Absorption, Distribution and Excretion
The patterns of absorption and translocation of 14(C) clopyralid commercially formulated as the acid, monoethanolamine salt, potassium salt, 2-ethylhexyl ester and 1-decyl ester were compared in Cirsium arvense and Polygonum convolvulus grown under three environmental regimes. Plants were grown under a 35% or 65% RH regime in silica sand maintained at 33% w/w moisture or under a water stress regime at 65% RH. Approximately 26, 39, 86, 93 and 100% of the applied 14(C)-activity from the 2-ethylhexyl ester, acid, monoethanolamine salt, 1-decyl ester and potassium salt, respectively, were recovered 72 h after application to glass cover slips placed in the growth room. However, loss of applied 14(C)-activity after application of the five formulations to both plant species was significant only for the 2-ethylhexyl ester. Regardless of environmental regime, the acid was the most readily absorbed formulation. In contrast to the acid, the salts and esters were less readily absorbed. When the data were expressed as a percentage of absorbed radioactivity, there was no significant difference in translocation when the acid, monoethanolamine salt and potassium salt were compared. However, significantly smaller quantities of the absorbed 2-ethylhexyl and 1-decyl ester were exported from the treated leaf. These results indicate that once absorbed, the esters do not readily partition out of the cuticle, whereas the acid and two salts move into the symplast for subsequent translocation. When the results of the three environmental regimes were compared, the absorption of the monoethanolamine and potassium salts were greatly reduced under low humidity or water stress, whereas the acid and esters were not affected.
Groups of 5 Crl:CD (F-344) BR rats/sex were dosed with single iv treatments of (14)C-labeled clopyralid, either 5 mg/kg in saline, by single gavage doses of 5 or 150 mg/kg (14)C-clopyralid. An additional 5 rats/sex were dosed daily with 5 mg/kg/day unlabeled clopyralid for 14 days, followed by a single treatment with 5 mg/kg/day of (14)C-clopyralid. No label was found in expired air. Tissue levels at 72 hour sacrifices were either very low (carcass or stomach) or non-detectable for the several treatment regiments. Generally, over 90% of label was found in urine collected within 24 hr, regardless of administration method. Small amounts of label (1-5%) were found in feces. An analysis of the only detectable urinary labeled fraction found this to be unaltered clopyralid.

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Metabolism / Metabolites
Groups of 5 Crl:CD (F-344) BR rats/sex were dosed with single iv treatments of (14)C-labeled clopyralid, either 5 mg/kg in saline, by single gavage doses of 5 or 150 mg/kg (14)C-clopyralid. An additional 5 rats/sex were dosed daily with 5 mg/kg/day unlabeled clopyralid for 14 days, followed by a single treatment with 5 mg/kg/day of (14)C-clopyralid. No label was found in expired air. Tissue levels at 72 hour sacrifices were either very low (carcass or stomach) or non-detectable for the several treatment regiments. Generally, over 90% of label was found in urine collected within 24 hr, regardless of administration method. Small amounts of label (1-5%) were found in feces. An analysis of the only detectable urinary labeled fraction found this to be unaltered clopyralid.

Toxicity Data
LC50 >1000 mg/m3

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Non-Human Toxicity Values
LD50 Rat male oral 4300 mg/kg
LD50 Rat ip 900 mg/kg
LD50 Rabbit percutaneous > 2000 mg/kg
LD50 Mice oral > 5000 mg/kg

Clopyralid is an organochlorine pesticide having a 3,6-dichlorinated picolinic acid structure. It has a role as a herbicide. It is a member of pyridines and an organochlorine pesticide. It is functionally related to a picolinic acid.
Clopyralid is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers. Clopyralid is in the picolinic acid family of herbicides, which also includes aminopyralid, picloram, triclopyr, and several less common herbicides. For control of Creeping Thistle, Cirsium arvense, a noxious, perennial weed, clopyralid is one of the few effective herbicides available. It is particularly damaging to peas, tomatoes and sunflowers and can render potatoes, lettuce and spinach inedible. It does not affect members of the family Poaceae (grasses).

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Mechanism of Action
Selective systemic herbicide, absorbed by the leaves and roots, with translocation both acropetally and basipetally, and accumulation in meristematic tissue. Exhibits an auxin type reaction. Acts on cell elongation and respiration.

C6H3CL2NO2

191.995

190.954

1702-17-6

15553

White crystalline solid
Colorless crystals

1.6±0.1 g/cm3

323.7±37.0 °C at 760 mmHg

151-152°C

149.6±26.5 °C

0.0±0.7 mmHg at 25°C

1.606

1.3

1

3

1

11

165

0

ClC1C([H])=C([H])C(=NC=1C(=O)O[H])Cl

HUBANNPOLNYSAD-UHFFFAOYSA-N

InChI=1S/C6H3Cl2NO2/c7-3-1-2-4(8)9-5(3)6(10)11/h1-2H,(H,10,11)

3,6-dichloropyridine-2-carboxylic acid

XRM-3972; XRM 3972; Clopyralid

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 : ~100 mg/mL (~520.83 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (13.02 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 (13.02 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in 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 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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Solubility in Formulation 3: ≥ 2.5 mg/mL (13.02 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (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 900 μL of corn oil and mix evenly.

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