pig β1AR ~25 nM (Kd) pig β2AR ~25 nM (Kd)

Pig muscle protein accretion is reliably increased by ractopamine[3].

Absorption, Distribution and Excretion
This study investigated the detection, confirmation, and metabolism of ractopamine, a β-adrenergic agonist administered to horses in Paylean form. …Based on quantitative ion analysis of ractopamine standards extracted from urine, standard curves showed a linear response for ractopamine concentrations between 10 and 100 ng/mL, with a correlation coefficient r > 0.99; while standards with concentrations ranging from 10 to 1000 ng/mL exhibited a second-order regression curve, r > 0.99. …Twenty-four hours after oral administration of 300 mg ractopamine, the concentration of parent ractopamine in urine was determined to be 360 ng/mL by GC-MS. Urinary metabolites were identified using electrospray ionization tandem quadrupole mass spectrometry, revealing the presence of glucuronide, methyl, and mixed methyl-glucuronide conjugates. In a Good Laboratory Practice (GLP) bioavailability study, five male and five female rats were administered a single oral dose of [14C]-ractopamine via gavage at doses of 0.5, 2.0, or 20 mg/kg body weight. Plasma and whole blood samples were collected within 24 hours of administration for quantitative analysis of the radiolabeled content. Comparison of the area under the concentration-time curve (AUC) of plasma and whole blood showed that the bioavailability of [14C]-ractopamine in both male and female rats was dose-dependent at doses up to 2.0 mg/kg body weight. Increasing the dose to 20 mg/kg body weight resulted in a further increase in AUC for males, with a more significant increase in females. Since intravenous administration of (14)C-ractopamine was not performed in this study, the AUC values of oral and intravenous administration could not be compared, and therefore the absolute bioavailability of (14)C-ractopamine in rats could not be determined. To determine the total residual amount of (14)C-ractopamine hydrochloride in the ocular tissues of cattle and turkeys after oral administration, we conducted the following experiments. Twelve cattle were administered 0.9 mg/kg/d of (14)C-ractopamine hydrochloride via rumen gavage for seven consecutive days. Four cattle were slaughtered after withdrawal periods of 48, 96, and 144 hours, respectively. No radioactive residues were detected in the whole-eye homogenates of the cattle. Eight male and eight female turkeys in each treatment group were fed 7.5, 22.5, or 30 ppm of (14)C-ractopamine hydrochloride (dose of 0.33, 1.02, and 1.36 mg/kg/d, respectively; corresponding to treatment groups 1, 2, and 3) for seven consecutive days and were slaughtered after a 0-day withdrawal period. The eyeballs were dissected into three parts: retina/choroid/sclera (RCS), cornea/iris (CI), and aqueous humor (AH). No residues were detected in the RCS, CI, and AH of turkeys in treatment group 1. In treatment groups 2 and 3, the residue level in AH was below 0.02 ppm. The mean residue level in RCS ranged from 0.15 to 0.26 ppm, while the mean residue level in CI ranged from <0.09 to 0.17 ppm (corresponding to treatment groups 2 and 3, respectively). Ractopamine hydrochloride is a β-adrenergic lean meat enhancer recently approved for use in pigs. The consumption of ractopamine in tissues and the clearance of ractopamine and its metabolites in urine are important for detecting off-label use. This study aimed to determine the ractopamine residues in the liver and kidneys of cattle (n = 6), sheep (n = 6), and ducks (n = 9) after continuous feeding with ractopamine for 7 days (sheep, ducks) or 8 days (cattle), and to determine the consumption of ractopamine in the urine of cattle and sheep. Two cattle, two sheep, and three ducks were slaughtered, with withdrawal periods of 0, 3, and 7 days, respectively. Urine samples were collected daily from the cattle and sheep. The concentration of ractopamine in pig tissues was determined using a regulatory method for ractopamine (FDA approved). The residual amount of ractopamine in urine samples was determined before and after hydrolysis of the conjugate. High-performance liquid chromatography (HPLC) combined with fluorescence detection was used for liquid-phase extraction and/or solid-phase extraction of the hydrolyzed samples. No residues were detected in the duck tissues. The residual amount of ractopamine in sheep liver was 24.0 ppb and 2.6 ppb after 0 and 3 days of withdrawal, respectively. After 7 days of withdrawal, the residual amount of ractopamine in sheep liver was below the limit of quantitation (2.5 ppb). The residual amount of ractopamine in sheep kidney was 65.1 ppb and undetectable after 0, 3, and 7 days of withdrawal, respectively. The