Absorption, Distribution and Excretion
Absorption, distribution, excretion and metabolism in mammals: Based on bile and urinary excretion, at least 47% of a single low dose (2.5 mg/kg) was absorbed. Widely distributed; the highest residual amounts were found in the adrenal glands, kidneys, pancreas, lymph nodes and reproductive fat. No accumulation was observed. 24-hour excretion: 5% to 9% in urine; 85% to 100% in feces. (Data from tables) Fischer 344 rats (5 rats per sex per group) were administered (14)C-milbemycin A4 (14C-E187) by gavage at 2.5 mg/kg (low dose) and 25 mg/kg (high dose) according to the following protocols: (1) a single low dose; (2) a single low dose followed by a single low dose of carbon-14 over 14 consecutive days; (3) a single high dose; (4) a single low dose was administered for pharmacokinetic monitoring; and (5) a single high dose was administered for pharmacokinetic monitoring. Tissue distribution studies were conducted using nine rats (one group per sex) after single oral administration of low and high doses. Bile duct cannulation studies were performed using four rats (one group per sex) after single oral administration of low and high doses. The mean total recovery rates for the single oral administration of low, high, and repeated doses ranged from 93.7% to 106%, with 81.5% to 100% excreted in feces and 3.28% to 9.29% in urine. The remaining tissue concentrations were less than 0.44% of the total residual radioactivity (TRR). Carbon-14 was rapidly excreted, with the majority being eliminated within 24 hours post-administration. Carbon-14 levels detected in bile and urine indicated that approximately 50% of the carbon-14 was absorbed in the low-dose group and approximately 30% in the high-dose group. Plasma carbon-14 concentrations peaked 2 to 3 hours after oral administration. Most of the carbon-14 in tissues was found in the gastrointestinal tract or liver…

---

Metabolism / Metabolites
It is extensively metabolized in animals (the parent compound was not detected in feces or bile at low doses), with hydroxylation as the primary metabolic pathway and some evidence of glucuronidation. (Data from tables) 53 Fischer 344 rats (5 males and 5 females per group) were administered (14)C-milbemycin A4 ((14)C-E187) by gavage… The main metabolite found in plasma, liver, and kidney samples was 13-hydroxyA4, accounting for 60.2%, 52.4%, and 66.7% of the total radioactive residues, respectively. Metabolites identified in feces included dihydroxyA4 (3 metabolites) and trihydroxyA4 (2 metabolites). The main metabolite in urine was dihydroxyA4 (0.95% to 4.38% of the administered dose).

Non-Human Toxicity Values
Oral LD50 in rats: 456 mg/kg /from table/
Oral LD50 in male rats: 5200 mg/kg /Ultiflora Miticide/
Oral LD50 in female rats: 5300 mg/kg /Ultiflora Miticide/
Dermal LD50 in rats: >5000 mg/kg /from table/
For more complete data on non-human toxicity values of MILBEMECTIN (6 types), please visit the HSDB record page.

(6R,25R)-5-O-Demethyl-28-deoxy-6,28-epoxy-25-methylmilbemycin B is a milbemycin. Milbemycin A3 has been reported in *Streptomyces pyriformis*, *Streptomyces avermitosa*, and *Streptomyces milbemycin*, and relevant data are available for reference.

---

Mechanism of Action
...Milbeknock acts on the nervous system through the inhibitory neurotransmitter GABA (gamma-aminobutyric acid).

C31H44O7

528.7

528.309

51570-36-6

9828343

White to light yellow solid powder

1.2±0.1 g/cm3

725.5±60.0 °C at 760 mmHg

233.2±26.4 °C

0.0±5.3 mmHg at 25°C

1.577

5.85

2

7

38

1040

10

C[C@H]1CC[C@]2(C[C@@H]3C[C@H](O2)C/C=C(/C[C@H](/C=C/C=C/4\CO[C@H]5[C@@]4([C@@H](C=C([C@H]5O)C)C(=O)O3)O)C)\C)O[C@@H]1C

ZLBGSRMUSVULIE-GSMJGMFJSA-N

InChI=1S/C31H44O7/c1-18-7-6-8-23-17-35-28-27(32)21(4)14-26(31(23,28)34)29(33)36-25-15-24(10-9-19(2)13-18)38-30(16-25)12-11-20(3)22(5)37-30/h6-9,14,18,20,22,24-28,32,34H,10-13,15-17H2,1-5H3/b7-6+,19-9+,23-8+/t18-,20-,22+,24+,25-,26-,27+,28+,30-,31+/m0/s1

(1R,4S,5'S,6R,6'R,8R,10E,13R,14E,16E,20R,21R,24S)-21,24-dihydroxy-5',6',11,13,22-pentamethylspiro[3,7,19-trioxatetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene-6,2'-oxane]-2-one

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.

---

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).

View More

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)

---

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).

View More

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

---

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.

---

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