Precision-Enhancing Risk Stratification Tools for Selecting Optimal Treatment Durations in Tuberculosis Clinical Trials.

Rationale: No evidence-based tools exist to enhance precision in the selection of patient-specific optimal treatment durations to study in tuberculosis clinical trials. Objectives: To develop risk stratification tools that assign patients with tuberculosis into risk groups of unfavorable outcome and inform selection of optimal treatment duration for each patient strata to study in clinical trials. Methods: Publicly available data from four phase 3 trials, each evaluating treatment duration shortening from 6 to 4 months, were used to develop parametric time-to-event models that describe unfavorable outcomes. Regimen, baseline, and on-treatment characteristics were evaluated as predictors of outcomes. Exact regression coefficients of predictors were used to assign risk groups and predict optimal treatment durations. Measurements and Main Results: The parametric model had an area under the receiver operating characteristic curve of 0.72. A six-item risk score (HIV status, smear grade, sex, cavitary disease status, body mass index, and Month 2 culture status) successfully grouped participants into low (1,060/3,791; 28%), moderate (1,740/3,791; 46%), and high (991/3,791; 26%) risk, requiring treatment durations of 4, 6, and greater than 6 months, respectively, to reach a target cure rate of 93% when receiving standard-dose rifamycin-containing regimens. With current one-duration-fits-all approaches, high-risk groups have a 3.7-fold (95% confidence interval, 2.7-5.1) and 2.4-fold (1.9-2.9) higher hazard risk of unfavorable outcomes compared with low- and moderate-risk groups, respectively. Four-month regimens were noninferior to the standard 6-month regimen in the low-risk group. Conclusions: Our model discrimination was modest but consistent with current models of unfavorable outcomes. Our results showed that stratified medicine approaches are feasible and may achieve high cure rates in all patients with tuberculosis. An interactive risk stratification tool is provided to facilitate decision-making in the regimen development pathway.

Quality assurance of rifampicin-containing fixed-drug combinations in South Africa: dosing implications.

SETTING: Rifampicin (RMP) drives treatment response in drug-susceptible tuberculosis. Low RMP concentrations increase the risk of poor outcomes, and drug quality needs to be excluded as a contributor to low RMP exposure. OBJECTIVES AND DESIGN: We performed an open-label, three-way cross-over study of three licensed RMP-containing formulations widely used in South Africa to evaluate the bioavailability of RMP in a two-drug fixed-dose combination tablet (2FDC) and a four-drug FDC (4FDC) against a single-drug reference. RMP dosed at 600 mg was administered 2 weeks apart in random sequence. Plasma RMP concentrations were measured pre-dose and 1, 2, 3, 4, 6, 8 and 12 h post-dose. The area under the concentration-time curve (AUC0-12) of the FDCs was compared to the single drug reference. Simulations were used to predict the impact of our findings. RESULTS: Twenty healthy volunteers (median age 22.8 years, body mass index 24.2 kg/m2) completed the study. The AUC0-12 of the 4FDC/reference (geometric mean ratio [GMR] 78%, 90%CI 69-89) indicated an average 20% reduction in RMP bioavailability in the 4FDC. The 2FDC/reference (GMR 104%, 90%CI 97-111) was bioequivalent. Simulations suggested dose adjustments to compensate for the poor bioavailability of RMP with the 4FDC, and revised weight-band doses to prevent systematic underdosing of low-weight patients. CONCLUSION: Post-marketing surveillance of in vivo bioavailability of RMP and improved weight band-based dosing are recommended.

Bioavailability of two licensed paediatric rifampicin suspensions: implications for quality control programmes.

