LECTURE 6

Salts of carboxylic acids and saturated aminoacids aliphatic series as drugs

Associate prof. Mosula L. M.

The plan

1. Salts of carboxylic acids as drugs: potassium acetate, calcium lactate, sodium hydroxybutyrate, sodium citrate, calcium gluconate.

2. The saturated aminoacids of aliphattic series: glutamic acid, cysteine hydrochloride, acetylcysteine, methionine, aminalonum.

Salts of carboxylic acids as drugsPotassium acetateCH3COOKDescription. Potassium acetate is a white crystalline powder; it is a slightly hydroscopic with characteristic odor of acetic acid and salty test.Solubility. It is soluble in water and alcohol.

Identification. A. Yields the reaction characteristic of potassium salts:

B. Yields the reactions characteristic of carboxylic acids: reacts with ethyl alcohol to form ether:

C. Acetate-ion reacts with iron (III) chloride solution to form a red complex:

Assay. Carry out a water-free titration. Dissolve the exact amount of potassium acetate in ice acetic acid and titrate with 0.2N hydrochloric acid use a crystalline-violet as an indicator.

Potassium acetate is indicated for the treatment and prevention of potassium deficiency. It also finds usefulness as a diuretic substance.

Sodium -oxibutyrateHOCH2CH2CH2COONaIt occurs as white or slightly yellow crystalline powder with characteristic odor.Identification. A. Yields a reaction characteristic of sodium salts.B. Sodium oxibutyrate reacts with hydrochloric acid to form -butyrolactone. Extract synthesized -butyrolactone with ether and identify by refractive index (1.4280-1.4360).

Assay. Cary out a water-free titration as for assay of potassium acetate.

Sodium citrate (Sodium hydrocitrate for injection)It is a white crystalline powder or colorless crystals, odorless with salty test. Identification. A. Yields the reaction characteristic of sodium salts:

B. Sodium citrate reacts with calcium chloride to form calcium salt that is insoluble in boiling water:

Calcium citrate that is obtained is soluble in hydrochloric acid.

Assay. Carry out a neutralization titration after ion exchange chromatography.

Titrate obtained citrate acid with 0.05M potassium or sodium hydroxide.4% solution of calcium citrate is used for protection of blood coagulation.

Calcium gluconateObtainingThe gluconic acid used in the preparation of calcium gluconate can be prepared by electrolytic oxidation of glucose as follows:

Gluconic acid is produced on a commercial scale by the action of a number of fungi bacteria, and molds upon 25% to 40% solutions of glucose. The fermentation is best carried out in the presence of calcium carbonate and oxygen to give almost quantitative yields of gluconic acid. The fermentation is complete in 8 to 18 days.

Prorerties.Calcium gluconate occurs as a white crystalline or granular powder, without odor or test. Its solutions are neutral to litmus paper. Solubility . One gram of calcium gluconate dissolves slowly in about 30 ml of water and in 5 ml of boiling water. It is insoluble in alcohol and in many organic solvents. The mineral acids that are stronger than gluconic acid will decompose calcium gluconate. It is incompatible with soluble sulphates, carbonates, bicarbonates, citrates, tartrates, salicylates and benzoates.Identification. A. Calcium gluconate solution yields the reaction characteristic for calcium salts.B. Solution reacts with iron chloride in neutral medium to form green complex.

Assay. Dissolve 0.4 g in 20 ml of water. Cool and add 10 ml of ammonium buffer solution, and 0.1 g of chromium-blue as an indicator, and titrate with 0.05M EDTA antill blue-violet color is obtained.

Each ml of 0.05M EDTA is equivalence to 0.02242 g of calcium gluconate.

Calcium gluconate fills the need for a soluble nontoxic well-tolerated form of calcium that can be employed orally, intramuscularly, or intravenously. Calcium therapy is indicated in conditions such as parathyroid deficiency (tetany), general calcium deficiency, and when calcium is the limiting factor in increased clotting time of the blood. It can be used both orally and intravenously.

