Urine Biomarker Assessment of Infant Adherence to Isoniazid Prophylaxis

We assessed adherence in an infant tuberculosis prevention trial in Kenya with a urine isoniazid metabolite-detecting dipstick. Ninety-seven infants had 155 assays performed; 77 (49.7%) were found to be positive despite caregiver-reported adherence. Positive assays were associated with maternal secondary education, HIV suppression and no reported missed doses in past 3 days, suggesting caregiver education and self-medication use influenced infant adherence.

Point-of-care test to monitor adherence to anti-tuberculous treatment

Background: In the fight against the global tuberculosis epidemic, it is essential to ensure that patients adhere to the treatment prescribed. As the treatment is given for a minimum of 6 months it is common for patients not to take their drugs regularly. Strategies are therefore needed to assess adherence to treatment. One established method is to examine the patient's urine for the presence of drug metabolites. A rapid point-of-care test would overcome some of the drawbacks associated with currently available methods.

Method: A rapid, safe point-of-care test for isoniazid metabolites (IsoScreen, Surescreen Diagnostics Limited, Derby, UK) has been developed and used to help assess adherence to treatment in a busy clinic for tuberculosis patients in South London.

Results: Urine samples were examined from 191 patients receiving isoniazid, usually in combination with rifampicin and other anti-tuberculous drugs. Isoscreen was positive in 93.2% of patients, suggesting that 6.8% might be poorly adhering to treatment. By contrast, examining the same urine samples for evidence of rifampicin ingestion gave positive results in only 43.5%, due to the fact that this test is only positive for a few hours after drug ingestion.

Conclusion: IsoScreen has been shown to provide a rapid and safe point-of-care test, which contributes to the detection of non-adherence in patients with tuberculosis.

[THE BIOCHEMICAL AND PATHOPHYSIOLOGICAL MARKERS OF CHEMICAL EFFECT ON ORGANISM, THEIR INFORMATIVENESS AND DIAGNOSTIC SIGNIFICANCE]

The sampling of study included 185 examined workers. Out of them 90 work at "Opitnii zavod Neftekhim" (67 females and 23 males) and 95--at "Kaustik" (64 females and 31 males) from various workshops of the given enterprises. To determine biochemical indicators samples of blood, saliva and urine were collected. The study was carried out in concordance with ethic principles of the Helsinki world medical association declaration, 2008 ed. with receiving written consent of patient to participate in study.

Adherence to self-administered tuberculosis treatment in a high HIV-prevalence setting: a cross-sectional survey in Homa Bay, Kenya

Background

Good adherence to treatment is crucial to control tuberculosis (TB). Efficiency and feasibility of directly observed therapy (DOT) under routine program conditions have been questioned. As an alternative, Médecins sans Frontières introduced self-administered therapy (SAT) in several TB programs. We aimed to measure adherence to TB treatment among patients receiving TB chemotherapy with fixed dose combination (FDC) under SAT at the Homa Bay district hospital (Kenya). A second objective was to compare the adherence agreement between different assessment tools.

Methods

We conducted a cross-sectional survey amongst a series of new TB patients receiving 6 months of standard TB chemotherapy with FDC under SAT. Adherence was assessed at home with urine testing for Isoniazid (INH), pill count, interviewer-administered questionnaire and visual analogue scale (VAS).

Results

In November 2008 and in June 2009, 212 of 279 eligible patients were assessed for adherence. Overall, 95.2% [95%CI: 91.3–97.7] of the patients reported not having missed a tablet in the last 4 days. On the VAS, complete adherence was estimated at 92.5% [95%CI: 88.0–95.6]. INH urine test was positive for 97.6% [95%CI: 94.6–99.2] of the patients. Pill count could be assessed among only 70% of the interviewed patients. Among them, it was complete for 82.3% [95%CI: 75.1–88.1]. Among the 212 surveyed patients, 193 (91.0%) were successfully treated (cured or treatment completed). The data suggest a fair agreement between the questionnaire and the INH urine test (k = 0.43) and between the questionnaire and the VAS (k = 0.40). Agreement was poor between the other adherence tools.

Conclusion

These results suggest that SAT, together with the FDC, allows achieving appropriate adherence to antituberculosis treatment in a high TB and HIV burden area. The use of a combination of a VAS and a questionnaire can be an adequate approach to monitor adherence to TB treatment in routine program conditions.

Risk factors for non-adherence and loss to follow-up in a three-year clinical trial in Botswana

Background

Participant non-adherence and loss to follow-up can compromise the validity of clinical trial results. An assessment of these issues was made in a 3-year tuberculosis prevention trial among HIV-infected adults in Botswana.

Methods and Findings

Between 11/2004–07/2006, 1995 participants were enrolled at eight public health clinics. They returned monthly to receive bottles of medication and were expected to take daily tablets of isoniazid or placebo for three years. Non-adherence was defined as refusing tablet ingestion but agreeing to quarterly physical examinations. Loss to follow-up was defined as not having returned for appointments in ≥60 days. Between 10/2008–04/2009, survey interviews were conducted with 83 participants identified as lost to follow-up and 127 identified as non-adherent. As a comparison, 252 randomly selected adherent participants were also surveyed. Multivariate logistic regression analysis was used to identify associations with selected risk factors. Men had higher odds of being non-adherent (adjusted odds ratio (AOR), 2.24; 95% confidence interval [95%CI] 1.24–4.04) and lost to follow-up (AOR 3.08; 95%CI 1.50–6.33). Non-adherent participants had higher odds of reporting difficulties taking the regimen or not knowing if they had difficulties (AOR 3.40; 95%CI 1.75–6.60) and lower odds associated with each year of age (AOR 0.95; 95%CI 0.91–0.98), but other variables such as employment, distance from clinic, alcohol use, and understanding study requirements were not significantly different than controls. Among participants who were non-adherent or lost to follow-up, 40/210 (19.0%) reported that they stopped the medication because of work commitments and 33/210 (15.7%) said they thought they had completed the study.

Conclusions

Men had higher odds of non-adherence and loss to follow-up than women. Potential interventions that might improve adherence in trial participants may include:targeting health education for men, reducing barriers, clarifying study expectations, educating employers about HIV/AIDS to help reduce stigma in the workplace, and encouraging employers to support employee health.

Trial Registration

ClinicalTrials.gov NCT00164281

The reliability and practicality of the Arkansas method assay of isoniazid adherence

The Arkansas method (AM) for isoniazid (INH) metabolite detection is a relatively inexpensive, simple, objective measure of adherence. The purpose of the study was to explore whether variations in urine sample handling and storage will produce accurate assay outcomes. Participants were a convenience sample of 28 adults and adolescents prescribed INH for latent tuberculosis infection. Participants provided one sample to test effects of the following: mixing processes; durations at room temperature, in a refrigerator, or frozen; and effects of freeze/thaw cycles on AM outcomes. No manipulations had a discernible impact on outcomes with concordant positive rates from 85% to 100%. Concordance rates of manipulated samples did not appear to differ from rates of norm samples. Results suggest that urine samples can withstand a variety of manipulations in both handling and storage without affecting the accuracy of AM assay results. These findings have important implications for providers of treatment and researchers and provide the impetus for both to examine the potential of using the AM of INH metabolite testing as a measure of medication adherence.

