What Is Carbidopa?

Carbidopa (Pinyin: Kabiduoba, English name: Carbidopa-130) This product is (S) --methyl--hydrazino-3,4-dihydroxyphenylpropionic acid monohydrate. Calculated as anhydrate , Containing C10H14N2O4 should not be less than 99.0%. This product is white-like villous crystal; almost odorless. Used in combination with levodopa for Parkinson's disease and Parkinson's syndrome.

Chinese name: Carbidopa
Foreign name: Carbidopa

Category: Decarboxylase inhibitor
Storage and shelf life: Shading, sealed

Carbidopa Basic Information

[Overview]

[English / Latin name] Carbidopa

Carbidopa molecular formula

[Storage and shelf life] shading and sealed.

[Preparation / specification] Carbidopa tablets

[Category] Decarboxylase inhibitors.

[Identification] The infrared light absorption spectrum of the product should be consistent with the control spectrum (spectral set 97).

CAS NO. 38821-49-7

[Chinese alias] (S) -alpha-methyl-alpha-hydrazino-3,4-dihydroxyphenylpropionic acid monohydrate

[English alias] (+)-2- (3,4-Dihydroxybenzyl) -2-hydrazinopropionic acid monohydrate

[Molecular formula] C10H14N2O4H2O

[Molecular weight] 244.25

Carbidopa pharmacological application

Carbidopa has a strong peripheral dopa decarboxylase inhibitor. Difficult to penetrate the blood-brain barrier, when combined with levodopa, only inhibits the activity of peripheral dopa decarboxylase, reduces the production of dopamine in peripheral tissues, alleviates its peripheral adverse reactions, and then increases the amount of levodopa entering the center and improves the brain The concentration of endodamine enhances the efficacy of levodopa, so it is an important auxiliary drug for levodopa. Carbidopa is not effective on its own. Clinically, carbidopa and levodopa are usually mixed at a ratio of 1:10 or 1: 4 to make compound preparations.

Carbidopa Drug Traits

This product is almost white fluffy crystal; almost odorless. The product is slightly soluble in water or methanol, almost insoluble in ethanol or chloroform; easily soluble in dilute hydrochloric acid. Take this product with specific rotation, weigh it accurately, add aluminum trichloride solution (take 40g of aluminum trichloride, add water to dissolve and dilute to 60ml, shake well, if color develops, add 0.5g of activated carbon, stir for 10 minutes, filter Use a 10% sodium hydroxide solution to adjust the pH to 1.5, that is, an appropriate amount. Shake it in a hot water bath to dissolve it, remove it, let it cool, and add aluminum trichloride solution to make a solution containing 10mg per 1ml. Determined according to law (Appendix VI E), the specific rotation should be -20.0 ° to -23.5 °. The absorption coefficient is taken from this product, accurately weighed, dissolved in 0.1mol / L hydrochloric acid solution and quantitatively diluted to a solution containing about 50 g per 1 ml, and the absorption is measured at a wavelength of 281 ± 2 nm according to spectrophotometry (Appendix IV A). Degree, absorption coefficient (E1% 1cm) is 117 to 129.

Carbidopa drug check

Take this product, add 1% methanolic hydrochloric acid solution to make a solution containing 10mg per 1ml as a test solution; take an appropriate amount, add 1% methanolic hydrochloric acid solution and dilute to 50g, 100g and 150 g of the solution was used as control solutions (i), (ii) and (iii). According to the thin layer chromatography (Appendix V B) test, 10 l of each of the above four solutions was pipetted and spotted on the same silica gel G thin layer plate with n-butanol-toluene-butanone-pyridine-glacial acetic acid-water (1: 3: 3: 1: 1.5: 0.8) as a developing agent. After unfolding, dry it, and place it in iodine vapor for 15 minutes, then inspect it immediately. The test solution showed no more than two spots of impurities, and their colors were compared with the main spots of control solutions , , and , respectively. The total amount of impurities must not exceed 2.0%. Take this product for moisture and measure it according to the moisture measurement method (Appendix M, first method A). The moisture content should be 6.9% to 7.9%. Take 1.0 g of the residue from the burning residue and inspect it according to law (Appendix N). The residual residue shall not exceed 0.1%. The heavy metal shall be taken as the residue left under the burning residue, and shall be inspected in accordance with the law (Appendix H second method). The content of heavy metal shall not exceed 10 parts per million.