Amino Acids as drugsProteins are essential components of all living matter. As cellular components, proteins perform numerous functions. The chemical reactions fundamental to the life of the cell are catalyzed by proteins called enzymes. Other proteins are structural constituents of protoplasm and cell membranes. Some hormones are characterized as proteins or proteinlike compounds because of their polypeptide structural features.Proteins are biosynthesized from -amino acids, and when proteins are hydrolyzed, amino acids are obtained. Some very complex (conjugated) proteins yield other hydrolysis products in addition to amino acids. -Amino acids are commonly characterized with the generalized structure:

The relative high melting point, solubility, behavior, and acid-base properties characteristic of amino acids can be accounted for on the basis of the dipolar ion structure (commonly called zwitterion). Amino acids in the dry solid state are dipolar ions (inner salts). Amino acids when dissolved in water can exist as dipolar ions.

Glutamic acid(Ph Eur monograph 0750) C5H9NO4 147.156-86-0 Action and use Amino acid. Ph Eur DEFINITION Glutamic acid contains not less than 98.5 per cent and not more than the equivalent of 100.5 per cent of (2S)-2-aminopentanedioic acid, calculated with reference to the dried substance. CHARACTERS A white, crystalline powder or colourless crystals, freely soluble in boiling water, slightly soluble in cold water, practically insoluble in acetic acid, in acetone and in alcohol.

IDENTIFICATION First identificationA, B. Second identificationA, C, D. A. It complies with the test for specific optical rotation (see Tests). B. Examine by infrared absorption spectrophotometry (2.2.24), comparing with the spectrum obtained with glutamic acid CRS. Examine the substances prepared as discs. If the spectra obtained show differences, dissolve the substance to be examined and the reference substance separately in the minimum quantity of water R, evaporate to dryness at 60 C and record new spectra using the residues.

C. Examine the chromatograms obtained in the test for ninhydrin-positive substances. The principal spot in the chromatogram obtained with test solution (b) is similar in position, colour and size to the principal spot in the chromatogram obtained with reference solution (a). D. To 2.0 ml of solution S (see Tests) add 0.1 ml of phenolphthalein solution R and 3.0 ml to 3.5 ml of 1 M sodium hydroxide to change the colour of the indicator to red. Add a mixture of 3 ml of formaldehyde solution R, 3 ml of carbon dioxide-free water R and 0.1 ml of phenolphthalein solution R, to which sufficient 1 M sodium hydroxide has been added to produce a pink colour. The solution is decolourised. Add 1 M sodium hydroxide until a red colour is produced. The total volume of 1 M sodium hydroxide used is 4.0 ml to 4.7 ml.

TESTS Solution S Dissolve 5.00 g in 1 M hydrochloric acid with gentle heating, and dilute to 50.0 ml with the same acid. Appearance of solution Solution S is clear (2.2.1) and colourless (Method II, 2.2.2). Specific optical rotation (2.2.7) + 30.5 to + 32.5, determined on solution S and calculated with reference to the dried substance. Ninhydrin-positive substances Examine by thin-layer chromatography (2.2.27), using a TLC silica gel plate R.

Chlorides (2.4.4) Dissolve 0.25 g in 3 ml of dilute nitric acid R and dilute to 15 ml with water R. The solution, to which 1 ml of water R is added instead of dilute nitric acid R, complies with the limit test for chlorides (200 ppm). Sulphates (2.4.13) Dilute 5 ml of solution S to 15 ml with distilled water R. The solution complies with the limit test for sulphates (300 ppm). Ammonium (2.4.1) 50 mg complies with limit test B for ammonium (200 ppm). Prepare the standard using 0.1 ml of ammonium standard solution (100 ppm NH4) R. Iron (2.4.9) In a separating funnel, dissolve 1.0 g in 10 ml of dilute hydrochloric acid R. Shake with 3 quantities, each of 10 ml, of methyl isobutyl ketone R1, shaking for 3 min each time. To the combined organic layers add 10 ml of water R and shake for 3 min. The aqueous layer complies with the limit test for iron (10 ppm). Heavy metals (2.4.8) 2.0 g complies with limit test D for heavy metals (10 ppm). Prepare the standard using 2 ml of lead standard solution (10 ppm Pb) R. Loss on drying (2.2.32) Not more than 0.5 per cent, determined on 1.000 g by drying in an oven at 100-105 C. Sulphated ash (2.4.14) Not more than 0.1 per cent, determined on 1.0 g.

