• Tuberculosis and Respiratory Diseases
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• v.80 no.3
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• pp.255-264
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• 2017

Background:N-acetyl transferase (NAT) inactivates the pro-drug isoniazid (INH) to N-acetyl INH through a process of acetylation, and confers low-level resistance to INH in Mycobacterium tuberculosis (MTB). Similar to NAT of MTB, NAT2 in humans performs the same function of acetylation. Rapid acetylators, may not respond to INH treatment efficiently, and could be a potential risk factor, for the development of INH resistance in humans. Methods: To understand the contribution of NAT of MTB and NAT2 of humans in developing INH resistance using in silico approaches, in this study, the wild type (WT) and mutant (MT)-NATs of MTB, and humans, were modeled and docked, with substrates and product (acetyl CoA, INH, and acetyl INH). The MT models were built, using templates 4BGF of MTB, and 2PFR of humans. Results: On the basis of docking results of MTB-NAT, it can be suggested that in comparison to the WT, binding affinity of MT-G207R, was found to be lower with acetyl CoA, and higher with acetyl-INH and INH. In case of MT-NAT2 from humans, the pattern of score with respect to acetyl CoA and acetyl-INH, was similar to MT-NAT of MTB, but revealed a decrease in INH score. Conclusion: In MTB, MT-NAT revealed high affinity towards acetyl-INH, which can be interpreted as increased formation of acetyl-INH, and therefore, may lead to INH resistance through inactivation of INH. Similarly, in MT-NAT2 (rapid acetylators), acetylation occurs rapidly, serving as a possible risk factor for developing INH resistance in humans.

• Tuberculosis and Respiratory Diseases
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• v.63 no.2
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• pp.128-138
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• 2007

Backgrounds: Mutations of katG and inhA (ORF and promoter) are known to be related to isoniazid (INH) resistance of Mycobacterium tuberculosis. Because reports on these mutations in Korean isolates are limited (i.e. only the frequency of katG codon 463 was evaluated.), we tried to know the kinds of mutations of two genes and their frequencies in INH resistant Korean M. tuberculosis strains. Methods: PCR was performed to amplify katG (2,223 bp), inhA ORF (-77~897, 975 bp), and inhA promoter (-168~80, 248 bp) from 29 multidrug resistant M. tuberculosis (MDR-TB) DNAs prepared by bead beater-phenol method. Their sequences were determined and analyzed by ABI PRISM 3730 XL Analyzer and MegAlign package program, respectively. Results: All of the isolates had more than one mutation in katG or inhA gene. Twenty seven (93%) of 29 tested strains had katG mutations, which suggests that katG is a critical gene determining INH resistance of M. tuberculosis. Amino acid substitutions, such as Arg463Leu and Ser315Thr, due to point mutations of the katG were the most frequent (62.1% and 55.2%) mutations. In addition, deletion of the katG gene was frequently observed (17.2%). Analyzed Korean MDR-TB isolates also had variable inhA mutations. Point mutation of inhA promoter region, such as -15 ($C{\rightarrow}T$) was frequently found. Substitution of amino acid (Lsy8Asn) due to point mutation ($AAA{\rightarrow}AAC$) of inhA ORF was found in 1 isolate. Interestingly, 14 point mutated types that were not previously reported were newly found. While four types resulted in amino acid change, the others were silent mutations. Conclusions: Although it is not clear that the relationship of these newly found mutations with INH resistance, they show marked diversity in Korean MDR-TB strains. It also suggests their feasibility as a molecular target to supplement determining the INH resistance of clinical isolates because of the possible existence of low-level INH resistant strains.

