or another of these three chemicals, which led to findings of GHB in the decedents, are presented. An extraction procedure that facilitates the quantitation of GHB was developed. If present in the same specimen, both GHB and GBL can be quantitated. To determine the GBL concentration, the specimen is first analyzed for existing GHB, the GBL is then converted to GHB, and the analysis is repeated. The difference between the results in molarity units can yield the GBL concentration. A separate procedure was utilized for estimating concentrations of BD. Specimens analyzed included urine, blood, ocular fluid, brain, and solutions consumed by the decedents prior to death. The procedures were found to be convenient in as much as they are relatively rapid, precise, and economical.

Trends in HIV seroprevalence, AIDS and prevention policy among intravenous drug users and men who have sex with men, before and after 1990 in Austria.

This study reports for the first time on secular trends in human immunodeficiency virus (HIV) infection and AIDS, and possible associations with prevention policy in Austria. We analysed HIV seroprevalence and AIDS cases among intravenous drug users (IDU) and men who have sex with men (MSM). In this study we found a diminished rate of increase in new cases of AIDS and a decline in HIV seroprevalence among IDU but not among MSM. Among clients visiting HIV counselling and testing centres in Austria between 1987 and 1990, seroprevalence among IDU was estimated at 27.9% as compared to 19.6% between 1990 and 1992 (odds ratio (OR): 0.62; 0.45-0.85). Among MSM corresponding prevalence for these two periods was 12.1% and 10.9%, respectively, which was not a significant decline. In the period 1990 to 1994, the increase in AIDS cases per half-year levelled off for IDU (incidence rate ratio (IRR) :1.00; 0.99-1.01) but to a lesser extent among MSM (IRR: 1.01; 1.01-1.02). The most effective prevention policy intervention was considered to be the national Methadone Maintenance Program (MMTP), started in 1987, and the provision of sterile injection equipment. We observed that in the recent period there was a decline in the frequency of attendance among young (less than 28 years of age) MSM at counselling centres (OR: 1.27; 95 % CI: 1.08-1.49), accompanied by the observation that the rate of seroprevalence among this group did not decline. This is in contrast to young IDU where attendance did not decline but seroprevalence did. Although inference is limited from cross sectional studies, we argue for a reoriented and effectively monitored HIV prevention policy focused on young MSM.

Determination of bromide ion concentration in greyhound urine by ion chromatography.

An ion chromatographic method was used to determine Br ion in the urine of Greyhounds. Phenol was added to the urine, before filtration through a 30,000-molecular weight cutoff filter and to the eluant (pH 11, NaOH-Na2CO3), as a preservative. Urine from 103 racing Greyhounds resulted in a mean +/- SD of 3.60 +/- 2.72 mg of Br/L of urine. Urine samples obtained from a Greyhound, to which 2 g of KBr was administered, yielded a diurnal elimination pattern with a half-life of 7.6 days.

Plasma and serum concentrations of phenylbutazone and oxyphenbutazone in racing Thoroughbreds 24 hours after treatment with various dosage regimens.

The plasma and serum concentrations of phenylbutazone (PBZ) and oxyphenbutazone were measured in 158 Thoroughbred horses after various doses of PBZ wer given. All horses were competing or training at racetracks in various parts of the country. All horses used in the study had not been given PBZ 24 hours before they were placed on a specific dosage schedule. Samples were collected 24 hours after the last PBZ administration. Four grams of PBZ were given daily by stomach tube, paste, or tablet for 3 days. On day 4, 24 hours before sample collection, an IV dose of 2 g of PBZ was given, regardless of the dose and method of administration. The 24-hour PBZ plasma concentrations were 3.51, 6.13, and 6.40 micrograms/ml, respectively. After 2 g of PBZ was administered IV daily for 4 days, the plasma PBZ concentration was 4.16 g/ml; after a single 2-g IV administration, the serum concentration was 0.87 g/ml. Concentrations of oxyphenbutazone were 3.35 (stomach tube), 4.29 (paste), 3.60 (tablet), 3.65 (4-day IV), and 1.11 g/ml (single IV). A significant relationship was not found between the serum and the urinary concentrations at this 24-hour measurement. Split samples sent to various laboratories confirmed the stability of high-performance liquid chromatography as a method of analysis.

Procaine in the urine of racing Greyhounds: possible sources.

Greyhounds (n = 25) were given procaine in the form of procaine HCl or procaine penicillin G or were fed meat prepared from a heifer given procaine penicillin G on 3 consecutive days before slaughter. Dogs given procaine HCl or procaine penicillin G were given daily doses equivalent to 9 mg of procaine/kg. Urine samples were collected from the dogs twice daily before dosing, during the dosing period, and for 4 days after final dose administration. All dogs excreted detectable concentrations of procaine in the urine, regardless of the dose form or route of administration. Blood plasma samples were prepared from 10 Greyhounds to determine procaine esterase activity. Hydrolysis of procaine by plasma esterases did not occur. Low plasma procaine esterase activity, coupled with rapid oral absorption of procaine, resulted in high urinary concentrations of the parent drug in dogs given procaine HCl or procaine penicillin G (9 mg/kg). Even in the dogs given relatively small doses (0.85 mg/kg) of procaine in the form of meat residues, urinary procaine concentrations were found. The results of these studies indicate that procaine is rapidly absorbed following oral administration and that meat from livestock given procaine penicillin before slaughter may serve as a source of urinary procaine in Greyhounds consuming the meat.