Point-of-care Arkansas method for measuring adherence to treatment with isoniazid

We evaluated the accuracy of a point-of-care test designed to measure adherence to isoniazid (INH) preventive therapy in a hospital setting in Rio de Janeiro, Brazil. Patients on treatment with daily INH and patients not receiving INH were included. Sensitivity and specificity of the test were 84%/98% at the first minute, and 95%/98% at the fifth minute, respectively. Among smokers, sensitivity and specificity was reduced (80%/89% at the fifth minute, respectively), but only 17% smoked. This test accurately detected INH metabolites 24h following directly observed INH intake, though sensitivity and specificity may be compromised by tobacco smoke exposure.

Evaluation of the Arkansas method of urine testing for isoniazid in South Africa

SETTING

A South African hospital serving gold mine employees.

OBJECTIVE

To determine the sensitivity and specificity of the Arkansas method for detecting isoniazid (INH) metabolites among South African adults and to examine the effect of smoking status on positive results.

DESIGN

Urine specimens were collected from in-patients taking INH as part of tuberculosis treatment at 6, 12 and 24 h after a directly observed 300 mg oral dose. As a control group, a single urine specimen was collected from surgical in-patients not taking INH. Specimens were tested for INH using a commercially available dipstick.

RESULTS

A total of 153 patients on INH and 60 controls were recruited. The sensitivity of the test was 93.3% (95%CI 88.1-96.8) at 6 h post INH, 93.4% (95%CI 88.2-96.8) at 12 h and 77% (95%CI 69.1-83.7) at 24 h. The specificity of the test was 98.3% (95%CI 91.1->99.9). There was no association between smoking status and colour change of positive results.

CONCLUSIONS

This test is a useful method of monitoring adherence to TB treatment or preventive therapy among South Africans. However, it is less than 100% sensitive, especially with increasing time post dose, which should be taken into consideration when interpreting results for individual patients.

Urine levels of rifampicin & isoniazid in asymptomatic HIV-positive individuals

BACKGROUND & OBJECTIVE

AIDS and its associated gastrointestinal complications may impair the absorption of anti-tuberculosis (TB) drugs. Impaired absorption of anti-TB drugs could lead to low drug exposure, which might contribute to acquired drug resistance and reduced effectiveness of anti-TB treatment. The aim of this study was to obtain information on the status of absorption of rifampicin (RMP) and isoniazid (INH) in asymptomatic HIV- positive individuals, who are less immunocompromised. The D-xylose absorption test was also carried out to assess the absorptive capacity of intestive.

METHODS

The absorption of RMP, INH and D-xylose was studied in 15 asymptomatic HIV-positive individuals with CD4 cell counts>350 cells/mm3 and 16 healthy volunteers, after oral administration of single doses of RMP (450 mg), INH (300 mg) and D-xylose (5 g). Urine was collected up to 8 h after drug administration. Percentage dose of the drugs and their metabolites and D-xylose excreted in urine were calculated.

RESULTS

A significant reduction in the urinary excretion of INH and D-xylose in HIV-positive persons compared to healthy volunteers was observed. The per cent dose of RMP and its metabolite, desacetyl RMP was also lower in HIV-positive persons compared to healthy volunteers, but this difference was not statistically significant.

INTERPRETATION & CONCLUSION

Decreased urinary excretion of D-xylose and INH are suggestive of intestinal malabsorption in HIV-positive individuals. HIV infection could cause malabsorption of anti-TB drugs even at an early stage of the disease. The clinical implications of these findings need to be confirmed in larger studies.

Flow-injection chemiluminescence sensor for determination of isoniazid in urine sample based on molecularly imprinted polymer

In this paper, molecularly imprinted polymer (MIP) of isoniazid is synthesized through thermal radical copolymerization of metharylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of isoniazid template molecules. A novel flow injection chemiluminescence sensor for isoniazid determination is developed by packing the isoniazid-MIP into the flow cell as recognition elements. Isoniazid could be selectively adsorbed by the MIPs and the adsorbed isoniazid was sensed by its great enhancing effect on the weak CL reaction between luminol and periodate which were mixed in the flow cell. The enhanced CL intensity is linear in the range 2x10(-9) to 2x10(-7) g/mL and the detection limit is 7x10(-10) g/mL (3sigma) isoniazid with a relative standard deviation 2.8% (n=9) for 8x10(-8) g/mL. The sensor is reversible and reusable. It has a great improvement in sensitivity and selectivity for CL analysis. As a result, the sensor has been successfully applied to determination of isoniazid in human urine. At the same time, the binding characteristic of the polymer to isoniazid was evaluated by batch method and the dynamic method, respectively.

Adherence with isoniazid for prevention of tuberculosis among HIV-infected adults in South Africa

BACKGROUND

Tuberculosis (TB) is the most common opportunistic infection in HIV-infected adults in developing countries. Isoniazid (INH) is recommended for treatment of latent TB infection, however non-adherence is common. The purpose of this study was to apply in-house prepared isoniazid (INH) urine test strips in a clinical setting, and identify predictors of positive test results in an adherence questionnaire in HIV-infected adults taking INH for prevention of TB.

METHODS

Cross-sectional study of adherence using a questionnaire and urine test strips for detection of INH metabolites at two hospitals in Pietermaritzburg, South Africa. Participants were aged at least 18 years, HIV positive, and receiving INH for prevention of tuberculosis disease. Univariate and multivariate analyses are used to identify factors relevant to adherence.

RESULTS

301 consecutive patients were recruited. 28% of participants had negative urine tests. 32 (37.2%, 95% CI25.4, 45.0) of the 86 patients who received INH from peripheral pharmacies said the pharmacy had run out of INH at some time, compared with central hospital pharmacies (p = 0.0001). In univariate analysis, a negative test was associated with self-reported missed INH doses (p = 0.043). Each 12-hour increment since last reported dose increased the likelihood of a negative test by 34% (p = 0.0007). Belief in INH safety was associated with a positive test (p = 0.021). In multivariate analysis, patients who believed INH is important for prevention of TB disease were more likely to be negative (p = 0.0086).

CONCLUSION

Adequate drug availability at peripheral pharmacies remains an important intervention for TB prevention. Key questions may identify potentially non-adherent patients. In-house prepared urine tests strips are an effective and cheap method of objectively assessing INH adherence, and could be used an important tool in TB control programs.

Monitoring the ingestion of anti-tuberculosis drugs by simple non-invasive methods

This investigation retrospectively assessed inexpensive non-invasive qualitative methods to monitor the ingestion of anti-tuberculosis drugs isoniazid, rifampicin and rifapentine. Results showed that commercial test strips detected the isoniazid metabolites isonicotinic acid and isonicotinylglycine as efficiently as the isonicotinic acid method in 150 urine samples. The presence of rifamycins in urine samples (n=1085) was detected by microbiological assay techniques and the sensitivity compared to the n-butanol extraction colour test in 91 of these specimens. The proportions detected by the two methods were significantly different and the sensitivity of the n-butanol procedure was only 63.8% (95% CL 51.2-76.4%) as compared to that of the superior microbiological method. Final validation (n=691) showed that qualitative assays measure isoniazid and rifamycin ingestion with an efficiency similar to high-performance liquid chromatography. The qualitative procedures may therefore be valuable in clinical trials and in tuberculosis clinics to confirm drug ingestion.

