INTRODUCTION:

Isoniazid was discovered in 1912, was introduced in therapeutics since 1951, as a result of discovery of tuberculosis antimycobacterium action has also been shown efficient against tuberculosis by inhibiting mycolic acid.

Tuberculosis is one of the most common infections caused by Mycobacterium tuberculosis. According to the World Health Organization, nearly one third of the world population is exposed to the tuberculosis pathogen

There are a number of factors that make people more susceptible to infection with tuberculosis; the most important is the human immunodeficiency virus (HIV). Also, smoking increases the risk of tuberculosis (2)

Isoniazid is an organic compound which is part of what makes the first-line drugs used in the prevention and treatment of tuberculosis (3)

This organic compound although it was discovered in 1912, was introduced in therapeutics since 1951, as a result of the discovery of tuberculosis antimycobacterium action has also been shown efficient against tuberculosis by inhibiting mycolic acid (4).

To gether isoniazid and rifampicin are the most active drugs to combat tuberculosis. Used in all forms of tuberculosis, combination with other synergists. It has very low toxicity and good tolerance. Isoniazid is never used alone to treat active tuberculosis because resistance quickly is developing (5).

Isoniazid have several other properties also which are not much renowned such as antimycobacterial, antibacterial, anti-virus, antimicrobial, antimalarial, anti-fungal, anticancer, anti- analgesic, anti-convulsant, anticorrosive and anti-inflammatory activities effect (6). Isoniazid is a prodrug and must be activated by a bacterial enzyme catalaseperoxidase, which in M. tuberculosis Kat G is called. It is bactericidal and bacteriostatic and inhibits P450.

Isoniazid inhibits also the development stages of the malaria parasites (Plasmodium gallinaceum) produced by mosquitoes. Increasing drug resistance (such as rifampicin and isoniazid antimycobacterial) against strains of M. tuberculosis leads to the necessity of finding more effective drugs for the effective management of tuberculosis (7). New hydrazone have been prepared by the reaction of isoniazid (HIN) with benzaldehyde, o-chlorobenzaldehyde and vanilla. The compounds show activity in mice that were infected with different strains of M. tuberculosis, and indicates a lower toxicity than hydrazine, isonicotinic acid.

Isoniazid can be made in several chemical methods: The potassium permanganate oxidation, air oxidation, oxidation with ozone, electrolysis method

The last few years Isoniazid is an important drug. Because it is used for treatment of tuberculosis.

MATERIALS AND METHODS:

1. Citrazinic acid from citric acid. [Step A and B]:

We found that citric acid in presence of a catalytic amount of p- toluenesulfonic acid or an alkanesulfonic acid could be esterified to the 1, 3- diester, which not be isolated. The reaction mixture after esterification was treated directly with aqueous ammonia at 120⁰c -130⁰c in a closed system and after at atmospheric pressure with caustic soda. Acidification yielded 43.7% of crude citrazinic acid based on total citric acid input (8). The crude citrazinic acid was used in next step.

2. 2, 6 – Dichloroisonicotinic acid. [ Step c]

Heating crude citrazinic acid at 125c in an ichlorin with three times its weight of phosphorus oxy – chloride gave 92.6% of crude 2, 6- dichloroisonicotinic acid (8, 11). Recrystallization from dilute alcohol gave a purified acid, suitable for next step.

3. Isonicotinic Acid. [Step D]

The ichlorination of 2, 6 – dichloroisonicotinic acid by hydrogenation was accomplished by a modification of method of wibaut using raney nickel catalyst in alkaline medium the total yield of isonicotinic acid obtained was 87.5% (11) The first product was obtained free acid, the remainder as copper salt. Both used in next step.

4. Ethyl Isonicotinate [Step E]

Direct esterification of isonicotiinic acid with ethanol and sulfuric acid gave a yield of 69.4% of ester but recovery of unesterified isonicotinic acid as its copper salt and re- esterification of latter brought the yield to 86.9% (11) A recent report describes the preparation of ester via acid chloride in 90% yield

5. Isoniazid [Step F]

Heating ethyl Isonicotinate in refluxing ethanol with a 10% excess of 85% hydrazine hydrate yielded, in two crops, 97% of Isoniazid (13).