Carbidopa determination

Take about 0.25g of this product, weigh it accurately, add 15ml of perchloric acid solution (0.1mol / L) precisely, dissolve, add 15ml of acetic anhydride and 2 drops of crystal violet indicator solution, and use sodium acetate titration solution (0.1mol / L) Titrate until the solution appears green, and correct the result of the titration with a blank test. Each 1ml of perchloric acid titration solution (0.1mol / L) is equivalent to 22.62mg of C10H14N2O4.

Carbidopa

Method name: Carbidopa API-Determination of Carbidopa-Non-aqueous titration

Scope of application: This method uses a titration method to determine the content of carbidopa in the carbidopa drug substance.

This method is suitable for carbidopa drug substances.

Principle of the method: After the test product is dissolved with perchloric acid titration solution, add acetic anhydride and crystal violet indicator solution, titrate with sodium acetate titration solution until the solution is green, and correct the titration result with a blank test, according to the amount of titrant used Calculate the content of carbidopa.

Reagent: 1. Glacial acetic acid

Acetic anhydride

Perchloric acid titrant (0.1mol / L)

Sodium acetate titration solution (0.1mol / L)

Anhydrous sodium carbonate

Crystal violet indicator liquid

Reference potassium hydrogen phthalate

equipment:

Sample preparation: 1. Perchloric acid titration solution (0.1mol / L)

Preparation: Take 750mL of anhydrous glacial acetic acid (calculated with water content, add 5.22mL of acetic anhydride per 1g of water), add 8.5mL of perchloric acid (70 ~ 72%), shake well, let cool, add an appropriate amount of anhydrous glacial acetic acid 1000mL, shake well and leave for 24 hours. If the test sample is easily acetylated, the water content of the solution must be determined by the moisture measurement method, and then the water content of the solution is adjusted to 0.01% ~ 0.2% with water and acetic anhydride.

Calibration: Take about 0.16g of standard potassium hydrogen phthalate dried to constant weight at 105 , accurately weigh, add 20mL of anhydrous glacial acetic acid to dissolve, add 1 drop of crystal violet indicator solution, and slowly titrate with this solution to Blue, and the titration results are corrected with a blank test. Each 1mL of perchloric acid titration solution (0.1mol / L) is equivalent to 20.42mg of potassium hydrogen phthalate. Calculate the concentration of this solution based on the consumption of this solution and the amount of potassium hydrogen phthalate taken.

Sodium acetate titration solution (0.1mol / L)

Preparation: Take 5.3g of anhydrous sodium carbonate, add 100mL of anhydrous glacial acetic acid (calculated with water content, 5.22mL of acetic anhydride per 1g of water), add anhydrous acetic acid to 1000mL, and shake well.

Calibration: Precisely measure 15mL of perchloric acid titration solution (0.1mol / L), add a few drops of crystal violet indicator liquid, titrate to green with this solution, calculate the concentration of this solution based on the consumption of this solution, and get.

Crystal violet indicator liquid

Take 0.5 g of crystal violet and add 100 mL of glacial acetic acid to dissolve.

Operation steps: Weigh accurately about 0.25g of the test sample, add 15mL of perchloric acid titration solution (0.1mol / L) precisely, add 2 drops of acetic anhydride and crystal violet indicator solution, and use sodium acetate titration solution (0.1mol / L) Titrate until the solution appears green, and correct the result of the titration with a blank test. Each 1mL of perchloric acid titration solution (0.1mol / L) is equivalent to 22.62mg of C10H14N2O4.

Note: "Precision weighing" means that the weighed weight should be accurate to one thousandth of the weighed weight. "Precision measurement" means that the accuracy of measuring the volume should meet the accuracy requirements of the volume pipette in national standards.

References: Pharmacopoeia of the People's Republic of China, compiled by the National Pharmacopoeia Committee, Chemical Industry Press, 2005 edition, one, p.103.