Isoniazid Ethionamide

Aminosalicylic acid - Cycloserine - Ethambutol - Ethionamide - Isoniazid - Pyrazinamide Rifampin... 

The most common drugs responsible for acneform eruptions are ACTH, androgenic hormones, anticonvulsants (hydantoin derivatives, phenobarbital, trimethadione), corticosteroids, danazol, disulfiram, halogens (bromides, chlorides, iodides), lithium, oral contraceptives, tuberculostatics (ethionamide, isoniazid, rifampin), vitamins B2, B6, and B12. 

Extracted acetazolamide, ampicillin, bromazepam, caffeine, carbamazepine, chloramphenicol, chlorothiazide, diazepam, droperidol, ethionamide, isoniazid, methadone, penicillin G, phenobarbital, phenytoin, prazepam, propoxyphene, pyrazinamide, rifampin, trime-prazine, trimethoprim... 

Hepatotoxicity can occur with several antituberculous drugs including ethionamide, isoniazid, pyrazinamide and rifampicin and high alcohol consumption/chronic alcoholism has been reported to increase the risk. However, one study in patients with active tuberculosis taking rifampicin and pyrazinamide, found that of the 14 patients who developed hepatotoxicity, only 5 of these reported alcohol use (not quantified), and alcohol was not found to be associated with an increased risk of hepatotoxicity. Similarly, another study found that alcohol consumption was not a risk factor for antimycobacterial-induced hepatotoxicity. ... 

Antimycobacterials and related drugs Aminosalicylic acid (PAS), Capreomycin, Clofazimine, Cycloserine, Dapsone, Ethambutol, Ethionamide, Isoniazid, Methaniazide, Protionamide, Pyrazinamide, Rifabutin, Rifampicin (Rifampin), Rifamycin, Rihipentine, Rihiximin... 

Tear-Efrin - Phenylephrine HCI Tebacin acid - Aminosalicylic acid Tebertin - Inosine Teberus Ethionamide Tebesium - Isoniazid Tebilon - Isoniazid Tebloc - Loperamide HCI Tebrezid - Pyrazinamide Techlon - Pentoxifylline Teclinazets - Tetracycline T-E Cypionate - Estradiol cypionate Tedarol - Triamcinolone Tedarol - Triamcinolone acetonide Tedarol - Triamcinolone diacetate Teejel - Choline salicylate Tefsiel - Tegafur... 

Fig. 5.17 Antitubercular compounds (see text also for details of antibiotics) A, PAS B, isoniazid C, ethionamide D, pyrazinamide E, prothionamide F, thiaeetazone G, ethambutol.

Elevations of serum transaminase concentrations generally are not correlated with the residual capacity of the liver to metabolize drugs, so these markers cannot be used directly as guides for residual metabolic capacity. Hepatically cleared TB drugs include isoniazid, rifampin, pyrazinamide, ethionamide, and p-aminosalicylic acid.39 Ciprofloxacin is about 50% cleared by... 

Drugs of choice are isoniazid, rifampin, ethambutol, along with streptomycin and pyrazinamide. Less well tolerated, second-line agents include p-aminosal-icylic acid, cycloserine, viomycin, ka-namycin, amikacin, capreomycin, ethionamide. 

Drugs that may interact with cycloserine include alcohol, ethionamide, and isoniazid. 

Drugs that may interact with zalcitabine include antacids, chloramphenicol, cisplatin, dapsone, didanosine, disulfiram, ethionamide, glutethimide, gold, hydralazine, iodoquinol, isoniazid, metronidazole, nitrofurantoin, phenytoin, ribavirin, vincristine, cimetidine, metoclopramide, amphotericin, aminoglycosides, foscarnet, antiretroviral nucleoside analogs, pentamidine, and probenecid. 

Ethionamide is an analog of isoniazid and also inhibits mycolic acid synthesis. Its usefulness is limited by the rapid development of resistance. It can cause intense gastric pain and, like isoniazid, may also be neurotoxic. 

Ethionamide (Trecator) is a derivative of isonicotinic acid and is chemically related to isoniazid. It is a secondary agent used in combination when primary agents are ineffective or contraindicated it is a bacteriostatic antituberculosis agent. Its exact mechanism of action is unknown but is believed to involve inhibition of oxygen-dependent mycolic acid synthesis. It is thought that mutations in the region of the (tnhA) gene that are involved in mycolic acid synthesis can cause both isoniazid and ethionamide resistance. 

A. Ethambutol is associated with retrobulbar neuritis, resulting in loss of central vision and impaired red-green discrimination. Ethionamide (B) is an analogue of isonicotinic acid and is associated with GI intolerance and peripheral neuropathy, but not the optic neuritis or color vision discrimination problems. Aminosalicylic acid (C) can cause GI irritation and bleeding problems, so caution is required in peptic ulcer patients. It has no neurological side effects. Rifampin (D) is associated with red-orange discoloration of saliva, tears, and urine but not the color vision problems. Isoniazid (E) is associated with peripheral neuritis in chronic alcoholics and malnourished individuals and requires pyridoxine supplements. It is not associated with optic neuritis. 

Ethionamide is chemically related to isoniazid and also blocks the synthesis of mycolic acids. It is poorly water soluble and available only in oral form. It is metabolized by the liver. 

Resistance to ethionamide as a single agent develops rapidly in vitro and in vivo. There can be low-level cross-resistance between isoniazid and ethionamide. 

Mycobacterium tuberculosis Isoniazid + rifampin + ethambutol + pyrazinamide Streptomycin, moxifloxacin, amikacin, ethionamide, cycloserine, PAS, linezolid... 

A Banerjee, E Dubnau, A Quemard, V Balasubramanian, KS Um, T Wilson, D Collins, G de Lisle, WR Jacobs Jr. inhA, a gene encoding a target for isoniazid and ethionamide in Mycobacterium tuberculosis. Science 263 227-230, 1994. 

Ethionamide This structural analog of isoniazid is believed not to act by the same mechanism. It is effective after oral administration, and is widely distributed throughout the body, including the CSF. Metabolism is extensive. Ethionamide [e thye on AM ide] can inhibit acetylation of isoniazid (Figure 33.7). The urine is the main route of excretion. Adverse effects that limit its use include gastric irritation, hepatotoxicity, peripheral neuropathies, and optic neuritis. Isoniazid... 

Sharma GS, Gupta PK, Jain NK, Shanker A, Nanawati V. Toxic psychosis to isoniazid and ethionamide in a patient with pulmonary tuberculosis. Tubercle 1979 60(3) 171-2. 

Schwartz WS. Comparison of ethionamide with isoniazid in original treatment cases of pulmonary tuberculosis. XIV. A report of the Veterans Administration—Armed Forces cooperative study. Am Rev Respir Dis 1966 93(5) 685-92. 

Several currently used TB drugs target the biosynthesis of the unique mycobacterial cell wall structures (O Fig. 23). Ethambutol is an arabinosyltransferase inhibitor [305], and mycolic acid synthesis is targeted by several commonly used antituberculosis drugs, including isoniazid, ethionamide, isoxyl, thiolactomycin, and triclosan. In addition, pyrazinamide was shown to inhibit the s)mthesis of mycolic acid precursors [306]. 

Ethionamide, USP. 2-Ethylthioisonicotinamide (Trec-ator SC) occurs as a yellow crystalline material that is. sparingly soluble in water. This nicotinamide has weak bacterio-.static activity in vitro but. because of its lipid solubility, is effective in vivo. In contrast to the isoniazid series. 2-substitution enhances activity in the thioisonicotinamide. series. 

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