• Journal of Pharmaceutical Investigation
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• v.9 no.3
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• pp.1-8
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• 1979

The main route of metabolism of isonicotinic acid hydrazid (INH) in man is its conjugation with acetyl coenzyme A to form acetyl-INH. The reaction is catalyzed by an N-acetyl transferase in the liver. The acetylated drug can be excreted by the kidney more efficiently than INH, and the biological half-life of the drug in the body depends upon how rapidly the drug can be acetylated. This report measured the concentration of INH in the blood of 147 individuals 6 hours after they received a standard dose (9.8mg/kg) and plotted the data as a frequeney distribution hiotogram. There was bimodality, with a mean for one subpopulation at approximately $0.6{\sim}0.8\;mcg/ml.$, and a mean for the other subpopulation between 2.8 and 4.0mcg/ml. As might be expected slow acetylators of INH are more likely to develop a cumulative toxicity to the drug. The principle ,toxicity to INH is a peripheral neuritis but this adverse effect can be prevented by given extra pyridoxin to the patients, and the vitamin does not alter the antitubercular activity of INH. This report carried out that pyridoxine does not alter the ratio of free INH to the total INH in blood.

• Biomedical Science Letters
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• v.11 no.4
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• pp.455-463
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• 2005

Resistance to isoniazid (INH), which is one of the most important drugs in Mycobacterium tuberculosis chemotherapy, has been associated with mutations in genes encoding the mycobacterial catalse-peroxidase (katG), the enoyl acyl carrier protein (ACP) reductase (inhA), alkyl hydroperoxide reductase (ahpC), beta-ketoacyl acyl carrier protein synthase (kasA), and NADH dehydrogenase (ndh). In this study, we examined INH-resistance related genes in 50 INH-resistant and 24 INH-susceptible isolates by PCR-sequence analysis. In brief, mutations at the katG gene were found at codon 315 alone (2/50), at codon 463 alone (19/50), and both at 315 and 463 (29/50). However, while mutations at codon 315 were only detected in INH-resistant isolates, mutations at codon 463 were also detected in INH-susceptible isolates indicating mutations at 463 alone do not seem to confer resistance to INH. Similar to the case of katG 463, some of inhA mutations were also found among INH-susceptible isolates. For example, whereas mutations at 8 upstream of the start codon (UPS) and 15 UPS of the inhA gene were detected only in INH-resistant isolates, mutations at 101, 115, and 125 UPS were detected only in INH-susceptible isolates. Many different kinds of mutations were detected in INH­resistant isolates at ahpC, oxyR gene, and intergenic region of the oxyR-ahpC genes. Howerver, the mutations were not found oxyR and the intergenic regions in INH-susceptible isolates. No mutations were found at either kasA or at ndh gene among INH-resistant isolates. In conclusion, some of mutations such as katG 315, inhA promotor region, and oxyR-ahpC seem to be strongly related to INH-resistance. Currently we are developing a molecular diagnostic method based on these results.

• Journal of the Korean Chemical Society
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• v.53 no.1
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• pp.17-26
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• 2009

Hydrazones of isonicotinic acid hydrazide, viz., N-isonicotinamido-furfuralaldimine (INH-FFL), N-isonicotnamido-cinnamalidine (INH-CIN) and N-isonicotnamido-3',4',5'-trimethoxybenzaldimine (INH-TMB) were prepared by reacting isonicotinic acid hydrazide with respective aromatic aldehydes, i.e., furfural, cinnamaldehyde or 3,4,5-trimethoxy-benzaldehyde. A new series of fifteen complexes of cobalt(II) with these new hydrazones, INH-FFL, INH-CIN and INH-TMB, were synthesized by their reaction with cobalt(II) salts. The infrared spectral data reveal that hydrazone ligands behave as a bidentate ligand with N, O donor sequence towards the $Co^{2+}$ ion. The complexes were characterized on the basis of elemental analysis, magnetic susceptibility, conductivity, infrared and electronic spectral measurements. Analytical data reveal that the complexes have general composition [Co($L)_2X_2]\;and\;[Co(L)_3](ClO_4)_2$ where L= INH-FFL, INH-CIN or INH-TMB and X = $Cl^-,{NO_3}-,\;NCS^-\;or\;CH_3COO^-.$ The thermal behaviour of the complexes were studied using thermogravimetrictechnique. Electronic spectral results and magnetic susceptibility measurements are consistent with the adoption of a six-coordinate geometry for the cobalt(II) chelates. The antimicrobial properties of cobalt(II) complexes and few standard drugs have revealed that the complexes have very moderate antibacterial activities.

