RESUMO
BACKGROUND: MDR-TB and XDR-TB have poor outcomes. OBJECTIVES: To examine the efficacy of tigecycline monotherapy in the hollow fibre system model of TB. METHODS: We performed pharmacokinetic/pharmacodynamic studies using tigecycline human-like concentration-time profiles in the hollow fibre system model of TB in five separate experiments using Mycobacterium tuberculosis in log-phase growth or as semi-dormant or intracellular bacilli, as monotherapy. We also compared efficacy with the isoniazid/rifampicin/pyrazinamide combination (standard therapy). We then applied extinction mathematics, morphisms and Latin hypercube sampling to identify duration of therapy with tigecycline monotherapy. RESULTS: The median tigecycline MIC for 30 M. tuberculosis clinical and laboratory isolates (67% MDR/XDR) was 2 mg/L. Tigecycline monotherapy was highly effective in killing M. tuberculosis in log-phase-growth and semi-dormant and intracellular M. tuberculosis. Once-a-week dosing had the same efficacy as daily therapy for the same cumulative dose; thus, tigecycline efficacy was linked to the AUC0-24/MIC ratio. Tigecycline replacement by daily minocycline after 4 weeks of therapy was effective in sterilizing bacilli. The AUC0-24/MIC ratio associated with optimal kill was 42.3. Tigecycline monotherapy had a maximum sterilizing effect (day 0 minus day 28) of 3.06â±â0.20 log10 cfu/mL (r2â=â0.92) compared with 3.92â±â0.45 log10 cfu/mL (r2â=â0.80) with optimized standard therapy. In our modelling, at a tigecycline monotherapy duration of 12 months, the proportion of patients with XDR-TB who reached bacterial population extinction was 64.51%. CONCLUSIONS: Tigecycline could cure patients with XDR-TB or MDR-TB who have failed recommended therapy. Once-a-week tigecycline could also replace second-line injectables in MDR-TB regimens.
Assuntos
Antituberculosos/administração & dosagem , Mycobacterium tuberculosis/efeitos dos fármacos , Tigeciclina/administração & dosagem , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Antituberculosos/farmacocinética , Esquema de Medicação , Monitoramento de Medicamentos , Quimioterapia Combinada , Humanos , Testes de Sensibilidade Microbiana , Modelos Teóricos , Método de Monte Carlo , Tigeciclina/farmacocinética , Distribuição TecidualRESUMO
Background: Ethionamide is used to treat multidrug-resistant tuberculosis (MDR-TB). The antimicrobial pharmacokinetics/pharmacodynamics, the contribution of ethionamide to the multidrug regimen, and events that lead to acquired drug resistance (ADR) are unclear. Methods: We performed a multidose hollow fiber system model of tuberculosis (HFS-TB) study to identify the 0-24 hour area under the concentration-time curve (AUC0-24) to minimum inhibitory concentration (MIC) ratios that achieved maximal kill and ADR suppression, defined as target exposures. Ethionamide-resistant isolates underwent whole-genome and targeted Sanger sequencing. We utilized Monte Carlo experiments (MCEs) to identify ethionamide doses that would achieve the target exposures in 10000 patients with pulmonary tuberculosis. We also identified predictors of time-to-sputum conversion in Tanzanian patients on ethionamide- and levofloxacin-based regimens using multivariate adaptive regression splines (MARS). Results: An AUC0-24/MIC >56.2 was identified as the target exposure in the HFS-TB. Early efflux pump induction to ethionamide monotherapy led to simultaneous ethambutol and isoniazid ADR, which abrogated microbial kill of an isoniazid-ethambutol-ethionamide regimen. Genome sequencing of isolates that arose during ethionamide monotherapy revealed mutations in both ethA and embA. In MCEs, 20 mg/kg/day achieved the AUC0-24/MIC >56.2 in >95% of patients, provided the Sensititre assay MIC was <2.5 mg/L. In the clinic, MARS revealed that ethionamide Sensititre MIC had linear negative relationships with time-to-sputum conversion until an MIC of 2.5 mg/L, above which patients with MDR-TB failed combination therapy. Conclusions: Ethionamide is an important contributor to MDR-TB treatment regimens, at Sensititre MIC <2.5 mg/L. Suboptimal ethionamide exposures led to efflux pump-mediated ADR.
