D₂ Receptor ( Ki = 3.9 nM ); D₃ Receptor ( Ki = 0.5 nM ); D₄ Receptor ( Ki = 1.3 nM )

Pramipexole (0.25-1 mg/kg; i.p.) dramatically lowers the infarction volume in animals[5]. Pramipexole improves neurological recovery[5]. Pramipexole inhibits ischemic cell death through mitochondrial pathways in ischemic stroke[5].

The blood-brain barrier (BBB) transport of pramipexole, a potent dopamine receptor agonist with high efficacy for Parkinson's disease, was mainly characterized using immortalized rat brain capillary endothelial cells (RBEC)1 as an in vitro BBB model. [(14)C]Pramipexole uptake by RBEC1 was dependent on temperature and pH, but not sodium ion concentration or membrane potential. The uptake was inhibited by several organic cations including pyrilamine. Mutual inhibition was observed between pramipexole and pyrilamine. In addition, [(14)C]pramipexole uptake was stimulated by preloading unlabeled pramipexole. RT-PCR analysis for organic cation transporters (rOCT1-3, rOCTN1-2) in RBEC1 was performed. The mRNA level of rOCTN2 was the highest, followed by rOCTN1, while expression of rOCT1, rOCT2 and rOCT3 was negligible. The brain uptake of [(14)C]pramipexole, which was measured by the in situ rat brain perfusion technique, was significantly inhibited by unlabeled pramipexole. These results suggest that pramipexole is, at least in part, transported across the BBB by an organic cation-sensitive transporter. The pramipexole transport in RBEC1 was pH-dependent, but sodium- and membrane potential-independent[2].

The antiparkinsonian ropinirole and pramipexole are D3 receptor- (D3R-) preferring dopaminergic (DA) agonists used as adjunctive therapeutics for the treatment resistant depression (TRD). While the exact antidepressant mechanism of action remains uncertain, a role for D3R in the restoration of impaired neuroplasticity occurring in TRD has been proposed. Since D3R agonists are highly expressed on DA neurons in humans, we studied the effect of ropinirole and pramipexole on structural plasticity using a translational model of human-inducible pluripotent stem cells (hiPSCs). Two hiPSC clones from healthy donors were differentiated into midbrain DA neurons. Ropinirole and pramipexole produced dose-dependent increases of dendritic arborization and soma size after 3 days of culture, effects antagonized by the selective D3R antagonists SB277011-A and S33084 and by the mTOR pathway kinase inhibitors LY294002 and rapamycin. All treatments were also effective in attenuating the D3R-dependent increase of p70S6-kinase phosphorylation. Immunoneutralisation of BDNF, inhibition of TrkB receptors, and blockade of MEK-ERK signaling likewise prevented ropinirole-induced structural plasticity, suggesting a critical interaction between BDNF and D3R signaling pathways. The highly similar profiles of data acquired with DA neurons derived from two hiPSC clones underpin their reliability for characterization of pharmacological agents acting via dopaminergic mechanisms[3].

Male Wistar rats weighing 250-300 g (16-18 weeks old)
0.25 mg/kg, 1 mg/kg
Intraperitoneal injection

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A dopamine D2 receptor agonist, pramipexole, has been found to elicit neuroprotection in patients with Parkinson's disease and restless leg syndrome. Recent evidence has shown that pramipexole mediates its neuroprotection through mitochondria. Considering this, we examined the possible mitochondrial role of pramipexole in promoting neuroprotection following an ischemic stroke of rat. Male Wistar rats underwent transient middle cerebral artery occlusion (tMCAO) and then received pramipexole (0.25 mg and 1 mg/kg body weight) at 1, 6, 12 and 18 h post-occlusion. A panel of neurological tests and 2,3,5-triphenyl tetrazolium chloride (TTC) staining were performed at 24 h after the surgery. Flow cytometry was used to detect the mitochondrial membrane potential, and mitochondrial levels of reactive oxygen species (ROS) and Ca2+, respectively. Mitochondrial oxidative phosphorylation was analyzed by oxygraph (oxygen electrode). Western blotting was used to analyze the expression of various proteins such as Bax, Bcl-2 and cytochrome c Pramipexole promoted the neurological recovery as shown by the panel of neurobehavioral tests and TTC staining. Post-stroke treatment with pramipexole reduced levels of mitochondrial ROS and Ca2+ after ischemia. Pramipexole elevated the mitochondrial membrane potential and mitochondrial oxidative phosphorylation. Western blotting showed that pramipexole inhibited the transfer of cytochrome c from mitochondria to cytosol, and hence inhibited the mitochondrial permeability transition pore. Thus, our results have demonstrated that post-stroke administration of pramipexole induces the neurological recovery through mitochondrial pathways in ischemia/reperfusion injury[5].

