Absorption, Distribution and Excretion
In a study, three patients were administered 50 mg of radiolabelled 14C-benserazide by both intravenous and oral routes. Three additional patients received oral doses of 50 mg 14C-benserazide alone. Comparison of the time-plasma concentration curves of total radioactivity in the patients receiving oral and intravenous 14C-benserazide indicated that between 66% and 74% of the administered dose was absorbed from the gastrointestinal tract. Peak plasma concentrations of radioactivity were detected one hour after oral administration in five of the six patients.
Benserazide is rapidly excreted in the urine in the form of metabolites, mostly within the first 6 hours of administration, 85% of urinary excretion occurs within 12 hours. Elimination of radiolabelled 14C-benserazide was primarily by urinary excretion with 86% to 90% of an intravenous dose recovered in the urine while 53% to 64% of an oral dose was detected in the urine. The majority of the 14C-benserazide was ultimately accounted for in the urine within 48 hours after administration. Fecal recovery studies conducted over five to eight days accounted for the majority (about 30%) of the remainder of the administered 14C-benserazide. Ultimately, benserazide is almost entirely eliminated by metabolism. These metabolites are mainly excreted in the urine (64%) and to a smaller extent in the feces (24%).
Readily accessible data regarding the volume of distribution of benserazide is not available.
Readily accessible data regarding the clearance of benserazide is not available.

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Metabolism / Metabolites
Benserazide is hydroxylated to trihydroxybenzylhydrazine in the intestinal mucosa and the liver. Trihydroxybenzylhydrazine is a potent inhibitor of the aromatic acid decarboxylase, and it is believed that the levodopa in a levodopa/benserazide combination product is largely protected against decarboxylation mainly by way of this benserazide metabolite.

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Biological Half-Life
The half-life of benserazide is documented as 1.5 hours.

Protein Binding
Benserazide is observed as experiencing 0% protein binding.

[1]. Benserazide is a novel inhibitor targeting PKM2 for melanoma treatment. Int J Cancer. 2020 Jul 1;147(1):139-151.

Benserazide is a carbohydrazide that results from the formal condensation of the carboxy group of DL-serine with the primary amino group of 4-(hydrazinylmethyl)benzene-1,2,3-triol. An aromatic-L-amino-acid decarboxylase inhibitor (DOPA decarboxylase inhibitor) that does not enter the central nervous system, it is used as its hydrochloride salt as an adjunct to levodopa in the treatment of parkinsonism. By preventing the conversion of levodopa to dopamine in the periphery, it causes an increase in the amount of levodopa reaching the central nervous system and so reduces the required dose. Benserazide has no antiparkinson actions when given alone. It has a role as an EC 4.1.1.28 (aromatic-L-amino-acid decarboxylase) inhibitor, an antiparkinson drug and a dopaminergic agent. It is a carbohydrazide, a member of catechols, a primary amino compound and a primary alcohol. It is a conjugate base of a benserazide(1+).
When levodopa is used by itself as a therapy for treating Parkinson's disease, its ubiquitous metabolism into dopamine is responsible for a resultant increase in the levels of circulating dopamine in the blood and to various extracerebral tissues. This can result in a number of side effects like nausea, vomiting, or even cardiac arrhythmias that may diminish patient adherence. A decarboxylase inhibitor like benserazide is consequently an effective compound to combine with levadopa as it is incapable of crossing the blood-brain barrier itself but acts to prevent the formation of dopamine from levadopa in extracerebral tissues - thereby acting to minimize the occurrence of extracerebral side effects. Levodopa/benserazide combination products are used commonly worldwide for the management of Parkinson's disease. In particular, although the specific levodopa/benserazide combination is formally approved for use in Canada and much of Europe, the FDA has approved another similar levodopa/dopa decarboxylase inhibitor combination in the form of levodopa and carbidopa. Moreover, the European Medcines Agency has conferred an orphan designation upon benseraside since 2015 for its potential to be used as a therapy for beta thalassaemia as well.
An inhibitor of DOPA DECARBOXYLASE that does not enter the central nervous system. It is often given with LEVODOPA in the treatment of parkinsonism to prevent the conversion of levodopa to dopamine in the periphery, thereby increasing the amount that reaches the central nervous system and reducing the required dose. It has no antiparkinson actions when given alone.

