Bifenthrin suppresses A. gambiae as well as C. quinquefasciatus, whose respective LD50 values are 0.15 and 0.16 ng/mg[1]. Filter paper treated with benthrin and subjected to C. Only doses of 0.5% and 0.125%, respectively, of quinquefasciatus and A gambiae tarsi can result in 100% mortality [1].

Absorption, Distribution and Excretion
Male and female rats were treated with (14)C-bifenthrin labeled in the acid or alcohol moiety at single oral doses of 4 and 35 mg/kg. (14)C was rapidly excreted into feces and urine, and the excretion rates of the (14)C to feces and urine were 66-83% and 13-25%, respectively. Highest residues were found in the fat, with values of slightly more than 1 ppm after low-dose administration and 8 and 16 ppm in males and females, respectively, after application of the high dose. Residue levels in other organs were in most cases <0.2 ppm after low-dose administration and <1 ppm after high-dose administration.
The tissue residues /of rats/ were examined after oral administration of (14)C-bifenthrin at 0.5 mg/kg/day for 70 days. The peak (14)C concentrations on an average were 9.6 ppm in fat, 1.7 ppm in skin, 0.4 ppm in liver, 0.3 ppm in kidney, 1.7 ppm in ovaries, 3.2 ppm in sciatic nerve, 0.06 ppm in whole blood, and 0.06 ppm in plasma. Analyses were extended for an additional 85 days following cessation of dosing (depuration phase). Half-lives of 51 days (fat), 50 days (skin), 19 days (liver), 28 days (kidney), and 40 days (ovaries and sciatic nerve) were estimated from (14)C-depuration. Analysis of the fat revealed that the parent chemical accounted for a majority (65-85%) of the (14)C-residues in fat.
Pyrethrins are absorbed through intact skin when applied topically. /Pyrethrins/
... The pharmacokinetics of bifenthrin in the rat after oral, inhalation and intravenous administration is described. Pyrethroid acute toxicity via oral and inhalation routes is also presented. Groups of male rats were dosed by oral gavage at 3.1 mg/kg in 1 mL/kg of corn oil (the critical, acute, oral benchmark dose lower limit, BMDL) and at an equivalent dose by inhalation (0.018 mg/L) for 4 hr. At 2, 4, 6, 8 and 12 hr after dosing initiation, blood plasma and brain bifenthrin concentrations were measured. The maximum concentrations of bifenthrin in plasma were 361 ng/mL or 0.853 uM (oral) and 232 ng/mL or 0.548 uM (inhalation), and in brain they were 83 and 73 ng/g. The area under the concentration versus time curve (AUC) values were 1969 h ng/mL (plasma) and 763 h ng/mL (brain) following oral gavage dosing, and 1584 h ng/mL (plasma) and 619 h ng/mL (brain) after inhalation. Intravenous dosing resulted in apparent terminal half-life (t1/2 ) values of 13.4 h (plasma) and 11.1 h (brain) and in AUC0-infinity values of 454 and 1566 h ng/mL for plasma and brain. Clearance from plasma was 37 mL/min/kg. Peak plasma and brain concentrations were generally a little higher after oral dosing (by ca 14%). Inhalation administration of bifenthrin did not cause increases in exposure in plasma or brain by avoiding first-pass effects in the liver. The elimination t1/2 was comparable with other pyrethroids and indicated little bioaccumulation potential. ...
... This study evaluated the oral disposition and bioavailability of bifenthrin in the adult male Long-Evans rat. In the disposition study, rats were administered bifenthrin (0.3 or 3 mg/kg) by oral gavage and serially sacrificed (0.25 hr to 21 days). Blood, liver, brain and adipose tissue were removed. In the bioavailability study, blood was collected serially from jugular vein cannulated rats (0.25 to 24 hr) following oral (0.3 or 3 mg/kg) or intravenous (0.3 mg/kg) administration of bifenthrin. Tissues were extracted and analyzed for bifenthrin by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Bifenthrin concentration in blood and liver peaked 1-2-hr post-oral administration and were approximately 90 ng/mL (or g) and 1000 ng/mL (or g) for both tissues at 0.3 and 3 mg/kg, respectively. Bifenthrin was rapidly cleared from both blood and liver. Brain concentrations peaked at 4-6 hr and were lower than in blood at both doses (12 and 143 ng/g). Bifenthrin in adipose tissue peaked at the collected time points of 8 (157 ng/g) and 24 (1145 ng/g) hr for the 0.3 and 3 mg/kg doses, respectively and was retained 21 days post-oral administration. Following intravenous administration, the blood bifenthrin concentration decreased bi-exponentially, with a distribution half-life of 0.2 hr and an elimination half-life of 8 hr. Bifenthrin bioavailability was approximately 30%. These disposition and kinetic bifenthrin data may decrease uncertainties in the risk assessment for this pyrethroid insecticide.