Assuntos
Antituberculosos/farmacocinética , Etionamida/farmacocinética , Isoniazida/farmacocinética , Levofloxacino/farmacocinética , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Pulmonar/tratamento farmacológico , Antituberculosos/administração & dosagem , Etionamida/administração & dosagem , Humanos , Isoniazida/administração & dosagem , Levofloxacino/administração & dosagem , Método de Monte Carlo , Mutação , Escarro/microbiologiaRESUMO
Background: Gatifloxacin is used for the treatment of multidrug-resistant tuberculosis (MDR-TB). The optimal dose is unknown. Methods: We performed a 28-day gatifloxacin hollow-fiber system model of tuberculosis (HFS-TB) study in order to identify the target exposures associated with optimal kill rates and resistance suppression. Monte Carlo experiments (MCE) were used to identify the dose that would achieve the target exposure in 10000 adult patients with meningeal or pulmonary MDR-TB. The optimal doses identified were validated using probit analyses of clinical data from 2 prospective clinical trials of patients with pulmonary and meningeal tuberculosis. Classification and regression-tree (CART) analyses were used to identify the gatifloxacin minimum inhibitory concentration (MIC) below which patients failed or relapsed on combination therapy. Results: The target exposure associated with optimal microbial kill rates and resistance suppression in the HFS-TB was a 0-24 hour area under the concentration-time curve-to-MIC of 184. MCE identified an optimal gatifloxacin dose of 800 mg/day for pulmonary and 1200 mg/day for meningeal MDR-TB, and a clinical susceptibility breakpoint of MIC ≤ 0.5 mg/L. In clinical trials, CART identified that 79% patients failed therapy if MIC was >2 mg/L, but 98% were cured if MIC was ≤0.5 mg/L. Probit analysis of clinical data demonstrated a >90% probability of a cure in patients if treated with 800 mg/day for pulmonary tuberculosis and 1200 mg/day for meningeal tuberculosis. Doses ≤400 mg/day were suboptimal. Conclusions: Gatifloxacin doses of 800 mg/day and 1200 mg/day are recommended for pulmonary and meningeal MDR-TB treatment, respectively. Gatifloxacin has a susceptible dose-dependent zone at MICs 0.5-2 mg/L.
Assuntos
Antituberculosos/farmacocinética , Gatifloxacina/farmacocinética , Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose Meníngea/tratamento farmacológico , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Pulmonar/tratamento farmacológico , Humanos , Pulmão/microbiologia , Testes de Sensibilidade Microbiana , Método de Monte Carlo , Estudos Prospectivos , Tuberculose Meníngea/microbiologia , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Tuberculose Pulmonar/microbiologiaRESUMO
Background: Linezolid exhibits remarkable sterilizing effect in tuberculosis; however, a large proportion of patients develop serious adverse events. The congener tedizolid could have a better side-effect profile, but its sterilizing effect potential is unknown. Methods: We performed a 42-day tedizolid exposure-effect and dose-fractionation study in the hollow fiber system model of tuberculosis for sterilizing effect, using human-like intrapulmonary pharmacokinetics. Bacterial burden was examined using time to positivity (TTP) and colony-forming units (CFUs). Exposure-effect was examined using the inhibitory sigmoid maximal kill model. The exposure mediating 80% of maximal kill (EC80) was defined as the target exposure, and the lowest dose to achieve EC80 was identified in 10000-patient Monte Carlo experiments. The dose was also examined for probability of attaining concentrations associated with mitochondrial enzyme inhibition. Results: At maximal effect, tedizolid monotherapy totally eliminated 7.1 log10 CFU/mL Mycobacterium tuberculosis over 42 days; however, TTP still demonstrated some growth. Once-weekly tedizolid regimens killed as effectively as daily regimens, with an EC80 free drug 0- to 24-hour area under the concentration-time curve-to-minimum inhibitory concentration (MIC) ratio of 200. An oral tedizolid of 200 mg/day achieved the EC80 in 92% of 10000 patients. The susceptibility breakpoint was an MIC of 0.5 mg/L. The 200 mg/day dose did not achieve concentrations associated with mitochondrial enzyme inhibition. Conclusions: Tedizolid exhibits dramatic sterilizing effect and should be examined for pulmonary tuberculosis. A tedizolid dose of 200 mg/day or 700 mg twice a week is recommended for testing in patients; the intermittent tedizolid dosing schedule could be much safer than daily linezolid.
