5-HT₃ Receptor

Absorption, Distribution and Excretion
Orally-administered dolasetron is well absorbed, but the parent drug is rarely detected in plasma due to rapid and complete metabolism to hydrodolasetron.
Orally-administered dolasetron intravenous solution and tablets are bioequivalent.
The apparent absolute bioavailability of oral dolasetron is approximately 75%. Food does not affect the bioavailability of dolasetron taken by mouth.
Time to peak plasma concentration /for hydrodolasetron/ following oral administration /was/ approximately 1 hour and following intravenous injection /was/ 0.6 hours.
For more Absorption, Distribution and Excretion (Complete) data for DOLASETRON (15 total), please visit the HSDB record page.

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Metabolism / Metabolites
Biotransformation /is/ hepatic and complete, mainly to the active metabolite hydrodolasetron (by means of the ubiquitous enzyme, carbonyl reductase). Further hydroxylation is mediated by cytochrome P450 CYP2D6 and further N-oxidation by both CYP3A and flavin monooxygenase.
The metabolism of dolasetron mesylate was studied in six healthy male volunteers who were given a single 300 mg oral dose of [14C]dolasetron mesylate. An average of 59% of the total radioactivity was recovered in the urine and 25% in the feces. Metabolites were quantitated in urine samples taken up to 36 hr post-dose. Reduced dolasetron (RD) accounted for 17-54% of the dose in urine. Hydroxylated metabolites of RD made up no more than 9% of the dose in urine. Most of the remaining urinary radioactivity consisted of conjugated metabolites of RD and hydroxy RD. Hydrolysis of selected urine samples showed that the glucuronide of RD was the most abundant conjugate in urine. A small percentage of the dose (< 1%) in urine was identified as the N-oxide of RD. Analysis of urine samples by chiral HPLC indicated that the R(+):S(-) ratio of RD was approximately 9:1.
The initial step in the metabolism of dolasetron or MDL 73,147EF [(2 alpha, 6 alpha, 8 alpha, 9a beta)-octahydro-3-oxo-2,6-methano-2H- quinolizin-8-yl 1H-indol-3-carboxylate, monomethanesulfonate] is the reduction of the prochiral carbonyl group to give a chiral secondary alcohol "reduced dolasetron." An HPLC method, using a chiral column to separate reduced dolasetron enantiomers, has been developed and used to measure enantiomers in urine of rats, dogs, and humans after dolasetron administration. In all cases, the reduction was enantioselective for the (+)-(R)-enantiomer, although the dog showed lower stereoselectivity, especially after iv administration. An approximate enantiomeric ratio (+/-) of 90:10 was found in rat and human urine. The contribution of further metabolism to this enantiomeric ratio was considered small as preliminary studies showed that oxidation of the enantiomeric alcohols by human liver microsomes demonstrated only minor stereoselectivity. Further evidence for the role of stereoselective reduction in man was obtained from in vitro studies, where dolasetron was incubated with human whole blood. The enantiomeric composition of reduced dolasetron formed in human whole blood was the same as that found in human urine after administration of dolasetron. Enantioselectivity was not due to differences in the absorption, distribution, metabolism, or excretion of enantiomers, as iv or oral administration of rac-reduced dolasetron to rats and dogs lead to the recovery, in urine, of essentially the same enantiomeric composition as the dose administered. It is fortuitous that the (+)-(R)-enantiomer is predominantly formed by carbonyl reductase, as it is the more active compound.
Dolasetron has known human metabolites that include Reduced dolasetron.

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Biological Half-Life
Following oral administration hydrodolasetron has a elimination half-life of 8.1 hours (mean). Following intravenous injection dolasetron /has a elimination half-life of/ less than 10 minutes. Hydrodolasetron /has a elimination half-life of/ 7.3 hours after intravenous injection of dolasetron.
Following intravenous administration to healthy male subjects of doses ranging from 0.6 to 5 mg/kg, dolasetron disappeared extremely rapidly from plasma; concentrations were generally measurable for only 2-4 hr. Less than 1 percent of the dose was excreted intact in urine. A major plasma metabolite, reduced dolasetron, peaked rapidly at approximately 0.625 hr (median). Its median terminal disposition half-life was 7.56 hr ...