Patient knows best: blinded assessment of nonadherence with antituberculous therapy by physicians, nurses, and patients compared with urine drug levels

BACKGROUND

Adherence with therapy is a wide spectrum of behavior rather than a categorical state. While extreme nonadherence is readily apparent, it is rare compared to lesser degrees of nonadherence, which are difficult to predict.

AIMS

To compare the accuracy of doctor, nurse, and patient prediction of adherence with antituberculous therapy with urine isoniazid levels.

METHODS

A prospective, blinded clinical study was conducted, comparing adherence to antituberculous therapy as reported by patients, doctors, and nurses with urine isoniazid levels. We studied 173 patients with active tuberculosis (TB) recruited over 3 years in two TB clinics in Victoria, Australia. Adherence was defined as six random urine isoniazid (INH) levels being >0. Blinded assessment of adherence was completed by doctors, nurses, and patients. Lid opening and closing of computerized pill bottles were measured in a random subsample.

RESULTS

Of 173 patients, the rate of nonadherence was 24% (41/173) by urine INH, 54% (93/173) by patient self-report, 11% (19/173) by doctor assessment, and 7% (12/173) by nurse assessment. The sensitivity of prediction of nonadherence was 76% for patient self-report, 24% for doctor assessment, and 19% for nurse assessment. The 10 patients who used computerized pill bottles were all (100%) noncompliant at some stage.

CONCLUSION

Nonadherence is common and poorly predicted by doctors and nurses, even those with extensive experience in treating TB. Contrary to popular belief, patient self-report is more reliable than doctor or nurse assessment of nonadherence. As clinicians, asking patients about adherence may be more valuable than attempting to judge for ourselves.

Electrochemical behavior of the antituberculosis drug isoniazid and its square-wave adsorptive stripping voltammetric estimation in bulk form, tablets and biological fluids at a mercury electrode

Isoniazid, pyridine-4-carboxylic acid hydrazide, is an antituberculosis-agent, which is used to prevent the development of clinical tuberculosis. A validated square-wave adsorptive cathodic stripping voltammetric procedure for the trace determination of the bulk drug at the hanging mercury drop electrode (HMDE) has been developed. Under the optimized conditions, (accumulation potential=-0.9 V, accumulation time=50-300 s, scan increment=8 mV, pulse-amplitude=25 mV, frequency=120 Hz and acetate buffer at pH 5.5) isoniazed generated two irreversible cathodic peaks. The first peak current showed a linear dependence with the drug concentration over the range 5 x 10(-10)-21 x 0(-6) M. The mean percentage recoveries, based on the average of five replicate measurements, for 7 x 10(-9) and 5 x 10(-8) M isoniazid were 97.71+/-2.93 and 99.76+/-0.77, respectively. The achieved limits of detection (LOD) and quantitation (LOQ) were 1.18 x 10(-10) and 3.93 x 10(-10) M isoniazid, respectively. The procedure was applied to the assay of the drug in tablets (Isocid and T.B. Zide), spiked human serum and urine with mean percentage recoveries of 97.81+/-1.49, 97.45+/-2.09, and 97.08+/-1.06, respectively. The limits of detection of 1.47 x 10(-9) and 2.4 x 10(-8) M, and quantitation of 4.9 x 10(-9) and 8 x 10(-8) M drug in human serum and urine, respectively, were achieved. The mean values of the various pharmackinetic parameters of isoniazid (C(max), T(max), t(1/2), AUC, and K(e)), estimated from analysis of plasma of two volunteers by means of the proposed procedure were similar to literature values.

Increasing Latino adolescents' adherence to treatment for latent tuberculosis infection: a controlled trial

OBJECTIVES

We sought to determine the efficacy of coaching Latino adolescents with latent tuberculosis infection to adhere to isoniazid treatment.

METHODS

Participants (n = 286) were randomly assigned to adherence coaching, attention control, or usual care groups. Adherence was measured via interviews and validated with urine assays.

RESULTS

Coaching resulted in significant increases in adherence compared with attention and usual care groups. Bicultural adolescents were more likely to be adherent than those most or least acculturated. Age and risk behavior were negatively related to adherence.

CONCLUSIONS

Coaching can increase Latino adolescents' adherence to treatment for latent tuberculosis infection and should contribute to tuberculosis control for adolescents at high risk of contracting the disease.

A randomised controlled clinical trial of the efficacy of family-based direct observation of anti-tuberculosis treatment in an urban, developed-country setting

SETTING

A randomised, controlled clinical trial of the effectiveness of a family-based programme of directly observed treatment (DOT) for tuberculosis.

METHODS

TB patients seen in Victoria, Australia, were randomly allocated to DOT observed by a family member (FDOT), or to standard supervised but non-observed therapy (ST). The outcome measure was compliance, measured by blinded testing of isoniazid levels in urine. An intention-to-treat analysis was used.

RESULTS

Of 173 patients, 87 were allocated to FDOT and 86 to ST. Only 58% in the FDOT group were able to receive FDOT, the major reason being living alone and not having a family member to observe treatment. The rate of non-compliance was 24% (41/173), with no significant difference between FDOT (22/87) and ST (19/86). No clinical or socio-demographic variable predicted compliance.

CONCLUSIONS

We were unable to demonstrate a benefit of FDOT in an urban, industrialised country setting. FDOT may be more appropriate in developing countries, where extended family support is often available and the burden of TB is much higher. Poor compliance and the difficulty in predicting non-compliance shown in this study highlights the need for DOT for all TB patients.

Low level of compliance with tuberculosis treatment in children: monitoring by urine tests

Patient compliance should be ensured in an effective tuberculosis control programme. We measured patient compliance by detecting antituberculous drugs in the urine of 237 outpatients receiving one to three antituberculous drugs. Positive controls were 20 hospitalised patients, supervised to receive isoniazid (INH), rifampicin (RIF) and pyrazinamide (PZA), and negative controls were not on any drugs. Among the 237 study patients, only 67% were found to be taking the appropriate treatment and 8% had taken none. We conclude that a remarkable number of patients (33%) were non-compliant with treatment. The detection of antituberculous drugs in the urine is a quick, simple and inexpensive means of measuring adherence to treatment. Unless directly observed therapy (DOT) is adopted, we recommend routine urine testing for antituberculous drugs to identify defaulting patients.

Use of the urine color test to monitor compliance with isoniazid treatment of latent tuberculosis infection

STUDY OBJECTIVE

To apply the Arkansas color method in order to evaluate drug compliance and factors that can predict treatment adherence in patients being treated for latent tuberculosis infection (LTBI) with a single daily dose of isoniazid (INH).

DESIGN

Prospective study of adherence of 105 patients aged 1 to 75 years who were treated with a single daily dose of INH for LTBI.