Assuntos
Antibacterianos/farmacocinética , Linezolida/farmacocinética , Mycobacterium tuberculosis/efeitos dos fármacos , Oxazolidinonas/farmacocinética , Tetrazóis/farmacocinética , Tuberculose Pulmonar/tratamento farmacológico , Antibacterianos/administração & dosagem , Humanos , Linezolida/administração & dosagem , Testes de Sensibilidade Microbiana , Método de Monte Carlo , Oxazolidinonas/administração & dosagem , Tetrazóis/administração & dosagemRESUMO
Background: Levofloxacin is used for the treatment of multidrug-resistant tuberculosis; however the optimal dose is unknown. Methods: We used the hollow fiber system model of tuberculosis (HFS-TB) to identify 0-24 hour area under the concentration-time curve (AUC0-24) to minimum inhibitory concentration (MIC) ratios associated with maximal microbial kill and suppression of acquired drug resistance (ADR) of Mycobacterium tuberculosis (Mtb). Levofloxacin-resistant isolates underwent whole-genome sequencing. Ten thousands patient Monte Carlo experiments (MCEs) were used to identify doses best able to achieve the HFS-TB-derived target exposures in cavitary tuberculosis and tuberculous meningitis. Next, we used an ensemble of artificial intelligence (AI) algorithms to identify the most important predictors of sputum conversion, ADR, and death in Tanzanian patients with pulmonary multidrug-resistant tuberculosis treated with a levofloxacin-containing regimen. We also performed probit regression to identify optimal levofloxacin doses in Vietnamese tuberculous meningitis patients. Results: In the HFS-TB, the AUC0-24/MIC associated with maximal Mtb kill was 146, while that associated with suppression of resistance was 360. The most common gyrA mutations in resistant Mtb were Asp94Gly, Asp94Asn, and Asp94Tyr. The minimum dose to achieve target exposures in MCEs was 1500 mg/day. AI algorithms identified an AUC0-24/MIC of 160 as predictive of microbiologic cure, followed by levofloxacin 2-hour peak concentration and body weight. Probit regression identified an optimal dose of 25 mg/kg as associated with >90% favorable response in adults with pulmonary tuberculosis. Conclusions: The levofloxacin dose of 25 mg/kg or 1500 mg/day was adequate for replacement of high-dose moxifloxacin in treatment of multidrug-resistant tuberculosis.
Assuntos
Antituberculosos/farmacocinética , Inteligência Artificial , Levofloxacino/farmacocinética , Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Pulmonar/tratamento farmacológico , Algoritmos , Antituberculosos/administração & dosagem , Farmacorresistência Bacteriana Múltipla , Quimioterapia Combinada , Humanos , Levofloxacino/administração & dosagem , Testes de Sensibilidade Microbiana , Método de Monte Carlo , Escarro/microbiologiaRESUMO
Linezolid has been successfully used for treatment of multidrug-resistant tuberculosis (MDR-TB). However, dose- and duration-related toxicity limit its use. Here, our aim was to search relevant pharmacokinetics (PK)/pharmacodynamics (PD) literature to identify the effective PK/PD index and to define the optimal daily dose and dosing frequency of linezolid in MDR-TB regimens. The systematic search resulted in 8 studies that met inclusion criteria. A significant PK variability was observed. Efficacy of linezolid seems to be driven by area under the concentration-time curve (AUC)/minimum inhibitory concentration (MIC). Literature is inconclusive about the preferred administration of a daily dose of 600 mg. To prevent development of drug resistance, an AUC/MIC ratio of 100 in the presence of a companion drug at relevant exposure is required. A daily dose of 600 mg seems appropriate to balance between efficacy and toxicity. Being a drug with a very narrow therapeutic window, linezolid treatment may benefit from a more personalized approach, that is, measuring actual MIC values and therapeutic drug monitoring.