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Metabolism / Metabolites
Male and female rats were treated with (14)C-bifenthrin labeled in the acid or alcohol moiety at single oral doses of 4 and 35 mg/kg. (14)C was rapidly excreted into feces and urine, and the excretion rates of the (14)C to feces and urine were 66-83% and 13-25%, respectively. ... The major fecal metabolites possessed intact ester linkage hydroxylated in the acid or alcohol moiety such as hydroxymethyl-bifenthrin, 4'-OH-bifenthrin, and 3'- or 4'-OH-hydroxymethyl bifenthrin. Ester-cleaved products derived from mono- and dihydroxylated parent compounds were also detected. On the other hand, the majority of urinary metabolites were ester-cleaved products such as 4'-OH-BPacid (4'-hydroxy-2-methyl-3-phenylbenzoic acid), BPacid (2-methyl-3-phenylbenzoic acid), 4'-OH-BPalcohol (4'-hydroxy-2-methyl-3-phenylbenzyl alcohol), dimethoxy-BPacid, 4'-methoxy BPacid, dimethoxy BPalcohol, BPalcohol, TFPacid [3-(2-chloro-3,3,3-trifluoro-1-propenyl-2,2-dimethyl-cyclopropanecarboxylic acid], cis- and trans-hydroxymethyl TFPacid. The major metabolic pathways are considered to be hydrolysis of ester linkage, oxidation at the methyl group of the acid moiety and at the 3'- and 4'-positions of the phenyl group, and O-methylation. The conjugation reactions are considered to take place; however, detailed information is not available.
Fastest breakdown is seen with primary alcohol esters of trans-substituted acids since they undergo rapid hydrolytic and oxidative attack. For all secondary alcohol esters and for primary alcohol cis-substituted cyclopropanecarboxylates, oxidative attack is predominant. /Pyrethroids/
Pyrethrins are reportedly inactivated in the GI tract following ingestion. In animals, pyrethrins are rapidly metabolized to water soluble, inactive compounds. /Pyrethrins/
Bifenthrin, a pyrethroid pesticide, is estrogenic in vivo in fishes. However, bifenthrin is documented to be anti-estrogenic in vitro, in the ER-CALUX (estrogen receptor) cell line. We investigated whether metabolite formation is the reason for this incongruity. We exposed Menidia beryllina (inland silversides) to 10 ng/L bifenthrin, 10 ng/L 4-hydroxy bifenthrin, and 10 ng/L bifenthrin with 25 ug/L piperonyl butoxide (PBO) - a P450 inhibitor. Metabolite-exposed juveniles had significantly higher estrogen-mediated protein levels (choriogenin) than bifenthrin/PBO-exposed, while bifenthrinalone was intermediate (not significantly different from either). This suggests that metabolites are the main contributors to bifenthrin's in vivo estrogenicity.
Synthetic pyrethroids are generally metabolized in mammals through ester hydrolysis, oxidation, and conjugation, and there is no tendency to accumulate in tissues. In the environment, synthetic pyrethroids are fairly rapidly degraded in soil and in plants. Ester hydrolysis and oxidation at various sites on the molecule are the major degradation processes. /Pyrethroids/

