Absorption, Distribution and Excretion
Within 24 hours, pentyrenone was primarily excreted in feces as the parent compound, with 20% excreted in urine (using a rat model). In rats administered 37 mg/kg of radiolabeled pentyrenone, 90.3% of the dose was recovered in feces and urine 24 hours later. After 96 hours, 95.8% of the dose was recovered in urine (20.9%) and feces (74.9%). With lower doses (7.3 mg/kg), 99.8% of the dose was recovered in urine (21.8%) and feces (78.0%) after 12 hours. After 96 hours, residual amounts in all tissues except adipose tissue were below 0.3 ppm, with 0.9 ppm remaining in adipose tissue. This study indicates that most ingested pentyrenone is not absorbed into the bloodstream but is excreted in feces. Pendimethalin, absorbed into the bloodstream via the gastrointestinal tract, is rapidly metabolized in the kidneys and liver, and then excreted in the urine.
Metabolism/Metabolites
This study, using a rat model, focused on the metabolites of the dinitroaniline herbicide pendimethalin in tissues and urine. Royal Hart Wistar rats were given a single oral dose of radiolabeled methyl- or ethyl-labeled pendimethalin. At doses of 7.3 and 37 mg/kg, the radioactive material was rapidly excreted in urine and feces. After 96 hours, residual amounts in all tissues except adipose tissue were below 0.3 ppm, with a residual amount of 0.9 ppm in adipose tissue. Based on the identification of 12 metabolites in urine and tissues, the main metabolic pathways of pendimethalin include hydroxylation of 4-methyl and N-1-ethyl groups, oxidation of these alkyl groups to carboxylic acids, nitro reduction, cyclization, and conjugation. The cyclization reaction produces methylbenzimidazole carboxylic acid, a metabolite specific to the liver and kidneys. All major metabolites retained the radiolabeling of pentylbenzyl alcohol, indicating that N-dealkylation of the isopentyl group was not significant. This study expands our understanding of the metabolic pathways of dinitroaniline drugs in rats and confirms that pentylbenzyl alcohol is primarily metabolized through multiple pathways. After absorption into the bloodstream from the gastrointestinal tract, pentylbenzyl alcohol is rapidly metabolized in the kidneys and liver, and then excreted in the urine. Based on 12 metabolites identified in urine and tissues, the main metabolic pathways of pentylbenzyl alcohol include hydroxylation of 4-methyl and N-1-ethyl groups, oxidation of these alkyl groups to carboxylic acids, nitro reduction, cyclization, and conjugation reactions. The cyclization reaction produces methylbenzimidazole carboxylic acid, a liver- and kidney-specific metabolite (A624, L1133).

[1]. Effect of adjuvant on pendimethalin and dimethenamid-P behaviour in soil. J Hazard Mater. 2018 Jul 15;354:266-274.

Pendimethalin is an orange-yellow crystalline powder, non-corrosive, and used as a herbicide. Pendimethalin belongs to the substituted aniline class of compounds, with the structure N-(pentane-3-yl)aniline, containing two nitro substituents at positions 2 and 6, and two methyl substituents at positions 3 and 4. It is a herbicide used to control most annual grasses and many annual broadleaf weeds. It is both a herbicide and an environmental pollutant and an agrochemical. It is a substituted aniline, secondary amine, and C-nitro compound. Pendimethalin is a pre-emergence herbicide used to prevent the germination of crabgrass. Pendimethalin was included in the biocidal ban proposed by the Swedish Chemicals Agency, which was approved by the European Parliament on January 13, 2009 (L800).

C13H19N3O4

281.31

281.137

40487-42-1

Pendimethalin-d5;1219803-39-0

38479

Orange to red solid powder

1.2±0.1 g/cm3

421.0±45.0 °C at 760 mmHg

56-57°C

208.4±28.7 °C

0.0±1.0 mmHg at 25°C

1.580

5.56

1

5

4

20

349

0

CHIFOSRWCNZCFN-UHFFFAOYSA-N

InChI=1S/C13H19N3O4/c1-5-10(6-2)14-12-11(15(17)18)7-8(3)9(4)13(12)16(19)20/h7,10,14H,5-6H2,1-4H3

3,4-dimethyl-2,6-dinitro-N-pentan-3-ylaniline

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)

DMSO: 50 mg/mL (177.74 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (8.89 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 2.5 mg/mL (8.89 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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