Assuntos
Antituberculosos/farmacocinética , Linezolida/farmacocinética , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Antituberculosos/administração & dosagem , Monitoramento de Medicamentos , Humanos , Linezolida/administração & dosagem , Testes de Sensibilidade Microbiana , Método de Monte CarloRESUMO
The modern chemotherapy era started with Fleming's discovery of benzylpenicillin. He demonstrated that benzylpenicillin did not kill Mycobacterium tuberculosis In this study, we found that >64 mg/liter of static benzylpenicillin concentrations killed 1.16 to 1.43 log10 CFU/ml below starting inoculum of extracellular and intracellular M. tuberculosis over 7 days. When we added the ß-lactamase inhibitor avibactam, benzylpenicillin maximal kill (Emax) of extracellular log-phase-growth M. tuberculosis was 6.80 ± 0.45 log10 CFU/ml at a 50% effective concentration (EC50) of 15.11 ± 2.31 mg/liter, while for intracellular M. tuberculosis it was 2.42 ± 0.14 log10 CFU/ml at an EC50 of 6.70 ± 0.56 mg/liter. The median penicillin (plus avibactam) MIC against South African clinical M. tuberculosis strains (80% either multidrug or extensively drug resistant) was 2 mg/liter. We mimicked human-like benzylpenicillin and avibactam concentration-time profiles in the hollow-fiber model of tuberculosis (HFS-TB). The percent time above the MIC was linked to effect, with an optimal exposure of ≥65%. At optimal exposure in the HFS-TB, the bactericidal activity in log-phase-growth M. tuberculosis was 1.44 log10 CFU/ml/day, while 3.28 log10 CFU/ml of intracellular M. tuberculosis was killed over 3 weeks. In an 8-week HFS-TB study of nonreplicating persistent M. tuberculosis, penicillin-avibactam alone and the drug combination of isoniazid, rifampin, and pyrazinamide both killed >7.0 log10 CFU/ml. Monte Carlo simulations of 10,000 preterm infants with disseminated disease identified an optimal dose of 10,000 U/kg (of body weight)/h, while for pregnant women or nonpregnant adults with pulmonary tuberculosis the optimal dose was 25,000 U/kg/h, by continuous intravenous infusion. Penicillin-avibactam should be examined for effect in pregnant women and infants with drug-resistant tuberculosis, to replace injectable ototoxic and teratogenic second-line drugs.
Assuntos
Antituberculosos/uso terapêutico , Mycobacterium tuberculosis/efeitos dos fármacos , Penicilina G/uso terapêutico , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Adulto , Compostos Azabicíclicos/uso terapêutico , Linhagem Celular , Combinação de Medicamentos , Feminino , Humanos , Isoniazida/uso terapêutico , Testes de Sensibilidade Microbiana/métodos , Método de Monte Carlo , Gravidez , Pirazinamida/uso terapêutico , Rifampina/uso terapêuticoRESUMO
OBJECTIVES: To determine if tedizolid is effective for pulmonary Mycobacterium avium complex (MAC) disease, and to use pharmacokinetics/pharmacodynamics to design optimal doses. METHODS: We performed an exposure-response experiment in the hollow-fibre system model of intracellular MAC (HFS-MAC). We mimicked the tedizolid concentration-time profiles achieved in the lungs of patients treated once daily for 28 days. The HFS-MAC was sampled at intervals to determine the tedizolid pharmacokinetics and MAC intracellular burden. We identified the 0-24 h area under the concentration-time curves to MIC (AUC0-24/MIC) ratios associated with the following targets: 80% of maximal kill (EC80), bacteriostasis, and 1.0 and 2.0 log10 cfu/mL kill. We then performed 10â¯000 patient Monte Carlo simulations to identify the optimal dose for each of the exposure targets. RESULTS: Tedizolid achieved the feat of 2.0 log10 cfu/mL kill below initial bacterial burden, an effect not seen before in this model with other antibiotics. The tedizolid exposure associated with 1.0 log10 cfu/mL kill was a non-protein bound AUC0-24/MIC ratio of 23.46, while that associated with 2.0 log10 cfu/mL kill was 37.50, and the EC80 was 21.71. The clinical dose of 200 mg achieved each of these targets in â¼100% of the 10â¯000 patients, except the 2.0 log10 cfu/mL kill which required 300 mg/day. A tedizolid susceptibility MIC breakpoint of 1 mg/L is proposed. CONCLUSIONS: Tedizolid, at standard clinical doses, is expected to be bactericidal, and even achieved an unprecedented 2.0 log10 cfu/mL kill of MAC as monotherapy. We propose it as the backbone of short-course anti-MAC chemotherapy.