Absorption, Distribution and Excretion
The bioavailability of pramipexole is higher than 90%, indicating a high level of absorption.
The main route of pramipexole elimination, with 90% of a pramipexole dose found in the urine, almost entirely as unchanged drug.
This drug is extensively distributed in the body with a volume of distribution of approximately 500 L.
Renal clearance is about 400 mL/min, indicating heavy secretion by the renal tubules.
Pramipexole is extensively distributed, having a volume of distribution of about 500 L. Protein binding is less than 20% in plasma; with albumin accounting for most of the protein binding in human serum. Pramipexole distributes into red blood cells as indicated by an erythrocyte to plasma ratio of approximately 2.0 and a blood to plasma ratio of approximately 1.5. Consistent with the large volume of distribution in humans, whole body autoradiography and brain tissue levels in rats indicated that pramipexole was widely distributed throughout the body, including the brain.
Urinary excretion is the major route of pramipexole elimination. Approximately 88% of a 14C-labelled dose was recovered in the urine and less than 2% in the faeces following single intravenous and oral doses in healthy volunteers. The terminal elimination half-life was about 8.5 hours in young volunteers (mean age 30 years) and about 12 hours in elderly volunteers (mean age 70 years). Approximately 90% of the recovered (14)C-labelled dose was unchanged drug; with no specific metabolites having been identified in the remaining 10% of the recovered radio-labelled dose. Pramipexole is the levorotational (-) enantiomer, and no measurable chiral inversion or racemization occurs in vivo.
Pramipexole is rapidly absorbed, reaching peak concentrations in approximately 2 hours. The absolute bioavailability of pramipexole is greater than 90%, indicating that it is well absorbed and undergoes little presystemic metabolism. Food does not affect the extent of pramipexole absorption, although the time of maximum plasma concentration (Tmax) is increased by about 1 hour when the drug is taken with a meal.
The objective of the study was to investigate the anodal iontophoretic delivery of pramipexole (PRAM), a dopamine agonist used for the treatment of Parkinson's disease, in order to determine whether therapeutic amounts of the drug could be delivered across the skin. Preliminary iontophoretic experiments were performed in vitro using porcine ear and human abdominal skin. These were followed by a pharmacokinetic study in male Wistar rats to determine the drug input rate in vivo. Stability studies revealed that after current application (0.5 mA/cm(2) for 6h), the solution concentration of PRAM was only 60.2 + or - 5.3% of its initial value. However, inclusion of sodium metabisulfite (0.5%), an antioxidant, increased this to 97.2 + or - 3.1%. Iontophoretic transport of PRAM across porcine skin in vitro was studied as a function of current density (0.15, 0.3, 0.5 mA/cm(2)) and concentration (10, 20, 40 mM). Increasing the current density from 0.15 to 0.3 and 0.5 mA/cm(2), resulted in 2.5- and 4-fold increases in cumulative permeation, from 309.5 + or - 80.2 to 748.8 + or - 148.1 and 1229.1 + or - 138.6 ug/sq cm, respectively. Increasing the PRAM concentration in solution from 10 to 20 and 40 mM resulted in a 2-fold increase in cumulative permeation (816.4 + or - 123.3, 1229.1 + or - 138.6 and 1643.6 + or - 201.3 u g/sq cm, respectively). Good linearity was observed between PRAM flux and both the applied current density (r(2)=0.98) and drug concentration in the formulation (r(2)=0.99). Co-iontophoresis of acetaminophen showed that electromigration was the dominant electrotransport mechanism (accounting for >80% of delivery) and that there was no inhibition of electroosmotic flow at any current density. Cumulative iontophoretic permeation across human and porcine skin (after 6 hr at 0.5 mA/sq cm) was also shown to be statistically equivalent (1229.1 + or- 138.6 and 1184.8 + or- 236.4 ug/sq cm, respectively). High transport and delivery efficiencies were achieved for PRAM (up to 7% and 58%, respectively). The plasma concentration profiles obtained in the iontophoretic studies in vivo (20 mM PRAM; 0.5 mA/sq cm for 5 hr) were modelled using constant and time-variant input models; the latter gave a superior quality fit. The drug input rate in vivo suggested that PRAM electrotransport rates would be sufficient for therapeutic delivery and the management of Parkinsonism.
For more Absorption, Distribution and Excretion (Complete) data for PRAMIPEXOLE (7 total), please visit the HSDB record page.