ASSAY Dissolve 0.130 g in 50 ml of carbon dioxide-free water R with gentle heating. Cool. Using 0.1 ml of bromothymol blue solution R1 as indicator, titrate with 0.1 M sodium hydroxide until the colour changes from yellow to blue. 1 ml of 0.1 M sodium hydroxide is equivalent to 14.71 mg of C5H9NO4. STORAGE Protected from light. Ph Eur

Glutamic acid hydrochloride (Acidulin)It is essentially a pure compound that occurs as a white crystalline powder soluble 1:3 in water and insoluble in alcohol. It has been used in place of glycine in the treatment of muscular dystrophies, with rather unpromising results. It also is combined with anticonvulsants for the petit small attacks of epilepsy, a use that appears to depend on change in pH of the urine.Identification. A. As all amino acids glutamic acid reacts with ningidrin:

B. Amino acids react with copper salts to form blue-violet complexes:

C. Glutamic acid reacts with resorcin in presence of H2SO4k.

Assay Alkalimetry, direct titration. (neutralization titration) (using NaOH as titrant; bromthymole blue as indicator).

m(C5H9NO4) = .m.

Acetylcysteine (Mucomyst)Is the N-acetyl derivative of L-cysteine. It is used primarily to reduce the viscosity of the abnormally viscid pulmonary secretions in patients with cystic fibrosis of the pancreas or various tracheobronchial and bronchopulmonary diseases.Acetylcysteine is more active than cysteine. Acetylcysteine is most effective in 10% to 20% solutions. It is used by direct instillation or by aerosol nebulization. It is available as a 20% solution of the sodium salt in 10- and 30ml containers. An opened vial of acetylcysteine must be covered, stored in a refrigerator, and used within 48 houts.

Methionine (Amurex)MethioninumETHIONINE M. m. = 149,2 g/mol5H11NO2S The chemical name:-amino - - acid; 2-2-4 () acid.DL-2-amino-4-(methylthio)-butyric acid (CH3SCH2CH2CH(NH2)COOH) occurs as white crystalline platelets or powder with a slight, characteristic odor; it is soluble in water (1:30), and a 1% solution has a pH of 5.6 to 6.1. It is insoluble in alcohol. In therapy, methionine has been employed in the treatment of liver injuries caused by poisons such as carbon tetrachloride, chloroform, arsenic and trinitrotoluene. Methionin also has a function in the syntethis of choline, cystine, lecytin and probably creatine. Deficiency not only limits growth in rats, but also inhibits progression of tumors.

AminalonumAcidum gamma-aminobutyricum Gamma bosoms H2N-CH2CH2CH2COOHGammalonum M. m. = 103,12 g/mol

C4H9NO2The chemical name: 4-aminobutyric acid, -aminobytyric acid.

ObtainingAlkaline hydrolysis pirolidone-2 with the subsequent neutralisation of salt of -aminobytyric acid by means of acetic acid 3.

Properties Description. A white crystal powder with specific smell of amino acids. Hygroscopic. Solubility. Freely soluble in water, very slightly soluble in alcohol, it is practically insoluble in chloroform, acetone. a water solution 6,5 7,5.

Identification1. Ninhydrin reaction; there is a blue-violet colouring.2. Reaction with alkaline solution CuSO4; it is formed chelate compound of intensively dark blue colour.3. Fusion with KSCN; allocation of hydrogen sulphide H2S which revealing by means of lead-acetic paper: S2 - + Pb2 + PbS black4. Heating with alloxan (mesoxalyl urea) in the medium of dimethylformamide; there is a bright-crimson colouring.

Assay1. Acidimetry, non-aqueous titration. itrant perchlorate acid HClO4, medium anhydrous acetic acid 3, the indicator crystal violet (from violet before blue-green colouring).HOOC(CH2)3NH2 + HClO4 HOOC(CH2)3NH3+ClO4In parallel spend control experience.m (C4H9NO2) = M. m.

2. Alkalimetry, direct titration of an investigated solution of a substance by a standard solution NaOH in the presence of the solution indicator bromthymol dark blue before transition of yellow colouring in the blue-green.H2N - (CH2)3COOH + NaOH = H2N - (CH2)3COONa + H2Om (C4H9NO2) = M. m.StorageIn densely corked containers, in the dry cool place protected from light.Application. NeuromediatorThe release form: tablets on 0,25 g.