INTERVENTIONS

Patients or their parents were interviewed regarding parameters that may affect compliance. Urine samples were collected and tested for INH metabolites with the Arkansas color method.

RESULTS

Nonadherence to treatment was found in 28.5% of patients. There was no statistically significant correlation among the following parameters: gender; age; diagnosis; mode of administration (self or parents); duration of treatment; dose of INH per weight; or interval since last intake of dose. Twenty-six patients were randomly checked for treatment adherence on two separate visits, and nonadherent patients were informed immediately and their condition was fully explained to them. Five of six patients who were nonadherent in the first visit and were examined twice became adherent in the second visit. Three of 20 patients who were adherent in the first visit became nonadherent.

CONCLUSION

Almost one third of the patients who received LTBI treatment with INH were nonadherent to treatment. No factor was found to predict adherence. The Arkansas method can be used by the family physician and is a simple, immediate method to follow-up patients with LTBI who are treated with INH.

The value of urine testing for verifying adherence to anti-tuberculosis chemotherapy in children and adults in Uganda

SETTING

Mulago Hospital, Kampala, Uganda.

OBJECTIVE

To evaluate the usefulness of urine dipsticks for monitoring adherence to anti-tuberculosis chemotherapy.

DESIGN

In-house urine dipsticks for detection of isoniazid (INH) metabolites were compared to commercial test strips. The value of n-butanol to detect rifampicin was compared to coloration of the urine. Non-adherence was assessed through a questionnaire and reviews of the Mulago Hospital TB register.

RESULTS

Urine was obtained from 236 patients (127 adults and 109 children) on daily chemotherapy. Using commercial test strips as standard, the sensitivity of in-house urine dipsticks was 99.5% and specificity was 96.4%. The sensitivity and the specificity of n-butanol and of coloration of urine to detect rifampicin were low (64.0% and 54.9%, and 85.5% and 64.8%, respectively). Fifty patients (21.2%) admitted non-adherence to treatment during the previous month. An additional 15 (6.8%) were detected through urine testing. Of 911 patients in the TB register of Mulago Hospital who had started treatment in the first 3 months of 2000, 39.7% did not complete their treatment. Two-thirds of these had discontinued treatment in the first 2 months.

CONCLUSION

In-house INH test strips are as effective as commercially available strips for detecting isoniazid in the urine. They are a simple tool for monitoring adherence. Adherence to anti-tuberculosis chemotherapy as determined by the use of isoniazid test strips and review of the TB register showed poor compliance. Tests for rifampicin are less sensitive and specific.

[Determination of isoniazid in blood and urine samples by reversed-phase high performance liquid chromatography]

For the purpose of more accurate and rapid analysis of isoniazid in body fluid samples, a reversed-phase high performance liquid chromatographic (HPLC) method was developed. Vanillin, being as a derivatizing reagent, was added to the plasma and urine samples when they were pretreated. Isoniazid and vanillin reacted to form isonicotinoyl hydrazone which was separated and detected. The pretreatment method of sample, the linear range, the precision, and the recovery of isoniazid were investigated by using human's plasma and urine spiked with standard isoniazid. The linear range was 0.2 mg/L- 12.0 mg/L (for plasma, r =0.999 6; for urine, r = 0.999 4). The detection limit was 0.2 mg/L. The intra-day and inter-day precisions of assay for isoniazid were 2.3% - 2.6% and 3.8% - 4.0% (n = 5) for plasma, 1.3% - 4.0% and 2.1% - 3.9% (n = 5) for urine respectively. The average recoveries of isoniazid were from 96.5% to 99.8% in plasma and from 96.3% to 99.4% in urine. The HPLC method has been used to investigate the concentration of isoniazid in the volunteer's plasma. The quantitative analysis of isoniazid in plasma was not interfered by impurities, the metabolites of isoniazid and the derivatizing reagent residue. This analytical method for isoniazid is sensitive, rapid and convenient. It is suitable for the analysis of toxics in forensic samples, the detection of drug concentration in clinical medicines and pharmacokinetic studies.

Urine testing to monitor adherence to TB preventive therapy

This study examined the validity of the Arkansas urine test. One hundred ninety-four adolescents submitted an unannounced urine specimen monthly (for 6 to 8 months). Duplicate specimens were blindly tested with high agreement (kappa >90%). Sensitivity and specificity were estimated. In 68% of test runs, adolescents recalled taking INH within 24 hr of specimen collection. For recall intervals of 24, 48, and 72 hr, sensitivity was 87, 85, and 83%, respectively. Females were less likely to test positive when INH was taken within the previous 24 hr (sensitivity 84 versus 92% males). Specificity was 57, 91, and 95% at 24, 48, and 72 hr, respectively. The Arkansas urine test was practical to use, and results correlated well with self-reported adherence to INH for treatment of latent tuberculosis infection (LTBI), over several months of follow-up. The test may be useful as part of an adherence-monitoring program when used in conjunction with self-reported measures.

A simplified method for detecting isoniazid compliance in patients receiving antituberculosis chemotherapy

The objective of this study was to develop a new simplified method using thin-layer chromatography (TLC) for determining isoniazid (INH) compliance in patients receiving antituberculosis chemotherapy. TLC was performed on silica gel plates using a standard solution of INH and acetylisoniazid (AcINH) and ethyl acetate-methanol (70:30 v/v) as the developing solvent. The spots of compound were detected by iodine. In the human study, fractional urine samples were collected over 24 hours from 4 healthy human subjects genotyped for NAT2* and to whom 400 mg of INH were administered orally. These samples were used for TLC analysis. The results of TLC were compared with those of high-performance liquid chromatography (HPLC). This method indicated good separation between INH and AcINH in standard solutions. The detection limits for INH and AcINH (applied volume; 20 microl of standard solution) were 2.2 nmole and 5 nmole, respectively, as detected by iodine. In the human study, the INH spot in urine was not detected on the TLC plate, except in one sample over the 0- to 4-hour period from 1 volunteer. However, the AcINH spot was detected in all urine samples from all volunteers. The total experimental time from application of the urine sample to analysis on TLC was 30 minutes. The results suggest that this method for detecting AcINH on TLC is an excellent, convenient, and simple method for determining INH compliance in patients receiving standard antituberculosis chemotherapy regimen or INH preventative therapy, regardless of the patient's NAT2* genotype.

Salivary and urinary excretion and plasma-saliva concentration ratios of isoniazid in the presence of Co-administered ciprofloxacin

Salivary and urinary excretion and plasma-saliva concentration ratios of isoniazid (INH) in the absence and presence of ciprofloxacin (CP) were investigated in healthy female volunteers. Results obtained indicated an absorption form of interaction between INH and CP. This led to delay in gastric emptying and onset of absorption of INH in the upper part of the gastrointestinal tract, resulting in a corresponding delay in the onset of salivary and urinary excretion of the drugs. There was a 1-hour reduction in the time to attain peak saliva concentration of INH (tmax), an insignificant difference in peak saliva concentration (Cmax), and a significant (P = 0.05) increase in AUC(0-24h) of INH in the presence of CP. Cumulative amount of INH excreted in the urine increased approximately 38% in the presence of CP. The calculated plasma-saliva concentration ratios of INH were reduced in the presence of CP and were slightly lower than the experimental values. This indicates increased amount of the drug secreted into saliva in the presence of CP and possible buccal partitioning of the drug. Overall, results of the current study indicate that CP delayed the onset but not the extent of INH absorption. Therefore, concurrent administration of the two drugs was considered relatively safe, and the absorption interaction that may have occurred may not be of reasonable clinical consequence.