SETTING: To assess the revised World Health Organization-recommended dose of 10-20 mg/kg rifampicin (RMP), we studied the steady state pharmacokinetics of RMP in South African children who received standard treatment for drug-susceptible tuberculosis (TB). OBJECTIVE: To determine the formulation effect on the pharmacokinetics of RMP. DESIGN: RMP plasma concentrations were characterised in 146 children (median age 1.4 years, range 0.2-10.2). The morning dose on the day of the pharmacokinetic evaluation was administered as one of two RMP single-drug oral suspensions. RESULTS: While one formulation achieved 2 h concentrations in the range of those observed in adults (median 6.54 mg/l, interquartile range [IQR] 4.47-8.84), the other attained a median bioavailability of only 25% of this, with a median 2 h concentration of 1.59 mg/l (IQR 0.89-2.38). CONCLUSION: RMP is a key drug for the treatment of TB. It is critical that the quality of RMP suspensions used to treat childhood TB is ensured.

Estimation of content of anti-TB drugs supplied at centres of the Revised National TB Control Programme in Tamil Nadu, India.

OBJECTIVE: To determine the content of certain antituberculosis (TB) drugs supplied at TB treatment centres of the Revised National TB Control Programme (RNTCP) in the state of Tamil Nadu, India. METHODS: Eight districts across the state were selected, and the following drugs were collected from five settings (District TB centre, TB unit, designated microscopy centres, DOT providers) in each district: rifampicin (150 and 450 mg), isoniazid (300 mg), pyrazinamide (500 and 750 mg), ethambutol (400 and 600 mg), ethionamide (250 mg), levofloxacin (500 mg) and cycloserine (250 mg). A maximum of 10 tablets/capsules were collected from each setting. The drugs were coded prior to analysis. All drugs were assayed by validated spectrophotometric methods. The acceptable limits for drug content were taken as 90-110% of the stated content. RESULTS: More than 90% of tablets of rifampicin 450 mg, isoniazid 300 mg, pyrazinamide 500 and 750 mg, ethambutol 400 and 600 mg and ethionamide 250 mg were within acceptable limits. Eighty per cent of rifampicin 150 mg, 21% of cycloserine 250 mg and 87% of levofloxacin 500 mg were within acceptable limits. The mean cycloserine content was below the acceptable limit in all districts, the mean drug content being 200 mg (range: 108-245 mg). CONCLUSION: This systematic study showed that the stated drug content of cycloserine was not reached in all districts. Deterioration of cycloserine could be minimised by storing the drug in refrigerators. The geographical location of the districts had no influence on the drug content.

Substandard and falsified anti-tuberculosis drugs: a preliminary field analysis.

SETTING: Pharmacies in 19 cities in Angola, Brazil, China, Democratic Republic of Congo, Egypt, Ethiopia, Ghana, India (n = 3), Kenya, Nigeria, Russia, Rwanda, Thailand, Turkey, Uganda, United Republic of Tanzania and Zambia. OBJECTIVE: To assess the quality of the two main first-line anti-tuberculosis medicines, isoniazid and rifampicin, procured from private-sector pharmacies, to determine if substandard and falsified medicines are available and if they potentially contribute to drug resistance in cities in low- and middle-income countries. DESIGN: Local nationals procured 713 treatment packs from a selection of pharmacies in 19 cities. These samples were tested for quality using 1) thin-layer chromatography to analyze levels of active pharmaceutical ingredient (API), and 2) disintegration testing. RESULTS: Of 713 samples tested, 9.1% failed basic quality testing for requisite levels of API or disintegration. The failure rate was 16.6% in Africa, 10.1% in India, and 3.9% in other middle-income countries. CONCLUSIONS: Substandard and falsified drugs are readily available in the private marketplace and probably contribute to anti-tuberculosis drug resistance in low- and middle-income countries. This issue warrants further investigation through large-scale studies of drug quality in all markets.

Simultaneous determination of efavirenz, rifampicin and its metabolite desacetyl rifampicin levels in human plasma.