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Little information is available on the use of dolasetron during breastfeeding. Until more data become available, dolasetron should be used with caution during breastfeeding. An alternate drug may be preferred.
◉ Effects in Breastfed Infants
A double-blind study randomized 160 women receiving an elective cesarean section under spinal anesthesia to receive either sufentanil for patient-controlled intravenous analgesia (standard care) or standard care plus dexmedetomidine. Dexmedetomidine was given as 5 mcg/kg, followed by a continuous infusion of 0.5 mcg/kg per hour until the end of surgery. Patient in this latter group received dexmedetomidine plus sufentanil for patient-controlled intravenous analgesia postoperatively for 2 days. Both groups had 25 mg of dolasetron added to the patient-controlled intravenous analgesia solution and all mothers breastfed their infants. Both groups had good neonatal behavioral neurological assessments on days 1 and 2 postpartum.[1]
◉ Effects on Lactation and Breastmilk
A double-blind study randomized 160 women receiving an elective cesarean section under spinal anesthesia to receive either sufentanil for patient-controlled intravenous analgesia (standard care) or standard care plus dexmedetomidine. Dexmedetomidine was given as 5 mcg/kg, followed by a continuous infusion of 0.5 mcg/kg per hour until the end of surgery. Patient in this latter group received dexmedetomidine plus sufentanil for patient-controlled intravenous analgesia postoperatively for 2 days. Both groups had 25 mg of dolasetron added to the patient-controlled intravenous analgesia solution. Patients who received dexmedetomidine had a shorter time to the first lactation (28 vs 34 hours), achieved exclusive breastfeeding sooner (8 vs 11 days) and had a greater amount of milk on the second day postpartum.[1]

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Interactions
Concurrent use of cimetidine, which is a nonselective cytochrome P450 enzyme inhibitor, with dolasetron for 7 days has been found to result in a 24% increase in hydrodolasetron blood concentrations.
Concurrent use of intravenous dolasetron and atenolol has been found to result in a 27% decrease in clearance hydrodolasetron.

[1]. Outcomes Associated with 5-HT3-RA Therapy Selection in Patients with Chemotherapy-Induced Nausea and Vomiting: A Retrospective Claims Analysis. Am Health Drug Benefits. 2014 Jan;7(1):50-8.

[2]. Pooled analysis of phase III clinical studies of palonosetron versus ondansetron, dolasetron, and granisetron in the prevention of chemotherapy-induced nausea and vomiting (CINV). Support Care Cancer. 2014 Feb;22(2):469-77.

LSM-5418 is an indolyl carboxylic acid.
Dolasetron is a Serotonin-3 Receptor Antagonist. The mechanism of action of dolasetron is as a Serotonin 3 Receptor Antagonist.
See also: Dolasetron (annotation moved to).

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Mechanism of Action
Dolasetron, and its active metabolite hydrodolasetron, are highly specific and selective antagonist of serotonin subtype 3 (5-HT3) receptors. 5-HT3 receptors are present peripherally on vagal nerve terminals and centrally in the area postrema of the brain. Chemotherapeutic medications appear to precipitate release of serotonin from the enterochromaffin cells of the small intestine, which activates 5-HT3 receptors on vagal efferents to initiate the vomiting reflex. Dolasetron has not been shown to have activity at other known serotonin receptors, and has low affinity for dopamine receptors.
Dolasetron causes dose-related acute, and usually reversible, electrocardiogram (ECG) changes including QRS widening and PR, QTc, and JT prolongation; QTc prolongation is caused primarily by QRS widening. Dolasetron seems to prolong both depolarization and,to a lesser extent, repolarization time, and its active metabolites may block sodium channels.
The active metabolite of dolasetron (i.e., hydrodolasetron) may block sodium channels and prolong cardiac depolarization and, to a lesser extent, repolarization time.