drug residue levels in bovine liver were 9.3 ppb, 2.5 ppb, and undetectable on days 0, 3, and 7 after drug withdrawal, respectively; the drug residue levels in kidneys were 97.5 ppb, 3.4 ppb, and undetectable on the same withdrawal days. The concentration of maternal ractopamine in sheep urine was 9.8 ± 3.3 ppb on day 0 after drug withdrawal, and below the limit of quantitation (5 ppb) after a 2-day withdrawal period. After hydrolysis of the conjugate, the ractopamine concentration was 5,272 ± 1,361 ppb on day 0 after drug withdrawal and 178 ± 78 ppb on day 7 after drug withdrawal. The concentration of ractopamine in bovine urine ranged from 164 ± 61.7 ng/mL (day 0 after drug withdrawal) to below the limit of quantitation (50 ppb) (day 4 after drug withdrawal). After hydrolysis of the conjugate in bovine urine, ractopamine concentrations ranged from 4,129 ± 2,351 ppb (day 0 after drug withdrawal) to below the limit of quantitation (day 6 after drug withdrawal). These data indicate that, after conjugate hydrolysis, ractopamine can be detected in sheep urine up to 7 days after the last administration, and in bovine urine up to 5 days after drug withdrawal. For more complete data on the absorption, distribution, and excretion of ractopamine (16 items in total), please visit the HSDB record page. Metabolites/Metabolites Only a very small fraction of the recovered radioactive material in urine is parent ractopamine. In pigs, approximately 4–16% of the parent compound is excreted in urine after a single oral administration of ractopamine. With repeated administration, the unmetabolized drug content in urine collected on day 4 of a 4-day dosing regimen increases to 36–85% of total radioactivity. In rats intraperitoneally injected with 9 mg/kg body weight of (14)C-ractopamine, the parent drug accounted for 22.6% of the total radioactivity in urine; while after oral administration of 9.9 mg/kg body weight of ractopamine, only 1.9% of the radioactivity was associated with unmetabolized ractopamine. The higher proportion of parent drug in urine after parenteral administration compared to oral administration indicates that the liver and intestines play important roles in the biotransformation of ractopamine after oral administration. Therefore, although ractopamine is well absorbed by the gastrointestinal tract, its systemic bioavailability is reduced due to significant first-pass metabolism. At least seven distinct crude metabolite components were isolated by chromatography from the bile of rats orally administered (14)C-ractopamine. Four were isolated and identified from the crude metabolite components representing 76% of the bile radioactivity, with the sulfate/glucuronic acid diconjugate of ractopamine being the major metabolite (accounting for 46% of the total bile radioactivity). Another 6% of the radioactivity was identified as ractopamine monosulfate conjugates, and 25% as ractopamine monoglucuronide. The sulfation site was determined to be on C-10' phenol (an aromatic ring linked to methanol). This sulfate binding was not stereoselective. The main glucuronidation site was C-10 phenol (a phenolic hydroxyl group linked to a nitrogen substituent). Six hours after drug withdrawal (rats, dogs) or 12 hours after drug withdrawal (pigs, cattle), unmetabolized ractopamine accounted for 40%, 14%, 52%, and 13-16% of the total extractable and identifiable residues in the livers of rats, dogs, pigs, and cattle, respectively, and 21%, 29%, 28-30%, and 14% in the kidneys, respectively. Twenty-four and seven-two hours after drug withdrawal, parent ractopamine accounted for 14.1% and 3.6% of the total residues in the livers of pigs, respectively, and 27.5% and 3% in the kidneys, respectively. The remaining residues were ractopamine conjugates. The chromatograms of the 14C-labeled residue extracts from the livers of rats, dogs, pigs, and cattle were qualitatively similar. The proportion of metabolite residues in experimental animals is generally high. Studies in rats and dogs showed that the urine of animals given 14C-labeled ractopamine contained the same four ractopamine glucuronide metabolites as those in pigs. This led to the conclusion that the metabolites exposed to dogs and rats in toxicology studies were the same as those found in edible tissues of pigs and cattle. A fourth metabolite, glucuronide diconjugate, was identified in studies of rats, dogs, pigs, and cattle fed 14C-labeled ractopamine. The conjugation reaction between the aromatic ring attached to the alcohol hydroxyl group and the phenolic hydroxyl group attached to the nitrogen substituent was not stereoselective. For more complete metabolite/metabolite data on ractopamine (8 metabolites in total), please visit the HSDB record page.