Assuntos
Antibacterianos/farmacologia , Pneumopatias/tratamento farmacológico , Complexo Mycobacterium avium/efeitos dos fármacos , Infecção por Mycobacterium avium-intracellulare/tratamento farmacológico , Organofosfatos/farmacologia , Oxazóis/farmacologia , Antibacterianos/farmacocinética , Antibacterianos/uso terapêutico , Área Sob a Curva , Humanos , Pneumopatias/microbiologia , Macrófagos/microbiologia , Testes de Sensibilidade Microbiana , Modelos Biológicos , Método de Monte Carlo , Organofosfatos/farmacocinética , Organofosfatos/uso terapêutico , Oxazóis/farmacocinética , Oxazóis/uso terapêutico , Células THP-1RESUMO
OBJECTIVES: To identify the pharmacokinetic/pharmacodynamic parameters and exposures of linezolid in the treatment of pulmonary Mycobacterium avium complex (MAC) disease. METHODS: Human-derived monocytes infected with MAC were inoculated into hollow-fibre systems for dose-effect and dose-scheduling studies. We mimicked linezolid concentration-time profiles achieved in adult human lungs treated for 28 days. Sampling to confirm that the intended linezolid pharmacokinetics had been achieved, and for enumeration of MAC colony-forming units, was performed based on repetitive sampling from each system over the 28 days. We then performed 10â¯000 patient Monte Carlo simulations to identify doses associated with optimal effect in the clinic. RESULTS: Linezolid achieved a hitherto unprecedented feat of at least 1.0 log10 cfu/mL reduction. Efficacy was most closely linked to the AUC0-24/MIC ratio. The AUC0-24/MIC ratio associated with no change in bacterial burden or bacteriostasis was 7.82, while that associated with 1.0 log10 cfu/mL kill was 42.06. The clinical dose of 600 mg/day achieved or exceeded the bacteriostasis exposure in 98.73% of patients. The proportion of 10â¯000 patients treated with the standard 1200 mg/day who achieved the exposure for 1.0 log10 cfu/mL kill was 70.64%, but was 90% for 1800 mg/day. The proposed MIC breakpoint for linezolid is 16 mg/L, with which 49%-80% of clinical isolates would be considered resistant. CONCLUSIONS: Linezolid is associated with a bactericidal effect in pulmonary MAC that is greater than that seen with other recommended drugs. However, because of the MIC distribution, doses that would optimize the bactericidal effect would be associated with a high adverse event rate.
Assuntos
Antibacterianos/farmacologia , Linezolida/farmacologia , Monócitos/microbiologia , Complexo Mycobacterium avium/efeitos dos fármacos , Infecção por Mycobacterium avium-intracellulare/tratamento farmacológico , Antibacterianos/administração & dosagem , Antibacterianos/farmacocinética , Área Sob a Curva , Relação Dose-Resposta a Droga , Humanos , Linezolida/administração & dosagem , Linezolida/farmacocinética , Testes de Sensibilidade Microbiana , Modelos Biológicos , Método de Monte Carlo , Células THP-1RESUMO
Carbapenems are now being explored for treatment of multidrug-resistant tuberculosis (MDR-TB), especially in conjunction with clavulanate. Clinical use is constrained by the need for multiple parenteral doses per day and the lack of knowledge of the optimal dose for sterilizing effect. Our objective was to identify the ertapenem exposure associated with optimal sterilizing effect and then design a once-a-day dose for clinical use. We utilized the hollow-fiber system model of tuberculosis in a 28-day exposure-response study of 8 different ertapenem doses in combination with clavulanate. The systems were sampled at predetermined time points to verify the concentration-time profile and identify the total bacterial burden. Inhibitory sigmoid maximum-effect (Emax) modeling was used to identify the relationship between total bacterial burden and the drug exposure and to identify optimal exposures. Contrary to the literature, ertapenem-clavulanate combination demonstrated good microbial kill and sterilizing effect. In a dose fractionation hollow-fiber study, efficacy was linked to percentage of the 24-h dosing interval of ertapenem concentration persisting above MIC (%TMIC). We performed 10,000 MDR-TB patient computer-aided clinical trial simulations, based on Monte Carlo methods, to identify the doses and schedule that would achieve or exceed a %TMIC of ≥40%. We identified an intravenous dosage of 2 g once per day as achieving the target in 96% of patients. An ertapenem susceptibility breakpoint MIC of 2 mg/liter was identified for that dose. An ertapenem dosage of 2 g once daily is the most suitable to be tested in a phase II study of sterilizing effect in MDR-TB patients.