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Biological Half-Life
The tissue residues /of rats/ were examined after oral administration of (14)C-bifenthrin at 0.5 mg/kg/day for 70 days. ... Analyses were extended for an additional 85 days following cessation of dosing (depuration phase). Half-lives of 51 days (fat), 50 days (skin), 19 days (liver), 28 days (kidney), and 40 days (ovaries and sciatic nerve) were estimated from (14)C-depuration.
... Intravenous dosing resulted in apparent terminal half-life (t1/2 ) values of 13.4 hr (plasma) and 11.1 hr (brain) ... .
... Following intravenous administration, the blood bifenthrin concentration decreased bi-exponentially, with a distribution half-life of 0.2 hr and an elimination half-life of 8 hr. ...

Toxicity Summary
IDENTIFICATION AND USE: Bifenthrin is a light brown viscous oil. Bifenthrin is registered for use to control a variety of insects including aphids, worms, ants, gnats, moths, beetles, grasshoppers, mites, midges, spiders, ticks, yellow jackets, maggots, thrips, caterpillars, flies, fleas, and other pests in domestic, public health, agricultural, and industrial situations. HUMAN EXPOSURE AND TOXICITY: Neurological effects include symptoms such as dizziness, headache, tingling and numbness sensation, muscle spasms and tremors. Dermal effects include symptoms such as rash, hives, blisters, sores and itchiness. Respiratory effects include symptoms such as: shortness of breath, asthma, respiratory distress, respiratory irritation, coughing, difficulty in breathing, sinus problems, and chest pain. Most of the gastrointestinal symptoms were nausea, vomiting and few cases presented with abdominal pain and diarrhea. Ocular symptoms were redness, pain and swelling of eyes, itchy watery eyes and blurred vision. Few cases presented with cardiovascular symptoms such as high blood pressure, irregular heartbeat, and heart attack. Exposure to bifenthrin, even at "acceptable" limits, can increase the risk for and frequency of inflammatory responses and diseases such as asthma. ANIMAL STUDIES: Non-irritant to skin; virtually non-irritating to eyes (rabbits); no skin sensitization (guinea pigs). Bifenthrin Technical, 88.35% a.i., 98% cis, 2% trans; 200, 100, 50, 12 and 0 ppm /was given to rats in feed; 50/sex/dose for 2 years. No oncogenic effects reported. Effects included tremors, abrasions, alopecia, tail lacerations, reduced weight gain (females only), and reduced RBC 12% (males only). All effects were observed at 200 ppm. Technical (Bifenthrin), 89.7%, administered to 4 Beagles/sex/group at nominal concentrations of 0, 0.75, 1.50, 3.0, and 5.0 mg/kg/day in gelatin capsules for 52 weeks; Intermittent delayed onset of tremors occurring through week 29 at 3.0 and 5.0 mg/kg/day. Bifenthrin technical, 88.35% a.i., 98% cis, 2% trans; 100, 60, 30 and 0 ppm was given to rats in the feed for 8 weeks prior to F0 mating through F2b weaning; 25/sex/dose; no fertility or reproductive effects, other effects include tremors during lactation, ovary weight reduction in adults. Non-teratogenic in rats (> or = 2 mg/kg/day) & rabbits (8 mg/kg/day). Tremors were observed in 6 pups out of 40 examined (4 males on post-natal day (PND) 10 and 2 females on PND 28) at the highest dose (9 mg/kg/day). Bifenthrin was not mutagenic in the Ames assay, and did not produce chromosome aberrations in Chinese hamster ovary (CHO) cells. ECOTOXICITY STUDIES: Based on available data, bifenthrin has been classified as slightly toxic on an acute basis to birds. Bifenthrin showed no adverse effects to reproduction at the highest concentration tested for birds. Mammalian toxicity data suggest that this compound is moderately toxic to small mammals on an acute basis. Relative to steelhead, rainbow trout have different responses to bifenthrin acute toxicity as well as different rates of hepatic bifenthrin biotransformation. Bifenthrin is highly toxic on an acute and chronic basis to freshwater fish and aquatic-phase amphibians, and very highly toxic to freshwater aquatic invertebrates. Bifenthrin has also been classified as very highly toxic to estuarine/marine fish and invertebrates on an acute basis.

