Accumulation of Ractopamine Residues in Hair and Ocular Tissues of Animals during and after Treatment

Abstract

The aim of the present study was to assess the accumulation of ractopamine residues in the hair and ocular tissues of guinea pigs during repeated ractopamine administration and after treatment. The experiment was conducted in 38 guinea pigs (30 treated and eight controls). Treated animals were orally administered ractopamine hydrochloride in a dose of 3.5 mg/kg body mass per day using probes for seven consecutive days. Ractopamine concentration was determined in hair during the treatment (Days 1, 3 and 7) with ractopamine hydrochloride and in ocular tissues and hair on defined days after exposure (Days 1, 10, 20 and 30). Residues were present in hair in high concentrations as early as Day 3 (86.15 ± 87.71 ng/g) and Day 7 (85.25 ± 56.97 ng/g). After exposure, residues were found to persist, having depleted from 68.06 ± 30.54 ng/g on Day 1 to 8.01 ± 2.22 ng/g on Day 30, with a significantly higher concentration in hair in contrast to low residue levels in ocular tissues (1.20-0.34 ng/g). The results of the study pointed to high ractopamine accumulation, even in non-pigmented hair, suggesting hair to be used as a matrix in the control of ractopamine abuse in farm animals because of its many advantages over ocular tissues.

Residues of Ractopamine and Identification of its Glucuronide Metabolites in Plasma, Urine, and Tissues of Cattle

“…Ractopamine residues in plasma and urine of cattle (mean ± SE, n = 3) fed 0.67 mg/kg body weight of ractopamine for 28 days not surprising to find high ractopamine residue concentrations in lung tissues because ractopamine is a β-agonist in the same category as salbutamol, which is used for the treatment of human asthma. The three tissues with the greatest concentration of residual ractopamine in this study included the eyes, which was inconsistent with previously reported results (15,16). Smith et al (16) demonstrated that the propensity for binding of ractopamine to melanin is weaker than that of clenbuterol and ractopamine was undetectable in whole-eye homogenates from cattle dosed with 0.9 mg/kg per day for 7 days.…”

“…Smith et al (16) demonstrated that the propensity for binding of ractopamine to melanin is weaker than that of clenbuterol and ractopamine was undetectable in whole-eye homogenates from cattle dosed with 0.9 mg/kg per day for 7 days. Likewise, Pleadin et al (15) also reported low ractopamine residue concentrations in the ocular tissues of guinea pigs (0.34-1.20 ng/g) following administration of 3.5 mg/kg body mass of ractopamine for 7 days. However, in the present study, ractopamine residue levels were comparatively high in eye tissues.…”

Assessment of the withdrawal period for ractopamine hydrochloride in the goat and sheep

“…Overall. It is clear that the risk of exposure to ractopamine residues is greater in goat tissues than in sheep tissues (4,25). The residues in liver and became undetectable after 95 h in goat and 82 h in the sheep, similar to delays reported for clenbuterol, a β 2 -agonist, in goat tissues (8,26).…”

“…Introduction β-Agonists exhibit short-acting effects and long-acting effects and are frequently used to promote growth in livestock, but problems arise when the residues of such veterinary drugs have the potential to influence human health after being consumed in animal products (1)(2)(3)(4)(5). Evaluation of β-agonist as a veterinary drug is a new concept to implement the principle using medicines for veterinarian by motto: logic and responsibility.…”

Effect of ractopamine hydrochloride on growth promotion in guinea pigs (Cavia porcellus)

“…Some investigations have used R on guinea pigs (cavies) and other rodents. In the specific case of the guinea pig, which is a laboratory animal model, metabolites of R were traced and measured in different concentrations and in different tissues, such as skeletal muscle (11)(12)(13)(14). The production of this species for human consumption has historically occurred in countries on the American continent, including Andean countries such as Peru and Ecuador (15,16); currently, it is also found in other parts of the world, such as some regions of Cameroon (17)(18)(19).…”