A simple and rapid isocratic, high performance liquid chromatography (HPLC) assay employing solid phase extraction (SPE) for the simultaneous determination of the anti HIV drug, efavirenz, the anti-tuberculosis drug, rifampicin and the desacetyl metabolite of rifampicin in plasma from HIV/tuberculosis infected patients has been developed. Using a Zorbax SB-Phenyl reverse-phase analytical column with UV detection, good separation and detection of the drugs was attained within a 10min run time. Intra- and inter-assay precision RSD values were found to be less than 15% at the concentrations examined (0.1-20µg/mL). The LOQ was found to be 0.1µg/mL for each agent and the assay was found to generate a linear response up to 20µg/mL. This low cost assay can accurately detect efavirenz and rifampicin concentrations within a clinically relevant concentration range using standard chromatography equipment, making it particularly applicable to resource-limited settings.

The need for better data about counterfeit drugs in developing countries: a proposed standard research methodology tested in Chennai, India.

WHAT IS KNOWN AND OBJECTIVE: There is still surprisingly little basic research data to support widely repeated claims about the prevalence of drug counterfeiting. To meet the need for more reliable drug quality data, we designed a study framework that includes clear definitions of measured end points, sampling methods and assay technique. Our objective was to test this research design in Chennai (formerly Madras), India, using a joint Indian and Canadian team. METHODS: The city was divided into ten areas along municipal lines. From each area, ten stores and pharmacies selling drugs were selected. At each of these 100 outlets, three study drugs (artesunate, ciprofloxacin and rifampicin) were purchased. The 300 samples were tested by Liquid Chromatography-Mass Spectrometry. Assay content was expressed as a percentage of stated tablet content. Based on assay results and their distribution, we developed drug quality definitions for normal manufacturing standards, counterfeiting, decomposition, poor quality control and adulteration. RESULTS: The group mean for ciprofloxacin was close to normal manufacturing limits (99·2 ± 7·1%) but rifampicin (91·6 ± 5·7%), and artesunate (80·1 ± 9·1%), were both below normal pharmaceutical standards. Overall, 43% of all samples fell below the widely accepted manufacturing range of 90-110% of stated content. No tablet from any sample contained less than 50% of the stated dose. WHAT IS NEW AND CONCLUSION: The quality of at least some anti-infective drugs in Chennai is below commonly accepted standards but we found no evidence of criminal counterfeiting. Poor drug quality was most likely due to decomposition during storage or poor manufacturing standards. Our research methodology worked well under practical conditions and should hopefully be of value to others working in this area.

A training set selection strategy for a universal near-infrared quantitative model.

The purpose of this article is to propose an empirical solution to the problem of how many clusters of complex samples should be selected to construct the training set for a universal near infrared quantitative model based on the Naes method. The sample spectra were hierarchically classified into clusters by Ward's algorithm and Euclidean distance. If the sample spectra were classified into two clusters, the 1/50 of the largest Heterogeneity value in the cluster with larger variation was set as the threshold to determine the total number of clusters. One sample was then randomly selected from each cluster to construct the training set, and the number of samples in training set equaled the number of clusters. In this study, 98 batches of rifampicin capsules with API contents ranging from 50.1% to 99.4% were studied with this strategy. The root mean square errors of cross validation and prediction were 2.54% and 2.31% for the model for rifampicin capsules, respectively. Then, we evaluated this model in terms of outlier diagnostics, accuracy, precision, and robustness. We also used the strategy of training set sample selection to revalidate the models for cefradine capsules, roxithromycin tablets, and erythromycin ethylsuccinate tablets, and the results were satisfactory. In conclusion, all results showed that this training set sample selection strategy assisted in the quick and accurate construction of quantitative models using near-infrared spectroscopy.

Quality control of anti-tuberculosis FDC formulations in the global market: part II-accelerated stability studies.