Assuntos
Antituberculosos/farmacologia , Ácido Clavulânico/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , beta-Lactamas/farmacologia , Simulação por Computador , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Ertapenem , Humanos , Testes de Sensibilidade Microbiana , Método de Monte CarloRESUMO
Children with tuberculosis are treated with drug regimens copied from adults despite significant differences in antibiotic pharmacokinetics, pathology, and the microbial burden between childhood and adult tuberculosis. We sought to develop a new and effective oral treatment regimen specific to children of different ages. We investigated and validated the concept that target drug concentrations associated with therapy failure and death in children are different from those of adults. On that basis, we proposed a 4-step program to rapidly develop treatment regimens for children. First, target drug concentrations for optimal efficacy are derived from preclinical models of disseminated tuberculosis that recapitulate pediatric pharmacokinetics, starting with monotherapy. Second, 2-drug combinations were examined for zones of synergy, antagonism, and additivity based on a whole exposure-response surface. Exposures associated with additivity or synergy were then combined and the regimen was compared to standard therapy. Third, several exposures of the third drug were added, and a 3-drug regimen was identified based on kill slopes in comparison to standard therapy. Fourth, computer-aided clinical trial simulations are used to identify clinical doses that achieve these kill rates in children in different age groups. The proposed program led to the development of a 3-drug combination regimen for children from scratch, independent of adult regimens, in <2 years. The regimens and doses can be tested in animal models and in clinical trials.
Assuntos
Antituberculosos/administração & dosagem , Antituberculosos/farmacocinética , Simulação por Computador , Quimioterapia Combinada , Método de Monte Carlo , Tuberculose/tratamento farmacológico , Fatores Etários , Antituberculosos/efeitos adversos , Pré-Escolar , Monitoramento de Medicamentos , Quimioterapia Combinada/métodos , Quimioterapia Combinada/normas , Humanos , Lactente , Recém-Nascido , Testes de Sensibilidade Microbiana , Tuberculose/microbiologiaRESUMO
BACKGROUND: When treated with the same antibiotic dose, children achieve different 0- to 24-hour area under the concentration-time curves (AUC0-24) because of maturation and between-child physiological variability on drug clearance. Children are also infected by Mycobacterium tuberculosis isolates with different antibiotic minimum inhibitory concentrations (MICs). Thus, each child will achieve different AUC0-24/MIC ratios when treated with the same dose. METHODS: We used 10 000-subject Monte Carlo experiments to identify the oral doses of linezolid, moxifloxacin, and faropenem that would achieve optimal target exposures associated with optimal efficacy in children with disseminated tuberculosis. The linezolid and moxifloxacin exposure targets were AUC0-24/MIC ratios of 62 and 122, and a faropenem percentage of time above MIC >60%, in combination therapy. A linezolid AUC0-24 of 93.4 mg × hour/L was target for toxicity. Population pharmacokinetic parameters of each drug and between-child variability, as well as MIC distribution, were used, and the cumulative fraction of response (CFR) was calculated. We also considered drug penetration indices into meninges, bone, and peritoneum. RESULTS: The linezolid dose of 15 mg/kg in full-term neonates and infants aged up to 3 months and 10 mg/kg in toddlers, administered once daily, achieved CFR ≥ 90%, with <10% achieving linezolid AUC0-24 associated with toxicity. The moxifloxacin dose of 25 mg/kg/day achieved a CFR > 90% in infants, but the optimal dose was 20 mg/kg/day in older children. The faropenem medoxomil optimal dosage was 30 mg/kg 3-4 times daily. CONCLUSIONS: The regimen and doses of linezolid, moxifloxacin, and faropenem identified are proposed to be adequate for all disseminated tuberculosis syndromes, whether drug-resistant or -susceptible.