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Biological Half-Life
Elimination half-life = 6-7 hours; [HSDB]
The elimination half-life is approximately 6-7 hours.
A study of six healthy male volunteers showed that after a single oral dose of 40 mg ractopamine hydrochloride, its pharmacokinetics and biotransformation characteristics were similar in humans and animals. …The plasma half-life is approximately 4 hours.

Interactions
This study conducted an 8-week investigation to explore the effects of conjugated linoleic acid (CLA), animal fats, and ractopamine, and their interactions, on the growth, fatty acid composition, and carcass quality of genetically lean pigs. 228 sows (initial body weight 59.1 kg) were selected and treated with CLA, ractopamine, and fats using a 2×2×3 factorial design. CLA treatment included the addition of 1% CLA oil (CLA-60) or 1% soybean oil. Ractopamine concentrations were 0 or 10 ppm. Fat treatments included no fat addition, the addition of 5% selected white fat (CWG), or 5% tallow (BT). Both CLA and fat treatments began when sows reached 59.1 kg, 4 weeks earlier than the ractopamine treatment. Ractopamine treatment began when sows reached 85.7 kg and continued for the final 4 weeks until carcass data were collected. Lipids were extracted from the abdomen, inner and outer backfat layers, and eye muscles of six pigs in each treatment group at weeks 4 and 8, and their fatty acid composition was analyzed. Feeding with conjugated linoleic acid (CLA) significantly improved the feed conversion ratio (G:F) in the last four weeks (P < 0.02). Pigs fed with added fat (in CWG or BT form) showed a significant decrease in average daily feed intake (ADFI) (P < 0.05) and a significant increase in feed conversion ratio (P < 0.01). Dietary supplementation with ractopamine significantly improved average daily gain (ADG), feed conversion ratio, and final body weight (P < 0.01). Pigs fed with CLA or ractopamine showed a significant increase in predicted carcass lean meat percentage (P < 0.05). Feeding with 5% fat or ractopamine both significantly increased carcass body weight (P < 0.05). Dietary fat supplementation significantly increased (P < 0.05) backfat thickness at the 10th rib, but had no effect on predicted lean meat percentage. Sows fed conjugated linoleic acid (CLA) had firmer abdomens, both subjectively and objectively (P < 0.01). Dietary CLA supplementation significantly increased (P < 0.01) the concentration of saturated fatty acids in abdominal fat, backfat, and eye muscle (LM), and significantly decreased (P < 0.01) the concentration of unsaturated fatty acids. Ractopamine significantly decreased (P < 0.01) intramuscular fat content in the eye muscle, but its effect on tissue fatty acid composition was relatively smaller compared to CLA. These results indicate that CLA, added fat, and ractopamine primarily promote growth and carcass quality in pigs in an additive manner. Furthermore, these results also suggest that CLA can increase the saturated fat content in various carcass parts.

[1]. Stress susceptibility in pigs supplemented with ractopamine. J Anim Sci. 2013;91(9):4180-4187.

[2]. Ractopamine increases total and myofibrillar protein synthesis in cultured rat myotubes. J Nutr. 1990;120(12):1677-1683.

[3]. S. E. Mills, Biological basis of the ractopamine response, Journal of Animal Science, Volume 80, Issue E-suppl_2, 2002, Pages E28–E32.

4-(1-hydroxy-2-{[4-(4-hydroxyphenyl)but-2-yl]amino}ethyl)phenol is a secondary amino compound, a derivative of 4-(2-amino-1-hydroxyethyl)phenol, in which a hydrogen atom bonded to a nitrogen atom is replaced by a 4-(p-hydroxyphenyl)but-2-yl group. It is a polyphenol, secondary amino compound, benzyl alcohol, and secondary alcohol.
See also: Ractopamine hydrochloride (in salt form).

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Mechanism of Action
The RR isomer (budopamine) is the most active stereoisomer of the β-adrenergic receptor. Budopamine has been shown to be a non-selective ligand for both β1- and β2-adrenergic receptors, but its signal transduction efficiency through the β2-adrenergic receptor is higher than that through the β1-adrenergic receptor. Therefore, the RR isomer of ractopamine is considered a complete agonist of the β2-adrenergic receptor and a partial agonist of the β-adrenergic receptor. These results are consistent with the pharmacological characteristics of racemic ractopamine in isolated heart (atria) and smooth muscle (costal uterine muscle, vas deferens, trachea). Compared with the complete β1 and β2 adrenergic receptor agonist isoproterenol, ractopamine showed a maximum response at β2 adrenergic receptors and a submaximal response at β1 adrenergic receptors.