Aminocaproic acid (Amicar)6-Aminohexanoic acid occurs as fine, white crystalline powder that is freealy soluble in water, slightly soluble in alcohol, and practically insoluble in chloroform.Aminocaproic acid has been used in the control of hemorrhage in certain surgical procedures. It is of no value in controlling hemorrhage caused by thrombocytopenia or other coagulation defects or vascular disruption. Aminocaproic acid is well absorbed orally. Plasma peaks occur in about two hours. It is rapidly, largely unchanged.

CYSTEINE Cysteinum M. m. = 121,2 g/molC3H7NO2SCysteine contains not less than 98,0 % and no more than 101,0 % (R)-2-amino-3-mercaptopropanoic acid, in recalculation on a solid.The chemical name: (R)-2-amino-3-mercaptopropanoic acid.Properties Description. A crystal powder of white colour or colourless crystals with a characteristic smell.Solubility. Freely soluble in water R and 96 % alcohol R, it is practically insoluble in ether R.

IdentificationThe first identification: A, B.The second identification: A, B, C, D.A. Measuring of specific optical rotation by means method of polarimetry. From + 8,0to to + 9,5 in recalculation on a solid. Definition make, using a substance solution in a solution 220 g/l chloride acid R.B. IR-spectroscopy.C. Reaction with ninhydrin.Technique. About 10 mg of a substance dissolve in 2 ml of water R, add 0,1 M solution HCl to nearby 4,0, 0,5 ml of a solution 2,5 g/l ninhydrin R, heat up on a water heater during 10 mines; there is a yellow or yellowy-brown colouring. The received solution cool to a room temperature, add drops from 1 ml to 2 ml of 0,1 M solution NAOH; there is a red-violet colouring.

D. Identification mercapto-group with the help sodium nitroprusside after heating with alkali solution.Technique. About 5 mg of a substance dissolve in 5 ml water R, add 2 ml solution NaOH diluted R and 0,2 ml 25 g/l solution sodium nitroprusside Na2 [Fe (CN) 5NO], ; there is a yellow colouring which during 2 mines passes in the red.2HSCH2CH2CH(NH2)COOH + 4NaOH Na2S + 2NH3 + 2HOCH2CH2CH(OH)COONaNa2S + Na2[Fe(CN)5NO] Na4[Fe(CN)5NOS]E. Reaction with H2O2 and solution FeCl3 and the next revealing SO42- by means of reagent barium of chloride R1 in the medium of chloride acid diluted R.SO42 - + Ba2 + BaSO4white precipitate or opalescenseReaction with salts of Copper (); the black precipitate is formed.

Tests1. solution. From 4,5 to 6,0. 2. Specific optical rotation. From +8,0 to +9,5, in recalculation on a solid. Measure optical rotation of solution substance in 220g/l solution chloride acid.3. The general impurity of chlorides, sulphates, ammonium of salts, Iron, heavy metals within corresponding standards.4. Weight loss at drying. At drying 1,000 g substance at temperature from 100 C to 105 C weight loss should be no more than 0,5 %.9. Sulphatic ashes. No more than 0,1 %. Definition spend with 1,0 g substance.10. Pyrogens or bacterial endotoxins.

ASSAY 1. SPU. Iodometry, back titration. Shot of substance dissolve in l diluted R, cool in an ice cooler, add crystal and excess of a standard solution 2. After keeping of a solution during 15 mines in the place protected from light not reacted 2 titrate by standard solution Na2S2O3, using in the end of titration the indicator starch (before disappearance of dark blue colouring).cysteine T homocystinI2 + 2Na2S2O3 = 2NaI + Na2S4O6 not reactedIn parallel spend control experience.m (C3H7NO2S) = M. m.

2. Iodometry, direct titration. Shot of substance dissolve in solution HCl, add KI and titrate by standard solution I2 in the presence of starch before occurrence of dark blue colouring.

StorageIn densely corked containers, in banks from dark glass, in the place protected from light.Application. For treatment of initial forms of a cataract.Apply 5 % water solution at initial forms of a cataract. Is a part of eye drops.

Thanks for attention!