OBJECTIVE: To determine the quality and performance of rifampicin (RMP) containing fixed-dose combination (FDC) formulations of anti-tuberculosis drugs sourced from the international market with respect to physical, chemical and dissolution properties after storage at accelerated stability conditions (40 degrees C/75% relative humidity) and to identify appropriate storage specifications. METHODS: Formulations across different companies and combinations were subjected to 6-month accelerated stability testing in packaging conditions recommended by the manufacturer. Various pharmacopeial and nonpharmacopeial tests for tablets were performed for 3- and 6-month samples. RESULTS: All the formulations were found to be stable, where extent of dissolution was within +/- 10% of that of the initial value, and all formulations passed the pharmacopeial limits for assay and content uniformity of 90-110% and +/- 15% of average drug content, respectively. CONCLUSIONS: Good quality RMP-containing FDCs that remain stable after 6-month accelerated stability testing are available in the marketplace.

Minimum sample size and sampling time requirements for assessment of rifampicin bioequivalence from FDC formulations.

SETTING: The WHO- and IUATLD-recommended protocol for rifampicin (RMP) bioequivalence utilises 20-22 volunteers and 8 h, whereas the requirement of other regulatory authorities is 12 volunteers with a 24 h sampling schedule. Differing sampling size and time requirements may change the outcome of RMP bioequivalence. OBJECTIVE: To determine the minimal sample size and time required to assess RMP bioequivalence from FDC formulations. DESIGN: Bioequivalence studies were conducted that fulfilled the criteria of the WHO and Indian regulatory protocols. From earlier studies, retrospective pharmacokinetic evaluation, power of the test and bioequivalence limits were also calculated using 8-22 volunteers and sampling points of 8-24 h. Pharmacokinetic and statistical evaluations from three representative studies showing low, moderate and high intra-subject variability are given to determine minimum requirements for RMP bioequivalence. RESULT: It was found that a sampling schedule up to 8 h was sufficient to compare the absorption process of RMP. There was no influence of reduced sample size on bioequivalence estimates of RMP that showed low or moderate variability. However, in a study showing higher variation, a sample size of 14-16 subjects was found to be optimal. CONCLUSION: It is possible to reduce the sample size requirement for determination of RMP bioequivalence using the WHO protocol.

Quality control of anti-tuberculosis fixed-dose combination formulations in the global market: an in vitro study.

OBJECTIVE: To determine the quality, and especially the dissolution properties of rifampicin, of fixed-dose combination (FDC) formulations of anti-tuberculosis agents manufactured by major market holders in the anti-tuberculosis sector and supplied for use in national tuberculosis control programmes. METHODS: Dissolution studies were performed for four formulations supplied by four different manufacturers in four dissolution media (0.1N and 0.01N HCl, phosphate buffer [PB] and 20% vegetable oil in PB), at four different agitation rates using USP apparatus II. The formulations were subjected to 4-week accelerated stability studies (40 degrees C / 75% RH) and evaluated for physical, chemical and dissolution stability. RESULTS: The formulations tested complied with pharmacopeial quality control (QC) tests. The extent of rifampicin release was independent of dissolution medium; however, a slight decrease in the dissolution rate was observed in two products. More than 75% of drug was released in 45 min at all agitation intensities except 30 rpm, and 20% oil in the medium reflected fed state. Formulations were stable in the packaging conditions recommended by the manufacturer for at least 4 weeks. CONCLUSIONS: The formulations tested passed the QC tests and were found to be stable. A decrease in the rate, although not the extent, of dissolution necessitated multiple point dissolution in gastric and intestinal pH conditions to ensure consistency in in vivo bioavailability.

A case series: initial outcome of persons with multidrug-resistant tuberculosis after treatment with the WHO standard retreatment regimen in Ho Chi Minh City, Vietnam.

Few data address the outcomes of patients who have multidrug-resistant tuberculosis (MDR-TB), defined as resistance to at least isoniazid and rifampin, and who receive a standard World Health Organization (WHO) recommended retreatment regimen after relapse or failure with initial treatment. In this case series, we examined treatment outcomes of a convenience sample of 42 relapse or failure patients who had documented MDR-TB and who had received a standard WHO retreatment regimen (2SHRZE/1HRZE/5H3R3E3). One patient died of tuberculosis in the last month of treatment; the remaining 41 patients completed retreatment. Of the 42, 14 (33%) were sputum smear-negative on completion of therapy. The proportion of patients cured of MDR-TB with the WHO retreatment regimen was similar to historic outcomes when no chemotherapy for TB was given.