Can guardians supervise TB treatment as well as health workers? A study on adherence during the intensive phase

SETTING

In sub-Saharan Africa, tuberculosis (TB) has increased over the last two decades due to the human immunodeficiency virus pandemic. In Malawi, 20630 new TB patients were notified to the National Tuberculosis Programme in 1996, a fourfold increase since 1986. Due to this increase in cases and lack of resources (both human and monetary) it is becoming more difficult to ensure directly observed treatment (DOT) in the TB wards.

METHODS

In Ntcheu district, Malawi, a new TB regimen was introduced from April 1996 in which patients received supervised treatment by either a health worker or a guardian (i.e., family member). Adherence to the different treatment options was measured by form checks, tablet counts, and tests for detecting isoniazid in the urine. Adherence was measured at 2, 4 and 8 weeks after onset of TB treatment.

RESULTS

Overall adherence rate was 95-96%. Inpatients showed the highest adherence rates. Patients on guardian-based DOT (GB-DOT) (n = 35) showed 94% adherence, while patients on health centre based DOT (n = 40) showed more non-adherent behaviour: 11% according to monitoring forms, 14% according to tablet counts and 16% according to urine tests.

DISCUSSION

The results suggest that decentralised care is a feasible option for anti-tuberculosis treatment and that guardians can supervise TB treatment just as well as health workers during the intensive phase of TB treatment.

The potential use of urinary excretion data for assessing the relative bioavailability of rifampicin in fixed dose combination anti-tuberculosis formulations

SETTING

The perceived need for simple, non-invasive methods of assessing the relative bioavailability of rifampicin in fixed-dose combination (FDC) anti-tuberculosis formulations.

OBJECTIVE

To compare the performance of methods based on urinary excretion data with those utilising plasma concentration-time profiles to assess the relative bioavailability of rifampicin in combined and single-drug formulations.

DESIGN

A two-period randomised crossover bioequivalence study in healthy male volunteers with a 1 week washout period between treatments. Plasma rifampicin concentrations were measured at 0, 1, 2, 4, 6 and 8 hours after each drug administration using a high performance liquid chromatography (HPLC) method. The rifampicin and desacetylrifampicin content of complete urinary collections made from 0-4 and 4-8 hours after dosage were determined using both the HPLC and a much simpler colorimetric procedure.

RESULTS

There was good agreement between the relative bioavailability of the formulations using plasma and urinary excretion data, although the precision of the urinary-based estimates was slightly less than those derived from the plasma findings. There was also good agreement between the HPLC and colorimetric estimates of the combined urinary excretion of rifampicin plus desacetylrifampicin.

CONCLUSIONS

Urinary excretion data may be used for ongoing quality control to confirm that commercial combined rifampicin-containing formulations that were initially shown to be satisfactory continue to be so.

On-column amperometric detection of ofloxacin and pasiniazid in urine by capillary electrophoresis with an improved fractured joint and small detection cell

An improved high-voltage electric field isolating joint and small detection cell have been carefully designed and fabricated. The joint possesses short steady time, high electric conductance efficiency and high performance. The cell is convenient to install and remove the capillaries with and without the joint, as well as to fix, adjust and insert the microelectrode into the detection capillary. Using the joint and the cell, an analytical method for determination of ofloxacin (Oflx) and pasiniazid (Ipa) in urine by capillary electrophoresis with on-column amperometric detection was developed. The calibration lines were linear in the range of 10-100 mg l-1 of Oflx and 1.0-50 mg l-1 of Ipa, respectively. The detection limits were 8.5 mg l-1 of Oflx and 0.80 mg l-1 of Ipa. Their recovery ranged from 101 to 104%. The accuracy and intra-day and inter-day reproducibility of Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Oflx and Ipa in human urine.

Effects of pefloxacin on urinary and salivary concentrations of isoniazid in six healthy female volunteers

The effects of pefloxacin (PFC), a fluoroquinolone antibiotic, on the urinary and salivary concentrations of Isoniazid (INH) were investigated in six healthy female volunteers 19 to 30 years of age. The presence of PFC increased the rate and extent of INH absorption and the rate of its excretion in the urine and saliva. There was an increase in the excretion rate constant (K) and a reduction in the half-life (t1/2) of INH in the presence of PFC. Four of the volunteers had t(1/2) values in the range of 1.55 to 2.43 hours and were considered to be fast acetylators, whereas two subjects with a t(1/2) in the range of 3.36 to 4.41 hours were considered to be slow acetylators. Concurrent administration of INH and PFC may lead to an increased INH toxicity based on the results of the present study.

Bioavailability of rifampicin, isoniazid and pyrazinamide in a triple drug formulation: comparison of plasma and urine kinetics

SETTING

The present study assesses bioavailability indices for rifampicin, isoniazid and pyrazinamide when administered to healthy volunteers separately or in a fixed triple-drug formulation, Rifater 125 SCT.

OBJECTIVE

To compare the pharmacokinetics of rifampicin, isoniazid and pyrazinamide based on their blood concentrations up to 12 hours with the proportions of the doses of the drugs and their metabolites excreted in urine up to 12 hours, and to assess the bioavailability indices for the free and fixed triple drug formulations.

DESIGN

An open cross-over study was conducted in 18 healthy volunteers with normal hepatic and renal functions to whom the drug combinations were administered in free and fixed dose formulations a week apart, to the same subject.

RESULTS

Concentrations of the three drugs/metabolites were assessed in blood and urine. The results indicated the absence of negative pharmacokinetic interactions between the drugs when administered in both the free and the new fixed triple drug formulation.

CONCLUSION

Human bioavailability studies provide direct straightforward information, particularly when studying compounds such as rifampicin and other major anti-tuberculosis drugs. The results of the present study indicate that the pharmacokinetic properties of rifampicin, isoniazid and pyrazinamide as assessed after individual and combined administration do not change when combined in a single pharmaceutical preparation. The bioavailability indices calculated based on plasma concentrations and urinary levels for all three drugs compared well.

A reproducible, simple, and sensitive high-performance capillary electrophoresis method for simultaneous determination of capreomycin, ofloxacin and pasiniazide in urine

Separation and determination of capreomycin (Cp), ofloxacin (Oflx) and pasiniazide (Ipa) in urine by high-performance capillary electrophoresis (HPCE) with 280 nm detection have been studied systematically. The calibration lines were linear in the range of 0.5 approximately 50 mg 1(-1), and the detection limits (S/N = 3) were 0.15, 0.20 and 0.10 mg 1(-1) for Cp, Oflx and Ipa, respectively. The recoveries for these materials from urine were higher than 93.5%. The accuracy and intra- and inter- day reproducibility of Cp, Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Cp. Oflx and Ipa in human urine.