EXPERIMENTAL WORK:

1. Citrazinic acid:

A mixture of 57.6gm of anhydrous citric acid, 1.5gm of p – toluenesulfonic acid monohydrate and 75 mi. of anhydrous methanol was heated under reflux with stirring. after about 10 min a clear solution was obtained. stirring was stopped, but heating continued for about 2 hours and thirty min. the warm reaction mixture was transferred to an autoclave, 300ml. of concentrated ammonia was added and the mixture heated at 120⁰c-130⁰c for 2 hours. after partial cooling, 35gm of sodium hydroxide was added and the solution was concentrated to 350-400ml. in the course of about five hours. After cooling and filtering the mixture was re- warmed to 80c and acidified to pH of less than 3 by the cautious addition, with stirring, of about 60ml of 50% sulfuric acid. The suspension of citrazinic acid was cooled in ice, the product removed by filtration, washed with ice water and dried at 120⁰c- 125⁰c the yield of brown product suitable for the next step was 20.4gm [43,7%]. A lighter colored product could be obtained by dissolving the crude in warm 75% sulfuric acid and pouring the solution into cold water or by recrystallizing it from concentrated hydrochloric acid (8,9). Recoveries in both cases were excellent.

2. 2, 6 – Dichloroisonicotinic acid:

An autoclave was charged with 150gm of crude citrazinic acid and 450gm 0f phosphorus oxychloride. The mixture was heated at 120⁰c internal temperature for four hours, the pressure developed was about 200 Ib. After cooling to room temperature 500ml, of ice water was added. The mixture was stirred on the steam bath for 2 hours and chilled. The dark lower oily layer solidified, was removed by filtration, washed with ice water, and dried at 125⁰c. The yield of crude dark brown product was 172gm. [92.6%]. The crude product was dissolved in 520ml. of ethanol and filtered: the filtrate was diluted with an equal volume of water and chilled. The precipitated purified product was removed by filtration, washed with cold 50% alcohol and dried at 125⁰c, A second crop was removed by concentrating the mother liquor to one – half its volume. The purified material was tan, 16.91gm. [91%] M.P. 205⁰c and was suitable for next step (9). A purer product was obtained by dissolving the recrystallized product in dilute alkali, charcoaling, filtering and reprecipitating by the addition of acid to pH 1-2. This product, recovered in 99% yield was white to pale yellow, M.P.209⁰c -210⁰c (10).

3. Isonicotinic Acid:

A solution of 20.0gm. of 2, 6-dichloroisonicotinic acid in 200ml. of water containing 29.5gm. Of sodium hydroxide was added 20.0gm (8). Of Raney nickel. The mixture was hydrogenated at 50⁰c-70⁰c and 60-85 lb. pressure until up- take of hydrogen ceased (5-7 hours). The mixture was cooled to room temperature, and filtered; the catalyst was washed twice with 10ml. portions of water which were added to the filtrate and once with alcohol which was discarded. The catalyst was stored under alcohol for further use.

The aqueous solution was acidified to pH 6.5-7 by the addition of 10% sulfuric acid, charcoaled, and filtered. The filtrate was further acidified to pH 3.5, and chilled. The precipitated isonicotinic acid (4.4-5.2gm. 34.4-40.5% white to gray) was removed by filtration, washed with ice water, and dried at 100c (10,11).

The combined mother liquor and washes were brought to pH 6.5 and warmed to 80⁰c. With stiring, 35ml. of 30% copper sulfate was added. The mixture was cooled to room temperature, and allowed to stand for several hours (12,14). The copper isonicotinate after filtration, washing and drying weighed 8.08gm. equivalent to 6.54 gm. of isonicotinic acid (51.1%). Both the crude acid and its copper salt could be used for the next step.

Recrystallization of the crude isonicotinic acid gave a white product in 90% recovery; when mother liquor was re-used the recovery was 98-99%.

4. Ethyl 1sonicotinate.

A suspension of 49.2gm. of isonicotinic acid in 183.5 ml. of absolute ethanol was stirred and cooled while 94.1 gm. of concentrated sul- furic acid was slowly added. The temperature did not rise above 25⁰c. Then the mixture was brought to reflux and kept at that temperature for four hours. After the first ten minutes the solid was in solution and stirring was unnecessary.