Substandard tuberculosis drugs on the global market and their simple detection.

SETTING: The prevalence of substandard anti-tuberculosis drugs is unknown. To maximize the effectiveness of tuberculosis (TB) control efforts, simple, inexpensive drug quality screening methods are needed. DESIGN: Isoniazid (INH) and rifampin (RMP) single- and fixed-dose combination (FDC) formulations were collected from selected TB programs and pharmacies in Colombia, Estonia, India, Latvia, Russia and Vietnam. Samples were screened using a recently developed thin-layer chromatography (TLC) kit. All abnormal samples and a 40% random sample of normal formulations were further analyzed using confirmatory techniques. Samples outside of 85% to 115% of stated content, and/or containing compounds other than the stated drug, were defined as being substandard. RESULTS: Overall, 10% (4/40) of all samples, including 13% (4/30) RMP samples, contained <85% of stated content. More FDCs (5/24, 21%) than single-drug samples (2/16, 13%) were substandard. A comparison of TLC with the confirmatory analysis for RMP analysis showed a sensitivity of 100% (4/4), a specificity of 92% (24/26), a positive predictive value (PPV) of 67% (4/6), and a negative predictive value (NPV) of 100% (24/24). An analysis of INH showed a specificity of 90% (9/10). However, sensitivity, PPV, and NVP could not be determined. CONCLUSION: A substantial number of anti-tuberculosis drugs from several countries, in particular FDCs, were found to be substandard. Such drugs may contribute to the creation of drug-resistant TB. TLC is an effective, convenient, and inexpensive method for the detection of substandard drugs.

Synovectomy with rifampicine in haemophilic haemarthrosis.

The purpose of this paper was to assess the effectiveness of intra-articular injected rifampicine in haemophilic patients in order to achieve synovectomy by preventing repeated intra-articular bleeding. We have used this technique in haemophilic patients previously and reported our results on 13 cases [1]. Two hundred and fifty milligrams of rifampicine was injected into the elbow and ankle joints and 500 mg was injected into knee joints with 3-10 mL of lidocaine, depending on the joint size. The injections were repeated once a week for 7 weeks. Patients were only covered with antihaemophilic factor on the day of the injection at 30% above their coagulation level. We evaluated the results using two measures: subjective reports from the patient and objective assessment by the examiner. In the subjective reports the patient graded the results from their own perspective from 1 (poor) to 10 (excellent): 1-3, poor; 4-6, fair; 7-8, good; and 9-10, excellent. In the objective reports the grading was: excellent ('dry joint', full function, no haemarthrosis, no synovitis); good (clinical improvement, synovitis, reduction of haemarthroses, full function); fair synovitis (reduction of haemarthroses, no change in function); poor synovitis (persistent haemarthroses). This paper reports on the results of 38 patients with 39 joints with more that 3 years follow up, mean 1.8 years. There were 22 knees, nine elbows and eight ankles. Subjectively, there were excellent results in 21 joints (11 knees, six elbows and four ankles) good results in 15 joints (eight knees, three elbows and four ankles), fair results in two knees and a poor result in one knee. Objectively, results obtained were excellent in 20 joints (11 knees, six elbows and three ankles); good in 17 (nine knees, three elbows and five ankles); fair in one knee and poor in one knee.

Efficacy of single-dose ROM therapy plus low-dose convit vaccine as an adjuvant for treatment of paucibacillary leprosy patients with a single skin lesion.