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Therapeutic Use
MeSH Title: Adrenergic β-Agonists
Veterinary Drugs: Animal Growth Promoters
Veterinary Drugs: Ractopamine, a β-agonist approved for use in finishing pigs and cattle to improve carcass quality and production performance, was investigated for its effects on two important foodborne pathogens—Escherichia coli O157:H7 and Salmonella. Oral administration of ractopamine to sheep before and after inoculation with E. coli O157:H7 increased (P < 0.01) fecal bacterial shedding and tended to increase (P = 0.08) the number of challenged strains in the cecum. Adding ractopamine to pig feed followed by experimental infection with Salmonella typhimurium resulted in reduced fecal bacterial shedding (P < 0.05) and a decrease in the number of positive challenged strains in liver samples (P = 0.05). Pure cultures of E. coli O157:H7 (the strain used in this sheep study), E. coli O157:H19 (isolated from pigs with post-weaning diarrhea), Salmonella typhimurium (the strain used in this pig study), and Salmonella choleraesuis were co-cultured with different concentrations of ractopamine to determine whether ractopamine had a direct effect on bacterial growth. No differences in growth rates were observed between the two Escherichia coli strains and Salmonella typhimurium when incubated with increasing concentrations of ractopamine. Adding 2.0 μg/ml ractopamine increased the growth rate of Salmonella choleraesuis compared to other concentrations tested. Overall, these results suggest that ractopamine may affect the gut microbiota and fecal excretion of Escherichia coli O157:H7 and Salmonella. Given that ractopamine is currently approved for immediate pre-slaughter feeding to fattening cattle and pigs, its potential role in reducing foodborne pathogens has exciting food safety implications.
Drugs (Veterinary Drugs): An 8-week study investigated the effects of conjugated linoleic acid (CLA), animal fat, and ractopamine and their interactions on the growth, fatty acid composition, and carcass quality of genetically lean pigs. Twenty-eight gilts with an initial body weight of 59.1 kg were randomly assigned to a 2×2×3 factorial design to receive conjugated linoleic acid (CLA), ractopamine, or fat treatments. The CLA treatment consisted of either 1% CLA oil (CLA-60) or 1% soybean oil. Ractopamine was added at 0 ppm and 10 ppm, respectively. The fat treatments consisted of no fat, 5% selected white fat (CWG), or 5% tallow (BT). The CLA and fat treatments began when the gilts reached 59.1 kg, four weeks earlier than the ractopamine treatment. Ractopamine treatment began when the gilts reached 85.7 kg and continued for four weeks until carcass data were collected. At weeks 4 and 8, lipids were extracted from the abdomen, inner and outer backfat layers, and eye muscles of six gilts from each treatment group, and their fatty acid composition was analyzed. Feeding with conjugated linoleic acid (CLA) significantly increased the feed conversion ratio (G:F) in the last 4 weeks (P < 0.02). Pigs fed with added fat (in CWG or BT form) showed a significantly decreased average daily feed intake (ADFI) (P < 0.05) and a significantly increased feed conversion ratio (P < 0.01). Dietary supplementation with ractopamine significantly increased (P < 0.01) average daily gain (ADG), feed conversion ratio, and final body weight. Pigs fed with CLA or ractopamine showed a significantly increased predicted carcass lean percentage (P < 0.05). Feeding with 5% fat or ractopamine both significantly increased (P < 0.05) carcass weight. Dietary supplementation with fat significantly increased (P < 0.05) backfat thickness at the 10th rib, but had no significant effect on predicted lean percentage. Sows fed conjugated linoleic acid (CLA) had firmer abdomens, both subjectively and objectively (P < 0.01). Dietary CLA supplementation increased (P < 0.01) the concentration of saturated fatty acids in abdominal fat, backfat, and eye muscle (LM), and decreased (P < 0.01) the concentration of unsaturated fatty acids. Ractopamine decreased (P < 0.01) intramuscular fat content in the eye muscle, but its effect on tissue fatty acid composition was relatively smaller compared to CLA. These results indicate that CLA, added fat, and ractopamine primarily promote growth and carcass quality in pigs in an additive manner. Furthermore, these results suggest that CLA can result in a higher saturated fat content in the carcass.
For more complete data on the therapeutic uses of ractopamine (8 in total), please visit the HSDB record page.

C18H23NO3

301.38

301.167

97825-25-7

56052

Typically exists as solid at room temperature

1.2±0.1 g/cm3

520.5±50.0 °C at 760 mmHg

165-167ºC

165.3±20.7 °C

0.0±1.4 mmHg at 25°C

1.609

1.65

4

4

7

22

297

0

OC1C=CC(CCC(C)NCC(C2C=CC(O)=CC=2)O)=CC=1

YJQZYXCXBBCEAQ-UHFFFAOYSA-N

InChI=1S/C18H23NO3/c1-13(2-3-14-4-8-16(20)9-5-14)19-12-18(22)15-6-10-17(21)11-7-15/h4-11,13,18-22H,2-3,12H2,1H3

4-[3-[[2-hydroxy-2-(4-hydroxyphenyl)ethyl]amino]butyl]phenol

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)