Effects of drug concentration in inner aqueous phase and additives in oleaginous phase on release and bioavailability of isoniazid from multiple emulsion

The effects of drug concentration in internal aqueous phase of stabilized w/o/w emulsion and additives in oleaginous phase on release characteristics of isoniazid were investigated. The release was significantly effected by both of the formulation variables. The release was enhanced initially with increasing concentration of drug in internal aqueous phase followed by a steady release at high concentration of isoniazid. The release declined substantially in the presence of aluminum tristearate, cetostearyl alcohol, and cholesterol, and it increased with egg lecithin and oleic acid in oily phase. The bioavailability was increased with a multiple-emulsion formulation.

Comparison of three composite compliance indices in a trial of self-administered preventive therapy for tuberculosis in HIV-infected Ugandan adults. Uganda-Case Western Reserve University Research Collaboration

Compliance with tuberculosis preventive therapy in a randomized placebo-controlled trial in 2736 HIV-infected Ugandans was measured using urinary isoniazid metabolite testing, clinic attendance, and self-report. Overall, 77% of urine tests were positive, subjects kept 85% of their scheduled visits while on therapy, and 69% reportedly never forgot to take their medication. Different strategies were used for constructing three composite compliance indices in active arms: (1) an unweighted index of the summed scores on scaled compliance measures; (2) a weighted index using weights obtained from a survey of experts on tuberculosis; and (3) a statistically weighted index using principal components analysis. Composite indices were evaluated for reliability, validity, and practical utility. Understanding of the regimen, study arm, subsequent follow-up, tuberculosis status, and urine spot-check result were associated with composite compliance scores. The unweighted index in this study performed as well as the weighted indices.

Attendance versus compliance with tuberculosis treatment in an occupational setting--a pilot study

AIM

To determine the prevalence of non-compliance with tuberculosis treatment at Freegold Mines.

OBJECTIVES

1. To establish the rates of attendance and collection of anti-tuberculosis drugs. 2. To determine prevalence of non-compliance by means of urine tests.

DESIGN

A cross-sectional study conducted over 2 weeks at mine medical stations.

METHOD

Urine samples were collected from tuberculosis patients 3 hours after drug ingestion. Non-compliance was established by testing these samples for rifampicin and/or isoniazid (INH) metabolites. Non-compliance was defined as a negative urine test result for these drugs in participants whose treatment regimens included one or both. Daily attendance and collection of drugs statistics are recorded in the medical station tuberculosis register. The patient rate of adherence was calculated as the observed number of days on which medication had been collected over the expected treatment days in a given period.

RESULTS

Urine test results showed an overall prevalence of non-compliance of 14.6 +/- 3.3%. The study showed that non-compliance with tuberculosis treatment was underestimated by the surveillance data. The rate of non-adherence with treatment established from the formal surveillance procedure was 0.2%. The poor response rate of patients was found to be a major problem and fewer than 40% per day returned to bring urine specimens. The mean prevalences of non-compliance established by rifampicin and INH tests were 19.5 +/- 5.3% and 9.8 +/- 3.9%, respectively, and these were significantly different (Chi 2 = 7.44; P < 0.05). The proportion of false-positive results for INH and rifampicin urine tests were 21% (11/53) and 35% (17/48), respectively, showing that some patients were taking the wrong treatment.

CONCLUSIONS

It is clear that attendance at the clinics does not accurately reflect compliance. Both programme compliance (dispensing of the correct treatment) and patient compliance need to be improved. This has important implications for the new national tuberculosis control policy adopted by the South African government that stresses the importance of directly observed therapy, short-course (DOTS) and a patient-centred approach.

[Evaluation of compliance with antituberculous chemoprophylaxis among recluse population of the Jaen penitentiary center]

BACKGROUND

This study highlights the importance of antitubercular chemoprophylaxis with isoniazid to control and prevent tuberculosis in prisons. The relationship between compliance with the chemoprophylaxis and study factors was evaluated and we examined whether health education given in our prison motivated the prisoners to comply with this treatment.

METHODS

Compliance with chemoprophylaxis using isoniazid by 52 inmates of the Jaén Penal Institution was studied for the period February to May 1995. The dose of isoniazid taken was calculated by means of the spectrophotometric determination of isoniazid metabolites in urine using the Eidus Hamilton method. Likewise, the influence of variables such as sex, HIV infection, legal situation and cultural level on compliance was studied.

RESULTS

Out of 52 inmates, 23 (44.23%) were taking a daily dose of isoniazid that was considered to be effective and 29 inmates (55.77%) were taking less than the effective isoniazid dose for the chemoprophylaxis. With regard to the variables studied, greater compliance with the chemoprophylaxis was recorded among men (sex variable) and those inmates with a higher educational level (cultural level) although no significant differences were found.

CONCLUSIONS

Compliance with the chemoprophylaxis among our inmates is inadequate although it matches similar studies that have been carried out on the prison population. This is not the case for the community population where compliance with chemoprophylaxis is greater. This low compliance forces us to review our current health education programme and to take steps that might increase this degree of compliance such as direct observation of treatment, a system of intermittent treatment, etc.

Isoniazid preventive therapy for tuberculosis in HIV-1-infected adults: results of a randomized controlled trial

OBJECTIVES

To determine the efficacy of isoniazid 300 mg daily for 6 months in the prevention of tuberculosis in HIV-1-infected adults and to determine whether tuberculosis preventive therapy prolongs survival in HIV-1-infected adults.

DESIGN AND SETTING

Randomized, double-blind, placebo-controlled trial in Nairobi, Kenya.

SUBJECTS

Six hundred and eighty-four HIV-1-infected adults.

MAIN OUTCOME MEASURES

Development of tuberculosis and death.

RESULTS

Three hundred and forty-two subjects received isoniazid and 342 received placebo. The median CD4 lymphocyte counts at enrolment were 322 and 346 x 10(6)/l in the isoniazid and placebo groups, respectively. The overall median follow-up from enrolment was 1.83 years (range, 0-3.4 years). The incidence of tuberculosis in the isoniazid group was 4.29 per 100 person-years (PY) of observation [95% confidence interval (CI) 2.78-6.33] and 3.86 per 100 PY of observation (95% CI, 2.45-5.79) in the placebo group, giving an adjusted rate ratio for isoniazid versus placebo of 0.92 (95% CI, 0.49-1.71). The adjusted rate ratio for tuberculosis for isoniazid versus placebo for tuberculin skin test (TST)-positive subjects was 0.60 (95% CI, 0.23-1.60) and for the TST-negative subjects, 1.23 (95% CI, 0.55-2.76). The overall adjusted mortality rate ratio for isoniazid versus placebo was 1.18 (95% CI, 0.79-1.75). Stratifying by TST reactivity gave an adjusted mortality rate ratio in those who were TST-positive of 0.33 (95% CI, 0.09-1.23) and for TST-negative subjects, 1.39 (95% CI, 0.90-2.12).