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Therapeutic Uses
Antiemetic
Dolasetron injection is indicated for the prevention of nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy, including high-dose cisplatin. Dolasetron tablets are indicated for the prevention of nausea and vomiting associated with moderate-emetogenic cancer chemotherapy, including initial and repeat courses. /Included in US product label/
Dolasetron injection and tablets are indicated for the prevention of postoperative nausea and/or vomiting. Routine prophylaxis is not recommended when there is little risk of nausea and/or vomiting developing postoperatively, except in patients in whom nausea and/or vomiting must be avoided. /Included in US product label/
Dolasetron injection is indicated for the treatment of postoperative nausea and/or vomiting. /Included in US product label/

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Drug Warnings
/Administration is contraindicated in patients with/ known hypersensitivity to dolasetron mesylate.
Acute, usually reversible ECG alterations and/or risk of altered cardiac conduction. Prolongation of PR, QTC, and JT intervals and widening of the QRS complex have been observed in patients receiving dolasetron therapy. These alterations, which are caused by prolongation of cardiac depolarization and repolarization, appear to be related to plasma concentrations of the active metabolite hydrodolasetron and generally are self-limiting as these concentrations decline. ECG interval prolongation rarely has resulted in heart block or cardiac arrhythmias. Sudden death has occurred in at least one patient 6 hours after receiving IV dolasetron (1.8 mg/kg), although the patient had other potential risk factors such as prior therapy with doxorubicin and concomitant cyclophosphamide.
Dolasetron should be used with caution in patients who have or may develop prolongation of cardiac conduction intervals, particularly QTC, including those with congenital QT syndrome, those with uncorrected hypokalemia or hypomagnesemia, patients receiving diuretics that may induce electrolyte abnormalities, patients receiving antiarrhythmic agents or other drugs that alter cardiac conduction (e.g., prolong QT interval), and those receiving cumulative high-dose anthracycline therapy.
Sensitivity reactions, including anaphylactic reaction, facial edema, and urticaria, have been reported rarely. Cross-sensitivity reactions have been reported in patients receiving other selective 5-HT3 receptor antagonists but have not been reported to date with dolasetron.
For more Drug Warnings (Complete) data for DOLASETRON (7 total), please visit the HSDB record page.

C19H20N2O3

324.3737

324.147

C, 70.35; H, 6.21; N, 8.64; O, 14.80

115956-12-2

Dolasetron Mesylate hydrate; 878143-33-0; Dolasetron Mesylate; 115956-13-3; Dolasetron-d4

3033818

White to off-white solid powder

1.37 g/cm3

535.1ºC at 760 mmHg

278 ºC

277.4ºC

4.08E-10mmHg at 25°C

1.76

2.456

1

4

3

24

535

2

O(C(C1=C([H])N([H])C2=C([H])C([H])=C([H])C([H])=C12)=O)C1([H])C([H])([H])[C@]2([H])C([H])([H])C3([H])C(C([H])([H])N2C([H])(C1([H])[H])C3([H])[H])=O

UKTAZPQNNNJVKR-AKJUYKBHSA-N

InChI=1S/C19H20N2O3/c22-18-10-21-12-5-11(18)6-13(21)8-14(7-12)24-19(23)16-9-20-17-4-2-1-3-15(16)17/h1-4,9,11-14,20H,5-8,10H2/t11?,12-,13+,14?

[(3S,7R)-10-oxo-8-azatricyclo[5.3.1.03,8]undecan-5-yl] 1H-indole-3-carboxylate

Dolasetronum; HSDB 7565; HSDB-7565; HSDB7565; Dolasetron

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: ~64 mg/mL (~197.3 mM)

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.

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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).

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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)

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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).

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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

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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.

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