The mixture was cooled externally to 15⁰c, and poured on 600gm. of Ice. with stirring, about 129gm. Of sodium carbonate was added carefully to pH 8-9; the temperature during the neutralization was maintained at 5⁰c-10⁰c. The mixture was filtered and the filtrate ulas extracted with three 100ml. portions of ethylene dichloride. The organic solution was dried over anhydrous potassium carbonate and filtered. The solvent was removed at atmos- pheric pressure, the last portions at 125 mm. The product was collected at 105⁰c-106⁰c/15 mm. (92c at 12mm.) and weighed 41.8 gm. (69.4%) (9).

The alkaline aqueous liquor was acidified with sulfuric acid to pH 6.5. It was then warmed to 80⁰c and 250 ml. of 30% copper sulfate was added. The pH was readjusted and the mixture cooled to room temperature. The crude copper isonicotinate. After filtration, washing and drying weighed 25.7gm. The copper salt was treated with ethanol and sulfuric acid as above. After the esterification, the copper sulfate was removed by filtration, the filtrate poured onto ice, made ammoniacal while cold, and extracted with ethylene dichloride. Distillation yielded an additional 9.5gm. of ethyl isonicotinate. Further recovery of copper isonicotinate could be made from the new alkaline aqueous liquor.

5. 1soniazid.

A solution of 20.0gm. of ethyl isonicotinate in 50ml. of absolute ethanol was stirred while 11.0gm. Of 85% hydrazine hydrate was added rapidly. The solution was brought to and held at reflux for two hours. It was then cooled, with vigorous stirring. Seeded if necessary, and finally chilled to 10⁰c (14). The first crop of product was removed by filtration and washed with 5ml. of cold ethanol: 15.1gm. (8330%), white, m. p. 170.8⁰c-171.5⁰c. A second crop was obtained after concentrating the mother liquor and washes: 2.4gm. (14%), white, m. p. 170.0⁰c -170.8⁰c

REFERENCES:

1. Baizer MM, Dub M, Gister S, Steinberg NG. Synthesis of Isoniazid from Citric Acid. J Am Pharm Assoc (Scientific Ed) [Internet]. 1956;45(7): 478–80.

2. Counihan HE, Abrahamson ML, O’connor MH, Dickenson J. Isoniazid in pulmonary tuberculosis. J Ir Med Assoc. 1953 Jan;32(187): 18–20.

3. Isoniazid in pulmonary tuberculosis. Br Med J. 1952 Oct;2(4787): 764–5.

4. Pansy FE, Koerber WL, Stander H, Donovick R. The inactivation of isoniazid by Dubos medium. Am Rev Tuberc. 1953 Aug;68(2): 284–5.

5. van Hest R, Baars H, Kik S, van Gerven P, Trompenaars M-C, Kalisvaart N, et al. Hepatotoxicity of rifampin-pyrazinamide and isoniazid preventive therapy and tuberculosis treatment. Clin Infect Dis an Off Publ Infect Dis Soc Am. 2004 Aug;39(4): 488–96.

6. Tripathi A, Nadaf YF, Bilehal D, Nayak S, Gaonkar SL. A review on synthesis of isoniazid derivatives and their biological properties. Int J Pharm Res. 2019;11(1): 21–36.

7. Gupta A, Kaul A, Tsolaki AG, Kishore U, Bhakta S. Mycobacterium tuberculosis: immune evasion, latency and reactivation. Immunobiology. 2012 Mar;217(3): 363–74.

8. “The United States Pharmacopeia,” 15th rev., Mack Publishing Co., Easton, Pa., 1955, p. 367.

9. Mayer and Nally, Monatsh., 33,400 (1912)

10. Behrmann and Hofmann, Ber., 17, 2681(1884)

11. U. S. pat. 2,728,773, Dec 27, 1955, M. M. Baiser to the New York Quinine and Chemical Works, Inc.

12. Wibaut, J. P., Rec. trav. Chim., 63,141(1944)

13. Chem. Abstr., 47, 10531b (1953)

14. Schraeter, G. and Schmitr, Ber, 35, 2085(1902); Schroeter, G., Ber.,38, 3194(1905).

Received on 08.07.2020 Modified on 12.08.2020

Asian J. Pharm. Tech. 2021; 11(1):1-4.

DOI: 10.5958/2231-5713.2021.00001.5