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Interactions
A novel two-tiered analytical approach was used to characterize and quantify interactions between Type I and Type II pyrethroids on Hyalella azteca using standardized water column toxicity tests. Bifenthrin, permethrin, cyfluthrin and lambda-cyhalothrin were tested in all possible binary combinations across six experiments. All mixtures were analyzed for 4 d lethality, and two of the six mixtures (permethrin-bifenthrin and permethrin-cyfluthrin) were tested for subchronic 10 d lethality and sublethal effects on swimming motility and growth. Mixtures were initially analyzed for interactions using regression analyses, and subsequently compared to the additive models of Concentration Addition (CA) and Independent Action (IA) to further characterize mixture responses. Negative interactions (antagonistic) were significant in two of the six mixtures tested, including cyfluthrin-bifenthrin and cyfluthrin-permethrin, but only on the acute 4d lethality endpoint. In both cases mixture responses fell between the additive models of CA and IA. All other mixtures were additive across 4 d lethality, and bifenthrin-permethrin and cyfluthrin-permethrin were also additive on subchronic 10 d lethality and sublethal responses.
Piperonyl butoxide ... potentiates /insecticidal activity/ of pyrethrins by inhibiting the hydrolytic enzymes responsible for pyrethrins' metabolism in arthropods. When piperonyl butoxide is combined with pyrethrins, the insecticidal activity of the latter drug is increased 2-12 times /Pyrethrins/
At dietary level of 1000 ppm pyrethrins & 10000 ppm piperonyl butoxide ... /enlargement, margination, & cytoplasmic inclusions in liver cells of rats/ were well developed in only 8 days, but ... were not maximal. Changes were proportional to dosage & similar to those produced by DDT. Effects of the 2 ... were additive. /Pyrethrins/
Three carbamate (formetanate, methomyl, pyrimicarb) and one pyrethroid (bifenthrin) insecticides were investigated both as pure chemicals and as commercial formulations in order to unveil possible toxic effects of additives and solvents present in the commercial formulations and to evaluate the cellular stress response as a defense mechanism. Toxic effects were evaluated on A549 cells, derived from a human lung carcinoma, by measuring (1) threshold concentrations leading to a decrease of the growth rate (LOEC), (2) sublethal concentrations (SC) which arrested growth without killing the cells, and (3) expression levels of several stress proteins, i.e., HSP27, HSP72/73, HSP90, GRP78, and GRP94. As compared to the pure active molecule, LOEC appeared at lower concentrations when using the commercial formulations, i.e., Dicarzol (formetanate), Lannate20 (methomyl) and Talstar or Kiros EV (bifenthrin). Propylene glycol and propylene glycol monomethyl ether, respectively, present in Talstar and kiros, do not account for the high toxicity of these commercial formulations and do not potentiate the toxicity of bifenthrin. Additive but not synergistic adverse effects were observed when cells are exposed to a mixture of 4 different commercial formulations ... GRP78 was up-regulated by all the insecticides, commercial preparations being more efficient to trigger the stress reaction. This suggests that insecticides and additives present in commercial formulations disrupt ER functions. Conversely, HSP72/73 was found to be down-regulated by all the insecticides. This seems to be related with a decrease of protein synthesis in the cytosol, as a result of the ER unfolded protein response. Indeed, tunicamycin, known to inhibit N-linked glycosylation in the ER, was found to induce a similar inverse correlation between GRP78 overexpression and HSP72/73 under-expression. Expression of GRP94 was found to be increased and HSP27 lowered by the highest concentrations of bifenthrin commercial formulations. Methomyl and Lannate20 only induced an under-expression of HSP90.