• Tuberculosis and Respiratory Diseases
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• v.82 no.2
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• pp.143-150
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• 2019

Background: The purpose of this study was to analyze the relationship between the gene mutation patterns by the GenoType MTBDRplus (MTBDRplus) assay and the phenotypic drug susceptibility test (pDST) results of isoniazid (INH) and prothionamide (Pto). Methods: A total of 206 patients whose MTBDRplus assay results revealed katG or inhA mutations were enrolled in the study. The pDST results were compared to mutation patterns on the MTBDRplus assay. Results: The katG and inhA mutations were identified in 68.0% and 35.0% of patients, respectively. Among the 134 isolated katG mutations, three (2.2%), 127 (94.8%) and 11 (8.2%) were phenotypically resistant to low-level INH, high-level INH, and Pto, respectively. Among the 66 isolated inhA mutations, 34 (51.5%), 18 (27.3%) and 21 (31.8%) were phenotypically resistant to low-level INH, high-level INH, and Pto, respectively. Of the 34 phenotypic Pto resistant isolates, 21 (61.8%), 11 (32.4%), and two (5.9%) had inhA, katG, and both gene mutations. Conclusion: It is noted that Pto may still be selected as one of the appropriate multidrug-resistant tuberculosis regimen, although inhA mutation is detected by the MTBDRplus assay until pDST confirms a Pto resistance. The reporting of detailed mutation patterns of the MTBDRplus assay may be important for clinical practice, rather than simply presenting resistance or susceptibility test results.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.778-784
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• 2003

N'-(1-alkyl-2,3-dihydro-2-oxo-1H-3-indolyliden)-4-pyridinecarboxylic acid hydrazide derivatives, 3(a-g), were synthesized in a trial to overcome the resistance developed with the therapeutic uses of isoniazid (INH). The lipophilicity of the synthesized derivatives supersedes that of the INH as expressed by Clog p values. The synthesized compounds and INH were tested against bovin, human sensitive and human resist strains of Mycobacterium tuberculosis. Compounds 3a, 3d, 3f and 3g with 1-unsubstituted, 1-propyl, 1-propynyl and 1-benzyl groups respectively exhibited equipotent growth inhibitory activity (MIC 10 $\mu$mol) against the tested strains as compared with INH however the later has no activity against human resist strain. Pharmacokinetic study revealed that the rate and extent of absorption of the tested derivatives (3d and 3f) significantly higher than that of INH (p＜0.05). The relative bioavailabilities ($F_R%$) were 183.15 and 443.25 for 3f and 3d respectively as compared to INH. These results preliminary indicate the possible use of the prepared derivatives for treatment of tuberculosis infections in order to overcome the resistance developed with INH.

• Tuberculosis and Respiratory Diseases
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• v.55 no.5
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• pp.440-448
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• 2003

Background : Development of rapid drug susceptibility testing provides the opportunity for rapid identification of individuals with drug resistant tubercle bacilli, allowing selection of appropriate therapeutic regimens. Methods : A total of 502 drug resistant isolates were subjected to reverse blot hybridization assay to detect mutations within genes (rpoB, katG, inhA, and ahpC) associated with rifampicin (RMP) and isoniazid (INH) resistance. Results : Among the 264 RMP resistant strains ($RMP^R$) tested, the most prevalent mutation was the Ser531Leu seen in 121 strains (46%). The second common mutation occurred in 84 strains (32%) at codon 526. And 27 strains (10%) showed the mutation at codon 516. Among all 469 INH resistant strains ($INH^R$), the katG mutation was responsible for INH. The inhA mutation was present in 88 strains (19%). In 11 isolates (2%), coexisting of the katG and inhA mutations were identified. Reverse hybridization assay successfully detected over 80% of $INH^R$ and over 92% of $RMP^R$ among Korean isolates. CONCLUSION: Reverse hybridization was useful for rapid detection of $INH^R$ and $RMP^R$.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.479-492
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• 1997