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Drug Indication
The primary therapeutic use for which benserazide is currently indicated for is as a combination therapy with levadopa for the treatment of Parkinson's disease in adults > 25 years of age, with the exception of drug-induced parkinsonism. At certain doses, the combination product of levodopa and benserazide may also be used to treat restless legs syndrome, which is sometimes associated with Parkinson's disease. There have also been some studies that have prompted the European Medicines Agency to confer orphan designation upon benserazide hydrochloride as a potential therapy for beta thalassaemia. Although studies are ongoing, no evidence has been formally elucidated as of yet.

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Mechanism of Action
The combination of levodopa and benserazide is an anti-Parkinsonian agent. Levodopa itself is the metabolic precursor of dopamine. In Parkinson's disease, dopamine is depleted to a large degree in the striatum, pallidum, and substantia nigra in the central nervous system (CNS). The administration of levodopa to treat the disease is subsequently proposed to facilitate raises in the levels of available dopamine in these areas. The metabolism of levodopa to dopamine occurs via the enzyme dopa decarboxylase, although unfortunately, this metabolism can also occur in extracerebral tissues. As a result, the full therapeutic effect of an administered dose of levodopa may not be obtained if portions of it are catabolized outside of the CNS and various patient adherence diminishing extracerebral side effects due to the extracerebral presence of dopamine like nausea, vomiting, or even cardiac arrhythmias can also happen. Subsequently, a peripheral decarboxylase inhibitor like benserazide, which blocks the extracerebral decarboxylation of levodopa, when administered in combination with levodopa has obvious and significant advantages. Such benefits include reduced gastrointestinal side effects, a more rapid and complete response at the initiation of therapy, and a simpler dosing regimen. It is important to note, however, that benserazide is hydroxylated to trihydroxybenzylhydrazine in the intestinal mucosa and the liver, and that as a potent inhibitor of the aromatic amino acid decarboxylase, it is this trihydroxybenzylhydrazine metabolite of benserazide that mainly protects levodopa against decarboxylation to dopamine in the gut and also around the rest of the body outside of the blood-brain barrier. Regardless, because Parkinson's disease progresses even with the therapy of levodopa and benserazide, this kind of combined therapy is only ever indicated if it is capable of improving the quality of life and adverse effect profile of using such drugs for Parkinson's patients and there is little to be gained by switching to or starting this combination therapy if patients are already being managed with stable, effective, and well-tolerated levadopa-only therapy. Finally, it is also proposed that benserazide hydrochloride may be able to treat beta thalassaemia by maintaining the active expression of the gene for fetal hemoglobin so that constant production of fetal hemoglobin may replace the missing adult hemoglobin variation that is characteristic of patients with the condition, thereby decreasing the need for blood transfusion therapy.

C10H15N3O5

257.2432

257.101

322-35-0

Benserazide hydrochloride;14919-77-8

2327

Typically exists as solid at room temperature

1.541 g/cm3

574.2ºC at 760 mmHg

301ºC

1.678

-1.3

7

7

5

18

278

0

[2H]C(C([2H])(O)[2H])(N)C(NNCC1=C(O)C(O)=C(O)C=C1)=O.Cl

BNQDCRGUHNALGH-UHFFFAOYSA-N

InChI=1S/C10H15N3O5/c11-6(4-14)10(18)13-12-3-5-1-2-7(15)9(17)8(5)16/h1-2,6,12,14-17H,3-4,11H2,(H,13,18)

2-amino-3-hydroxy-N'-[(2,3,4-trihydroxyphenyl)methyl]propanehydrazide

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

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.)