CONCLUSIONS

Overall there was no statistically significant protective effect of daily isoniazid for 6 months in the prevention of tuberculosis. In the TST-positive subjects, where reactivation is likely to be the more important pathogenetic mechanism, there was some protection and some reduction in mortality, although this was not statistically significant. The small number of individuals in this subgroup made the power to detect a statistically significant difference in this subgroup low. Other influences that may have diluted the efficacy of isoniazid include a high rate of transmission of new infection and rapid progression to disease or insufficient duration of isoniazid in subjects with relatively advanced immunosuppression. The rate of drug resistance observed in subjects who received isoniazid and subsequently developed tuberculosis was low.

[Determination of acetylation phenotype in the therapeutic monitoring of drugs]

New methods for detecting the acetylation phenotype have been developed for therapeutic monitoring using isoniazid as the pharmacogenetic marker. The study is carried out with 4-chloro-5,7-dinitrobenzofurane by direct spectrophotometry, high performance liquid and thin-layer chromatography. The methods proved to be highly sensitive, selectively detecting isoniazid, simple, and requiring no sophisticated equipment. The methods were tried in examinations of patients with visceral diseases. Effects of various inductors on the acetylation rate were assessed.

High-performance liquid chromatographic determination of isoniazid, acetylisoniazid and hydrazine in biological fluids

The basic principle of derivatization of a hydrazide moiety with an aldehyde as applied in the method developed by Lacroix et al. [J. Chromatogr., 307 (1984) 137-144] for the quantitation of isoniazid and acetylisoniazid was improved by modification, standardization and extension to allow quantitation of hydrazine in patient samples. It could be shown that 40 microliters of 1% methanolic cinnamaldehyde per 200 microliters of deproteinized analysate gave maximal chromophoric isoniazid-cinnamaldehyde conjugate, read at 340 nm. The hydrolytic loss of isoniazid, crucial to the quantitation of acetylisoniazid, could be compensated for by introduction of an appropriate set of calibration curves. Although the method described here allows quantitation of monoacetylhydrazine and diacetylhydrazine, in addition to hydrazine, in mono-spiked samples, the method cannot be used for the quantitation of the acetylated metabolites of hydrazine in patient samples because of a lack of specificity. Linear calibration curves in the range 1-25 micrograms/ml for isoniazid and acetylisoniazid, 10-400 ng/ml for hydrazine and 50-1000 ng/ml for monoacetylhydrazine and diacetylhydrazine, could be constructed; analyte recoveries approaching 100% could be achieved in all instances.

N-acetyltransferase activity in the urine in Japanese subjects: comparison in healthy persons and bladder cancer patients

The activity of urinary N-acetylamino-transferase was determined by high-performance liquid chromatographic assay of acetylisoniazid and isoniazid after administration of isoniazid to healthy Japanese male and bladder cancer patients in Japan. The healthy subjects were 47 college students and 44 company employees ranging from 18 to 64 years old (mean +/- SC = 34.5 +/- 13.7). The bladder cancer group consisted of 58 male and 13 female patients, ranging from 28 to 82 years old (mean +/- SD = 60.8 +/- 11.6), who were being treated at several hospitals. The slow phenotype, defined as an acetylation ratio (acetylisoniazid/isoniazid) of less than 2.0, was observed in 13 (14.3%) of the 91 healthy subjects, and in 20 (28.2%) of the 71 bladder cancer patients; the difference between the two groups is significant (p < 0.05). A histogram of the acetylation ratio values showed an overall leftward shift of the patient group, indicating low values of acetylation ratio in this group as a whole (p < 0.01).

Maintenance of therapeutically active levels of isoniazid for prolonged periods in rabbits after a single implant of biodegradable polymer

SETTING

Poor patient compliance is the serious limiting factor in the chemotherapy of tuberculosis.

OBJECTIVE

To solve this problem we have been developing depot-drug delivery of antimycobacterial drugs. Earlier studies with mice using isoniazid in polylactic-co-glycolic acid (PLGA) co-polymer have shown that a single implant of the polymer could ensure sustained levels of free isoniazid for up to 8 weeks. Similar studies were not undertaken in rabbits.

DESIGN

The biodegradable PLGA polymer rods containing isoniazid were implanted on the back of the rabbits under anaesthesia in an isoniazid dose of 90 mg/kg. Concentrations of isoniazid and acetylisoniazid in serum and urine were determined by the high-performance liquid chromatography (HPLC) method at close intervals up to 96 h to study the burst-size, and later at weekly intervals up to 9 weeks to study the sustained levels.

RESULTS AND CONCLUSIONS

There was no abnormal release of isoniazid in the earlier periods. Concentrations of isoniazid > or = 0.2 microgram/ml were found both in serum and urine up to 63 days after implant. Urine specimen obtained at 6 weeks after giving the implant inhibited the growth of Mycobacterium tuberculosis in vitro as measured by the radiometric (Bactec) method. These findings in non-rodent animal species confirm the usefulness of the depot-drug delivery method of drug administration and warrant hopes for the successful treatment of tuberculosis avoiding the problem of non-compliance.

Pharmacokinetic evaluation of aconiazide, a potentially less toxic isoniazid prodrug

STUDY OBJECTIVE

To determine the bioavailability and renal elimination of isoniazid, acetylisoniazid, monoacetylhydrazine, diacetylhydrazine, aconiazide, and 2-formylphenoxyacetic acid.

STUDY DESIGN

Randomized, double-blind, two-period, crossover phase I study.

SETTING

Pharmacokinetics unit at a referral hospital that specializes in the treatment of mycobacterial infections.

SUBJECTS

Twelve healthy volunteers selected from the hospital staff.

INTERVENTIONS

Subjects received aconiazide tablets 650 mg (containing isoniazid 300 mg) and isoniazid tablets 300 mg. Blood and urine samples were collected over 24 hours after the dose.

MEASUREMENTS AND MAIN RESULTS

Intact aconiazide and 2-formylphenoxyacetic acid were not detected in the serum. Compared with isoniazid tablets, aconiazide's relative bioavailability (based on the area under the serum concentration-time curve) was 50.7%; its relative maximum serum concentration was 13.4%.

CONCLUSIONS

Isoniazid is less bioavailable after aconiazide tablets than after isoniazid tablets. The optimum dose of aconiazide remains to be determined.

Effects of isoniazid (INH) on the BCG-induced local immune response after intravesical BCG therapy for superficial bladder cancer

Because recent investigations showed that the use of isoniazid (INH) severely impaired the local immune reaction to intravesical bacillus Calmette-Guérin (BCG) in the bladder of guinea pigs, in this study the effect of INH in man has been investigated. Patients were treated with BCG with or without oral INH. The concentration of free INH in most urine samples of patients treated with BCG/INH was much higher (mean 38.0 +/- 60.9 micrograms INH/ml) than the minimal inhibitory concentration (MIC; 0.1 microgram INH/ml), suggesting at least a bacteriostatic potential of the INH present. However, in vitro studies showed that these urinary concentrations of INH did not kill BCG organisms effectively, even at a concentration of 150 micrograms/ml for 24 h. After the fifth and sixth BCG instillations a significant increase in the concentration of cytokines (IL2, IL6, IL8 and TNFa), IgG and IgA antibodies to BCG and the number of leukocytes in urine was observed. The leukocytes mainly consisted of granulocytes, besides monocytes/macrophages and, in lower amounts, T- and B-lymphocytes and natural killer (NK) cells. The absolute number of granulocytes and the concentration of IgG antibodies after BCG instillation were significantly suppressed by INH, whereas INH appeared to have no effect on the urinary cytokine and IgA antibody concentrations or the total number and phenotype of the leukocytes present. In conclusion, the results of this study indicate that INH does not impair the local immunological stimulation after BCG instillation in man as severely as was observed in the guinea pig and it may be expected that INH does not impair the antitumor efficacy of BCG.