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Metabolism / Metabolites
This drug undergoes little metabolism in humans.
Pramipexole is metabolized only to a negligible extent (<10%). No specific active metabolite has been identified in human plasma or urine.
No metabolites have been identified in plasma or urine.
Route of Elimination: Urinary excretion is the major route of pramipexole elimination, with 90% of a pramipexole dose recovered in urine, almost all as unchanged drug. Nonrenal routes may contribute to a small extent to pramipexole elimination, although no metabolites have been identified in plasma or urine.
Half Life: 8 hours

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Biological Half-Life
About 8.5-12 hours.
The terminal elimination half-life was about 8.5 hours in young volunteers (mean age 30 years) and about 12 hours in elderly volunteers (mean age 70 years).

Toxicity Summary
IDENTIFICATION AND USE: Pramipexole, a synthetic benzothiazolamine derivative, is a nonergot-derivative dopamine receptor agonist. It is used for the symptomatic management of idiopathic parkinsonian syndrome. It is also used for the symptomatic management of moderate-to-severe primary restless legs syndrome. HUMAN EXPOSURE AND TOXICITY: There is no clinical experience with significant overdosage. One patient took 11 mg/day of pramipexole for 2 days in a clinical trial for an investigational use. Blood pressure remained stable although pulse rate increased to between 100 and 120 beats/minute. No other adverse reactions were reported related to the increased dose. Postmarketing reports with medication used to treat Parkinson's disease, including pramipexole, indicate that patients may experience new or worsening mental status and behavioral changes, which may be severe, including psychotic-like behavior during treatment with pramipexole or after starting or increasing the dose of pramipexole. Other drugs prescribed to improve the symptoms of Parkinson's disease can have similar effects on thinking and behavior. This abnormal thinking and behavior can consist of one or more of a variety of manifestations including paranoid ideation, delusions, hallucinations, confusion, psychotic-like behavior, disorientation, aggressive behavior, agitation, and delirium. Case reports and the results of a cross-sectional study suggest that patients can experience intense urges to gamble, increased sexual urges, intense urges to spend money uncontrollably, binge eating, and/or other intense urges and the inability to control these urges while taking one or more of the medications, including pramipexole, that increase central dopaminergic tone and that are generally used for the treatment of Parkinson's disease. In some cases, although not all, these urges were reported to have stopped when the dose was reduced or the medication was discontinued. ANIMAL STUDIES: Single dose toxicity of pramipexole after oral administration was studied in rodents, dogs and monkeys. In rodents, CNS-related signs at high doses included ataxia, dyspnea and tremor/convulsions. In dogs, vomiting occurred at 0.0007 mg/kg and above. Monkeys displayed major excitation at 3.5 mg/kg. Pramipexole was administered to mice for two years at drug in-diet-doses of 0.3, 2, or 10 mg/kg/day. With the exception of statistically significant decreases in adrenal cortical adenomas in males at 10 mg/kg and malignant lymphomas in females at 2 and 10 mg/kg, the incidence of neoplastic changes was similar in treated and control animals. Pramipexole was administered to rats for two years by drug-in-diet, at doses of 0.3, 2, or 8 mg/kg/day. A statistically significant increase in the incidence of Leydig cell adenomas was noted in males at 2 and 8 mg/kg. The following neoplasms were significantly decreased in rats at 2 and 8 mg/kg: mammary gland neoplasia in females, pituitary adenomas in both sexes, total number of primary neoplasms in females. Additionally, a decrease in the incidence of benign adrenal medullary neoplasms was observed in female rats at 0.3, 2, and 8 mg/kg/day. Although retinal degeneration was observed in albino rats given 2 or 8 mg/kg/day, no retinal degeneration was noted at the low dose of 0.3 mg/kg/day. No retinal degeneration was seen in the two year carcinogenicity study in mice, in the one year drug-in-diet rat study, or in any other study in any species. The treatment of albino rats with pramipexole clearly reduced the rate of disk shedding from photoreceptor cells. This change was associated with increased sensitivity of the retina of albino rats to the damaging effects of light. In contrast, pigmented rats had absolutely no degeneration of any portion of the retina. When pramipexole was given to female rats throughout pregnancy, implantation was inhibited at a dose of 2.5 mg/kg/. Administration of 1.5 mg/kg/day of pramipexole to pregnant rats during the period of organogenesis resulted in a high incidence of total resorption of embryos. These findings are thought to be due to the prolactin-lowering effect of pramipexole, since prolactin is necessary for implantation and maintenance of early pregnancy in rats (but not rabbits or humans). There was no evidence of adverse effects on embryo-fetal development following administration of up to 10 mg/kg/day to pregnant rabbits during organogenesis. Postnatal growth was inhibited in the offspring of rats treated with 0.5 mg/kg/day or greater during the latter part of pregnancy and throughout lactation. In rat fertility studies, pramipexole at a dose of 2.5 mg/kg/day, prolonged estrus cycles and inhibited implantation. Pramipexole was not mutagenic or clastogenic in a battery of in vitro (bacterial reverse mutation, V79/HGPRT gene mutation, chromosomal aberration in CHO cells) and in vivo (mouse micronucleus) assays.
The precise mechanism of action of Pramipexole as a treatment for Parkinson's disease is unknown, although it is believed to be related to its ability to stimulate dopamine receptors in the striatum.