The recent World Health Organization multicentric field study on the treatment of paucibacillary (PB) leprosy patients with single skin lesion (SSL) and a single dose of rifampin-ofloxacin-minocycline (ROM) brought new hope to those who are engaged in the eradication of leprosy from India. Being encouraged by the WHO report, we undertook the present hospital-based study and found that PB leprosy patients with SSL were morphologically and histopathologically heterogeneous. The histological spectrum of SSL ranged from indeterminate through tuberculoid (TT) to borderline tuberculoid (BT) leprosy, and most patients had active BT leprosy. Ninety new, untreated PB leprosy patients with SSL were included in the present study for comparative assessment of the efficacies of ROM and ROM plus Convit vaccine therapies. Children, pregnant women, lactating mothers and patients with any thickening of nerves were excluded. All patients were bacteriologically negative (skin-smear test) but lepromin reactive. The patients were divided into two groups after proper matching for morphological and histological status of SSL: a) The test group included 60 patients and the control group included 30 patients. The test group was given a single dose of ROM initially and two injections of low-dose Convit vaccine, one initially and the other at the end of 3 months. b) The control group was given only a single dose of ROM initially. Both groups were followed clinically every 2 weeks for 6 months and retested for histological, bacteriological and lepromin status at the end of 6 months. Thereafter, they were followed clinically every month for another 6 months. In the test group, the SSL resolved in 33.3%, regressed in 48.3%, and remained active in 18.3% of the patients, while the granuloma disappeared in 70% of the cases. Only one patient developed neuritis, and in another patient the disease relapsed on the eighth month. On the other hand, the SSL in the control patients resolved, regressed and remained active in 13.3%, 63.3% and 23.3% of the cases, respectively, while the granuloma disappeared in 53.3% of the cases. In the seven patients who remained active, the disease course was progressive, and two of them developed neuritis. The clinical outcome of the patients treated with ROM plus low-dose Convit vaccine was statistically superior to those treated with single-dose ROM therapy alone.

Evaluation of rifampicin bioequivalence in fixed-dose combinations using the WHO/IUATLD recommended protocol.

For an accurate assessment of rifampicin bioequivalence from fixed-dose combinations (FDCs), and to reduce the time and cost constraints associated with bioequivalence studies, the World Health Organization and the International Union Against Tuberculosis and Lung Disease have developed a simplified screening protocol. This study was undertaken with the objective of testing the applicability of this protocol for all types of FDCs. Data were obtained for volunteers common to three studies, and pharmacokinetic parameters were evaluated by different statistical tests. From the results, it has been demonstrated that the simplified screening protocol is suitable for evaluating the bioequivalence of rifampicin in all the types of FDCs available on the market.

Rifampin in drug-incorporated diet: effect of duration and temperature of storage. Relevance to drug-susceptibility testing in mice inoculated with M. leprae.

This paper is in two parts. Plasma concentrations of rifampin were assayed at 11 time points in 24 hr in mice fed one of three dosages of rifampin, either by gavage or by dietary incorporation. The drug-mixed diets had been stored for a maximum of 3 weeks at 4 degrees C or at room temperature (30 degrees C-35 degrees C). The peak concentration of rifampin produced by gavage was approximately 11/2 times higher than the maximum plasma concentration of the corresponding dosage in fresh diet. Plasma concentrations decreased with the increasing duration of storage of the drug-mixed diet, irrespective of whether the diet was stored at 4 degrees C or at room temperature. This decrease was less when the diet was stored at 4 degrees C than at room temperature. Drug levels were also assayed in another set of mice selected from ongoing drug-susceptibility experiments; these mice were fed a rifampin-incorporated diet stored at room temperature. The plasma concentrations in these mice, assayed at the time of foot pad harvest, were generally higher than in the 24-hr experiment. The harvest results from these mice were compared with the harvest results from a third set of mice, also from ongoing drug-susceptibility experiments, but fed a rifampin-mixed diet stored at 4 degrees C. Multiplication of Mycobacterium leprae in mouse foot pads was prevented by rifampin mixed in the diet at a dosage of greater than or equal to 0.003%, whether stored at room temperature or at 4 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)