Isoniazid and acetylisoniazid kinetics in serum and urine in pulmonary primary complex with intermittent regimen

Twenty patients, 1 through 13 years of age from Pediatric Tuberculosis Clinic of All India Institute of Medical Sciences, New Delhi, suffering from pulmonary primary complex (PPC) were investigated for serum and urine concentrations of isoniazid (INH) and acetylisoniazid (AcINH). Patients were put on an intermittent regimen - 2HR, 4H2R2, INH (H) was given in a dose of 10 mg/kg/day for first 2 months (the daily dose phase), followed by 20 mg/kg/dose in biweekly phase of regimen for rest of the 4 months, whereas, rifampicin (R) was given as 12 mg/kg in both daily as well as biweekly phases. In the biweekly phase of regimen, after 7 days of biweekly administration of drugs, INH and AcINH concentrations were estimated by HPLC at 0,1,3,5 and 7 hours in serum, and at 0-3, 3-6, 6-12 and 12-24 hour-intervals of drug administration in urine. Peak concentrations of INH and AcINH (Mean +/- SD) were 2.6 +/- 1.8 and 5.5 +/- 2.6 micrograms/ml in serum (Cmax), and 5.7 +/- 4.8 and 21.5 +/- 12.1 mg in urine, respectively. Time to achieve Cmax (Tmax), for INH and AcINH were 1 and 5 hours respectively while time of peak concentration in urine for INH was 3-6 hours and for AcINH 6-12 hours. The half-life (T1/2) of INH was 4.5 hours and area under serum-concentration time-curve (AUC0-7h) was 20.7 micrograms/ml/h (mean values). In biweekly phase (4H2R2) of regimen, just before administration of next dose, 0 hour (or 72 hours) concentration of INH was estimated at 0.47 +/- 0.3 micrograms/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental chemotherapy of tuberculosis using single dose treatment with isoniazid in biodegradable polymers

In previous studies we showed that a single implant of polylactic-co-glycolic acid (PLGA) polymer as a film containing isoniazid ensured sustained release of the drug for up to 4 weeks. These studies have been extended to PLGA polymer as a rod which is retrievable. Both types of implant gave therapeutically active levels of free isoniazid in liver and urine for prolonged periods. We assessed the in vivo chemotherapeutic efficacy of the rod implant against heavy infections of virulent Mycobacterium tuberculosis in C57Bl/6 mice. The chemotherapeutic data essentially confirmed the bioavailability data. In one chemotherapeutic study, one (7%) out of 15 mice which received the isoniazid polymer implant died within 30 days of bacterial challenge, while none of those receiving daily oral treatment died. In contrast, 14 (93%) of the 15 control mice died during the same period. In a second study similar results were obtained.

[Testing for heterogeneity in genetic polymorphism of N-acetylation using isoniazid by metameters--probit, logit, and arcsine transformation]

To investigate genetic polymorphism of N-acetylation in Japanese population we measured isoniazid (INH) and acetylisoniazid (AcINH) in the urine of 340 unrelated Japanese subjects. For the detection of polymorphism, we used probit analysis, logit analysis, and arcsine transformation of the logarithm of molar acetylation ratio (log (INH/AcINH)). The observed antimodes were -0.85 and -0.325 for the probit, 4.899 and 7.154 for the logit, 43.85 and 71.57 for the arcsine analysis plot. Probit and arcsine analysis were sensitive for the separation of intermediate from slow acetylators, while logit analysis was sensitive for the separation of rapid from intermediate acetylators. Clinically it is important to know to which genetic group the patient belongs because we may have to increase the dosage for the rapid acetylators to achieve the desired therapeutic effect, while we may have to reduce the dosage for slow acetylators in whom the incidence of side effect is high.

Molecular genotyping of N-acetylation polymorphism to predict phenotype

N-acetylation polymorphism is one of the representative pharmacogenetic traits that underlie interindividual and interethnic differences in response to xenobiotics. To develop a practical genotyping method to predict acetylator phenotype, we studied the conditions for accurate phenotyping, and identified the phenotype in 51 Japanese. Then we performed Southern blot analysis of genomic DNA from these subjects using 32P-labeled cDNA for polymorphic N-acetyltransferase in the liver, and found that four N-acetyltransferase alleles generated six genotypes. The present genotyping method predicted the rapid, intermediate, and slow acetylators correctly in 48 of 51 overall subjects (96%) and in all of 4 slow acetylators.

Controlled-release tablet formulation of isoniazid

Guar (GG) and Karaya gums (KG) alone and in combination with hydroxy-propylmethylcellulose (HPMC) were evaluated as release retarding materials to formulate a controlled-release tablet dosage form of isoniazid (1). In vitro release of 1 from tablets followed non-Fickian release profile with rapid initial release. Urinary excretion studies in normal subjects showed steady-state levels of 1 for 13 h. In vitro and in vivo data correlated (r = 0.9794). The studies suggested the potentiality of GG and KG as release retarding materials in formulating controlled-release tablet dosage forms of 1.

Fluorometric determination of isoniazid and its metabolites in urine by high-performance liquid chromatography using in-line derivatization

A rapid, simple, and accurate method has been developed for the determination of isoniazid and its metabolites (isonicotinic acid, isonicotinylglycine, and acetylisoniazid) in human urine by high-performance liquid chromatography. Isoniazid and its metabolites are separated by reversed-phase ion-exchange chromatography with a mobile phase containing hydrogen peroxide as a fluorogenic reagent and butanesulfonate as a hydrophobic ion exchanger, and are detected by fluorometry (excitation at 317 nm and emission at 415 nm) using in-line derivatization at high temperature (160 degrees C). The detection limits are isonicotinic acid, 0.5 mumol/L; isonicotinylglycine, 1 mumol/L; acetylisoniazid, 1 mumol/L; and isoniazid, 1.5 mumol/L. This method can be applied for acetylator phenotyping.

Sustained release of isoniazid in vivo from a single implant of a biodegradable polymer

In order to solve the problem of poor patient compliance, attempts were made to prolong the bioavailability of antimycobacterial drugs after a single administration. A single implant of polylactic-co-glycolic acid (PLGA) co-polymer containing isoniazid ensured its sustained release up to 6 weeks. The levels are comparable with those obtained from daily doses. Homogenates of liver and lungs from animals killed at 6 weeks after a single implant showed high antimycobacterial activity against Mycobacterium tuberculosis. Sera from the implant and daily dose group animals showed no significant difference in renal, hepatic and haematological parameters. The implant caused no local or systemic toxicity.