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Non-Human Toxicity Values
LD50 Rat oral 375 mg/kg
LD50 Rat oral 54.5 mg/kg
LD50 Quail oral 1800 mg/kg
LD50 Duck oral >4450 mg/kg
LD50 Rabbit dermal >2000 mg/kg

[1]. Bifenthrin: a useful pyrethroid insecticide for treatment of mosquito nets. J Med Entomol. 2002 May;39(3):526-33.

[2]. Structure-activity relationships for the action of 11 pyrethroid insecticides on rat Na v 1.8 sodium channels expressed in Xenopus oocytes. Toxicol Appl Pharmacol. 2006 Mar 15;211(3):233-44.

Bifenthrin is an off-white to pale tan waxy solid with a very faint slightly sweet odor. Used as a broad spectrum insecticide.
Bifenthrin is a carboxylic ester obtained by formal condensation of cis-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylic acid and [(2-methyl-1,1'-biphenyl)-3-yl]methanol. It has a role as a pyrethroid ester insecticide and a pyrethroid ester acaricide. It is an organochlorine compound, an organofluorine compound and a cyclopropanecarboxylate ester. It is functionally related to a cis-chrysanthemic acid.
Bifenthrin is under investigation in clinical trial NCT01560247 (Percutaneous Recanalization in Ischemic Stroke Management in Europe Observational Registry).
See also: ... View More ...