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Hepatotoxicity
Pramipexole has been reported to cause serum aminotransferase elevations in a small proportion of patients, but these abnormalities are usually mild, asymptomatic and self-limiting even without dose adjustment. Pramipexole has not been implicated in cases of clinically apparent acute liver injury which must be rare, if it occurs at all.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the use of pramipexole during breastfeeding, but it suppresses serum prolactin and may interfere with breastfeeding. An alternate drug may be preferred, especially while nursing a newborn or preterm infant.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information in nursing mothers was not found as of the revision date. Pramipexole lowers serum prolactin.[1] The prolactin level in a mother with established lactation may not affect her ability to breastfeed.

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Protein Binding
About 15% bound to plasma proteins.

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Interactions
Because of possible additive effects, caution should be advised when patients are taking other sedating medication or alcohol in combination with Mirapex and when taking concomitant medication that increase plasma levels of pramipexole (e.g. cimetidine).
Concomitant therapy with drugs secreted by the renal cationic transport system (e.g., amantadine, cimetidine, ranitidine, diltiazem, triamterene, verapamil, quinidine, and quinine), may decrease the oral clearance of Mirapex and thus, may necessitate an adjustment in the dosage of Mirapex. In case of concomitant treatment with these kinds of drugs (incl. amantadine) attention should be paid to signs of dopamine overstimulation, such as dyskinesias, agitation or hallucinations. In such cases a dose reduction is necessary. Concomitant therapy with drugs secreted by the renal anionic transport system (e.g., cephalosporins, penicillins, indomethacin, hydrochlorothiazide and chlorpropamide) are not likely to have any effect on the oral clearance of Mirapex.
Cimetidine, a known inhibitor of renal tubular secretion of organic bases via the cationic transport system, increased Mirapex AUC by 50% and increased its half-life by 40% in volunteers (N = 12).
In volunteers (N = 11), selegiline did not influence the pharmacokinetics of pramipexole. Population pharmacokinetic analysis suggests that amantadine may alter the oral clearance of pramipexole (N = 54). Levodopa/carbidopa did not influence the pharmacokinetics of pramipexole in volunteers (N = 10). Pramipexole did not alter the extent of absorption (AUC) or elimination of levodopa/carbidopa, although it increased levodopa Cmax by about 40%, and decreased Tmax from 2.5 to 0.5 hours. While increasing the dose of Mirapex in Parkinson's disease patients it is recommended that the dosage of levodopa is reduced and the dosage of other antiparkinsonian medication is kept constant.
Since pramipexole is a dopamine agonist, it is possible that dopamine antagonists, such as the neuroleptics (phenothiazines, butyrophenones, thioxanthenes) or metoclopramide, may diminish the effectiveness of Mirapex tablets.

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Non-Human Toxicity Values
LD50 Rat iv 210 mg/kg
LD50 Rat (female) oral >548 mg/kg
LD50 Rat (male) oral >800 mg/kg
LD50 Mouse (female) iv 188.3 (151.9-194.9) mg/kg
For more Non-Human Toxicity Values (Complete) data for PRAMIPEXOLE (6 total), please visit the HSDB record page.

[1]. A review of the receptor-binding and pharmacokinetic properties of dopamine agonists. Clin Ther, 2006. 28(8): p. 1065-78.

[2]. Blood-brain barrier transport of pramipexole, a dopamine D2 agonist. Life Sci. 2007 Apr 3;80(17):1564-71.

[3]. Ropinirole and Pramipexole Promote Structural Plasticity in Human iPSC-Derived Dopaminergic Neurons via BDNF and mTOR Signaling. Neural Plast. 2018; 2018: 4196961.

[4]. Attenuation of levodopa-induced toxicity in mesencephalic cultures by pramipexole. J Neural Transm (Vienna). 1997;104(2-3):209-28.