Background : Isoniazid(INH) and rifampicin(RFP) are potent antituberculous drugs which have made tuberculous disease become decreasing. In Korea, prescribed doses of INH and RFP have been different from those recommended by American Thoracic Society. In fact they were determined by clinical experience rather than by scientific basis. Even there has been. few reports about pharmacokintic parameters of INH and RFP in healthy Koreans. Method : Oral pharmacokinetics of INH were studied in 22 healthy native Koreans after administration of 300 mg and 400mg of INH to each same person successively at least 2 weeks apart. After an overnight fast, subjects received medication and blood samples were drawn at scheduled times over a 24-hour period. Urine collection was also done for 24 hours. Pharmacokinetics of RFP were studied in 20 subjects in a same fashion with 450mg and 600mg of RFP. Plasma and urinary concentrations of INH and RFP were determined by high-performance liquid chromatography(HPLC). Results : Time to reach peak serum concentration (Tmax) of INH was $1.05{\pm}0.34\;hrs$ at 300mg dose and $0.98{\pm}0.59\;hrs$ at 400mg dose. Half-life was $2.49{\pm}0.88\;hrs$ and $2.80{\pm}0.75\;hrs$, respectively. They were not different significantly(p > 0.05). Peak serum concentration(Cmax) after administration of 400mg of INH was $7.14{\pm}1.95mcg/mL$ which was significantly higher than Cmax ($4.37{\pm}1.28mcg/mL$) by 300mg of INH(p < 0.01). Total clearance(CLtot) of INH at 300mg dose was $26.76{\pm}11.80mL/hr$. At 400mg dose it was $21.09{\pm}8.31mL/hr$ which was significantly lower(p < 0.01) than by 300mg dose. While renal clearance(CLr) was not different among two groups, nonrenal clearance(CLnr) at 400mg dose ($18.18{\pm}8.36mL/hr$) was significantly lower than CLnr ($23.71{\pm}11.52mL/hr$) by 300mg dose(p < 0.01). Tmax of RFP was $1.11{\pm}0.41\;hrs$ at 450mg dose and $1.15{\pm}0.43\;hrs$ at 600mg dose. Half-life was $4.20{\pm}0.73\;hrs$ and $4.95{\pm}2.25\;hrs$, respectively. They were not different significantly(p > 0.05). Cmax after administration of 600mg of RFP was $13.61{\pm}3.43mcg/mL$ which was significantly higher than Cmax($10.12{\pm}2.25mcg/mL$) by 450mg of RFP(p < 0.01). CLtot of RFP at 450mg dose was $7.60{\pm}1.34mL/hr$. At 600mg dose it was $7.05{\pm}1.20mL/hr$ which was significantly lower(p < 0.05) than by 450mg dose. While CLr was not different among two groups, CLnr at 600 mg dose($5.36{\pm}1.20mL/hr$) was significantly lower than CLnr($6.19{\pm}1.56mL/hr$) by 450mg dose(p < 0.01). Conclusion : Considering Cmax and CLnr, 300mg, of INH and 450mg RFP might be sufficient doses for the treatment of tuberculosis in Koreans. But it remains to be clarified in the patients with tuberculosis.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.620-625
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• 2011

A simple, rapid potentiometric back titration of Isoniazid (INH) in the presence of Rifampicin (RIF) in tablets and syrups is described. The method is based on the oxidation of INH by a known excess of copper (II) ion and the back titration of unreacted copper (II) ion potentiometrically with ascorbic acid using a lab-made Copper Based Mercury Film Electrode (CBMFE). The titration conditions have been optimized for the determination of 1.0-10.0 mg of INH in pure and dosage forms. The precision and accuracy of the method have been assessed by the application of lack-of-fit test and other statistical methods. Interference was not caused by RIF and other excipients present in dosage forms. Application of the method for INH assay in tablets and syrups was validated by comparison of the results of proposed method with that of the British Pharmacopoeia (BP) method using F- and t- statistical tests of significance.