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Mechanism of Action
Bifenthrin, a relatively stable type I pyrethroid that causes tremors and impairs motor activity in rodents, is broadly used. We investigated whether nanomolar bifenthrin alters synchronous Ca2+ oscillations (SCOs) necessary for activity-dependent dendritic development. Primary mouse cortical neurons were cultured 8 or 9 days in vitro (DIV), loaded with the Ca2+ indicator Fluo-4, and imaged using a Fluorescence Imaging Plate Reader Tetra. Acute exposure to bifenthrin rapidly increased the frequency of SCOs by 2.7-fold (EC50 = 58 nM) and decreased SCO amplitude by 36%. Changes in SCO properties were independent of modifications in voltage-gated sodium channels since 100 nM bifenthrin had no effect on the whole-cell Na+ current, nor did it influence neuronal resting membrane potential. The L-type Ca2+ channel blocker nifedipine failed to ameliorate bifenthrin-triggered SCO activity. By contrast, the metabotropic glutamate receptor (mGluR)5 antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine] normalized bifenthrin-triggered increase in SCO frequency without altering baseline SCO activity, indicating that bifenthrin amplifies mGluR5 signaling independent of Na+ channel modification. Competitive [AP-5; (-)-2-amino-5-phosphonopentanoic acid] and noncompetitive (dizocilpine, or MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]) N-methyl-d-aspartate antagonists partially decreased both basal and bifenthrin-triggered SCO frequency increase. Bifenthrin-modified SCO rapidly enhanced the phosphorylation of cAMP response element-binding protein (CREB). Subacute (48 hours) exposure to bifenthrin commencing 2 DIV-enhanced neurite outgrowth and persistently increased SCO frequency and reduced SCO amplitude. Bifenthrin-stimulated neurite outgrowth and CREB phosphorylation were dependent on mGluR5 activity since MPEP normalized both responses. Collectively these data identify a new mechanism by which bifenthrin potently alters Ca2+ dynamics and Ca2+-dependent signaling in cortical neurons that have long term impacts on activity driven neuronal plasticity.
Bifenthrin, a pyrethroid pesticide, is estrogenic in vivo in fishes. However, bifenthrin is documented to be anti-estrogenic in vitro, in the ER-CALUX (estrogen receptor) cell line. We investigated whether metabolite formation is the reason for this incongruity. We exposed Menidia beryllina (inland silversides) to 10 ng/L bifenthrin, 10 ng/L 4-hydroxy bifenthrin, and 10 ng/L bifenthrin with 25 ug/L piperonyl butoxide (PBO) - a P450 inhibitor. Metabolite-exposed juveniles had significantly higher estrogen-mediated protein levels (choriogenin) than bifenthrin/PBO-exposed, while bifenthrinalone was intermediate (not significantly different from either). This suggests that metabolites are the main contributors to bifenthrin's in vivo estrogenicity.
Voltage-gated sodium channels are important sites for the neurotoxic actions of pyrethroid insecticides in mammals. Here, we studied the mode of action of bifenthrin on the native sodium channels in cerebral cortical neurons prepared from newborn rat brain, where the toxic effects are largely generated. Bifenthrin caused a pronounced late current that persisted at the end of a depolarizing pulse, a slowly-decaying tail current following repolarization and significant resting modification (25.3% modification at 10 uM). No significant bifenthrin-induced effect was observed at the peak current. Bifenthrin also caused a concentration-dependent hyperpolarizing shift in steady-state activation and inactivation as well as slowed recovery from channel inactivation. Repetitive depolarization increased the potency of bifenthrin with high frequency. There was approximately 64% inhibition of modification upon repetitive activation by 10-Hz trains of depolarizing pulses. These results suggest that bifenthrin binds to and modifies sodium channels in both the closed and open states and exhibits the behavior between type I and type II.
... Since dopaminergic signaling significantly influences gonadotropin releasing hormone (GnRH2) release in fish, the goal of the study was to determine the effect of a 96 hr and 2 weeks exposure to bifenthrin on dopaminergic signaling in juvenile rainbow trout (Oncorhynchus mykiss) (RT). Our results indicated that a decrease in dopamine receptor 2A (DR2A) expression was associated with a trend toward an increase in plasma 17beta-estradiol (E2) following exposure at 96 hr and 2 weeks, and a significant increase in the relative expression of vitellogenin mRNA at 2 weeks. DR2A mRNA expression decreased 426-fold at 96 hr and 269-fold at 2 weeks in the brains of 1.5 ppb (3.55 pM) bifenthrin treated RT. There was an increase in tyrosine hydroxylase transcript levels at 96 hr, which is indicative of dopamine production in the brains of the 1.5 ppb (3.55 pM) bifenthrin treated RT. A significant increase in the relative expression of GnRH2 was observed at 96 hr but a significant decrease was noted after 2 weeks exposure indicating potential feedback loop activation. These results indicate that the estrogenic-effects of bifenthrin may result in part from changes in signaling within the dopaminergic pathway, but that other feedback pathways may also be involved.
For more Mechanism of Action (Complete) data for Bifenthrin (9 total), please visit the HSDB record page.

C23H22CLF3O2

422.87

422.126

82657-04-3

6442842

White to off-white solid powder

1.3±0.1 g/cm3

453.2±45.0 °C at 760 mmHg

68-71°C

136.5±17.9 °C

0.0±1.1 mmHg at 25°C

1.564

7.3

0

5

6

29

622

2

CC1=C(C=CC=C1C2=CC=CC=C2)COC(=O)[C@@H]3[C@@H](C3(C)C)/C=C(/C(F)(F)F)\Cl

OMFRMAHOUUJSGP-IRHGGOMRSA-N

InChI=1S/C23H22ClF3O2/c1-14-16(10-7-11-17(14)15-8-5-4-6-9-15)13-29-21(28)20-18(22(20,2)3)12-19(24)23(25,26)27/h4-12,18,20H,13H2,1-3H3/b19-12-/t18-,20-/m0/s1

(2-methyl-3-phenylphenyl)methyl (1R,3R)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropane-1-carboxylate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: This product requires protection from light (avoid light exposure) during transportation and storage.

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 (236.48 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (5.91 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 (5.91 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.)