[5]. Pramipexole prevents ischemic cell death via mitochondrial pathways in ischemic stroke. Dis Model Mech. 2019 Aug 1; 12(8): dmm033860.

Therapeutic Uses
Antioxidants; Antiparkinson Agents; Dopamine Agonists
/CLINICAL TRIALS/ ClinicalTrials.gov is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world. The Web site is maintained by the National Library of Medicine (NLM) and the National Institutes of Health(NIH). Each ClinicalTrials.gov record presents summary information about a study protocol and includes the following: Disease or condition; Intervention (for example, the medical product, behavior, or procedure being studied); Title, description, and design of the study; Requirements for participation (eligibility criteria); Locations where the study is being conducted; Contact information for the study locations; and Links to relevant information on other health Web sites, such as NLM's MedlinePlus for patient health information and PubMed for citations and abstracts for scholarly articles in the field of medicine. Pramipexole is included in the database.
Mirapex tablets are indicated for the treatment of moderate-to-severe primary Restless Legs Syndrome (RLS). /Included in US product label/
Mirapex tablets are indicated for the treatment of Parkinson's disease. /Included in US product label/
For more Therapeutic Uses (Complete) data for PRAMIPEXOLE (7 total), please visit the HSDB record page.

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Drug Warnings
Postmarketing reports with medication used to treat Parkinson's disease, including Mirapex, indicate that patients may experience new or worsening mental status and behavioral changes, which may be severe, including psychotic-like behavior during treatment with Mirapex or after starting or increasing the dose of Mirapex. Other drugs prescribed to improve the symptoms of Parkinson's disease can have similar effects on thinking and behavior. This abnormal thinking and behavior can consist of one or more of a variety of manifestations including paranoid ideation, delusions, hallucinations, confusion, psychotic-like behavior, disorientation, aggressive behavior, agitation, and delirium.
Patients with a major psychotic disorder should ordinarily not be treated with dopamine agonists, including Mirapex, because of the risk of exacerbating the psychosis. In addition, certain medications used to treat psychosis may exacerbate the symptoms of Parkinson's disease and may decrease the effectiveness of Mirapex.
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from Mirapex, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
There are no adequate and well-controlled studies in pregnant women. Mirapex should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
For more Drug Warnings (Complete) data for PRAMIPEXOLE (13 total), please visit the HSDB record page.

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Pharmacodynamics
**Parkinson's Disease** Through the stimulation of dopamine receptors, pramipexole is thought to relieve the symptoms of Parkinson's Disease. The motor symptoms of Parkinson's disease occur partly due to a reduction of dopamine in the substantia nigra of the brain. Dopamine is an essential neurotransmitter that has major effects on motor movements in humans. **Restless Legs Syndrome** Pramipexole likely restores balance to the dopaminergic system, controlling the symptoms of this condition. Restless legs syndrome is thought to occur, in part, through dysfunction of the dopaminergic system, resulting in unpleasant lower extremity symptoms,. **Other effects** In addition to the abovementioned effects, animal studies demonstrate that pramipexole blocks dopamine synthesis, release, and turnover. Additionally, this drug is neuroprotective to dopamine neuron degeneration after ischemia or methamphetamine neurotoxicity.

C10H17N3S

211.33

211.114

C, 56.84; H, 8.11; N, 19.88; S, 15.17

104632-26-0

Pramipexole dihydrochloride; 104632-25-9; Dexpramipexole dihydrochloride; 104632-27-1; Pramipexole dihydrochloride hydrate; 191217-81-9; Dexpramipexole;104632-28-2; Pramipexole-d5; 1217975-28-4

119570

White to off-white solid powder

1.2±0.1 g/cm3

378.0±42.0 °C at 760 mmHg

288-290°C

182.4±27.9 °C

0.0±0.9 mmHg at 25°C

1.583

1.42

2

4

3

14

188

1

S1C(N([H])[H])=NC2=C1C([H])([H])[C@]([H])(C([H])([H])C2([H])[H])N([H])C([H])([H])C([H])([H])C([H])([H])[H]

FASDKYOPVNHBLU-ZETCQYMHSA-N

InChI=1S/C10H17N3S/c1-2-5-12-7-3-4-8-9(6-7)14-10(11)13-8/h7,12H,2-6H2,1H3,(H2,11,13)/t7-/m0/s1

(6S)-6-N-propyl-4,5,6,7-tetrahydro-1,3-benzothiazole-2,6-diamine

2934.99.03.00

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)

Solubility in Formulation 1: 10 mg/mL (47.32 mM) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 100.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (11.83 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 3: ≥ 2.5 mg/mL (11.83 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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 (Please use freshly prepared in vivo formulations for optimal results.)