Assuntos
Antituberculosos/administração & dosagem , Fluoroquinolonas/administração & dosagem , Linezolida/administração & dosagem , Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose/tratamento farmacológico , Tuberculose/microbiologia , beta-Lactamas/administração & dosagem , Antituberculosos/farmacocinética , Área Sob a Curva , Criança , Pré-Escolar , Simulação por Computador , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Fluoroquinolonas/farmacocinética , Humanos , Lactente , Recém-Nascido , Linezolida/farmacocinética , Testes de Sensibilidade Microbiana , Modelos Estatísticos , Método de Monte Carlo , Moxifloxacina , beta-Lactamas/farmacocinéticaRESUMO
Current regimens used to treat pulmonary Mycobacterium abscessus disease have limited efficacy. There is an urgent need for new drugs and optimized combinations and doses. We performed hollow-fiber-system studies in which M. abscessus was exposed to moxifloxacin lung concentration-time profiles similar to human doses of between 0 and 800 mg/day. The minimum bactericidal concentration and MIC were 8 and 2 mg/liter, respectively, in our M. abscessus strain, suggesting bactericidal activity. Measurement of the moxifloxacin concentrations in each hollow-fiber system revealed an elimination rate constant (kel) of 0.11 ± 0.05 h(-1) (mean ± standard deviation) (half-life of 9.8 h). Inhibitory sigmoid maximal effect (Emax) modeling revealed that the highest Emax was 3.15 ± 1.84 log10 CFU/ml on day 3, and the exposure mediating 50% of Emax (EC50) was a 0- to 24-h area under the concentration time curve (AUC0-24)-to-MIC ratio of 41.99 ± 31.78 (r(2) = 0.99). The EC80 was an AUC0-24/MIC ratio of 102.11. However, no moxifloxacin concentration killed the bacteria to burdens below the starting inoculum. There was regrowth beyond day 3 in all doses, with replacement by a resistant subpopulation that had an MIC of >32 mg/liter by the end of the experiment. A quadratic function best described the relationship between the AUC0-24/MIC ratio and the moxifloxacin-resistant subpopulation. Monte Carlo simulations of 10,000 patients revealed that the 400- to 800-mg/day doses would achieve or exceed the EC80 in ≤12.5% of patients. The moxifloxacin susceptibility breakpoint was 0.25 mg/liter, which means that almost all M. abscessus clinical strains are moxifloxacin resistant by these criteria. While moxifloxacin's efficacy against M. abscessus was poor, formal combination therapy studies with moxifloxacin are still recommended.
Assuntos
Antibacterianos/farmacocinética , Fluoroquinolonas/farmacocinética , Modelos Estatísticos , Micobactérias não Tuberculosas/efeitos dos fármacos , Antibacterianos/farmacologia , Área Sob a Curva , Esquema de Medicação , Cálculos da Dosagem de Medicamento , Fluoroquinolonas/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Método de Monte Carlo , Moxifloxacina , Micobactérias não Tuberculosas/crescimento & desenvolvimento , Pneumonia/tratamento farmacológico , Pneumonia/microbiologiaRESUMO
Mycobacterium abscessus causes chronic pulmonary infections that are extremely difficult to cure. The currently recommended combination therapy is associated with high failure rates and relapse. Tigecycline has been explored in salvage regimens, with a response rate of 43% in those who received at least a month of therapy. We performed a dose-response study in a hollow-fiber system model of pulmonary M. abscessus infection in which we recapitulated tigecycline human pulmonary concentration-time profiles of 8 different doses for 21 days. We identified the maximal kill or efficacy in CFU per milliliter and the ratio of the 0- to 24-h area under the concentration-time curve to MIC (AUC/MIC) associated with 80% efficacy (EC80). The tigecycline efficacy was 5.38 ± 2.35 log10 CFU/ml, and the drug achieved the unprecedented feat of a bacterial level of 1.0 log10 CFU/ml below the pretreatment inoculum (1-log kill) of M. abscessus in the hollow-fiber system. The EC80 AUC/MIC ratio was 36.65, while that for a 1-log kill was 44.6. Monte Carlo experiments with 10,000 patients were used to identify the clinical dose best able to achieve the EC80 or 1-log kill. The standard dose of 100 mg/day had a cumulative fraction of response of 51% for the EC80 and 46% for 1-log kill. For both the EC80 target and 1-log kill, the optimal tigecycline clinical dose was identified as 200 mg/day. The susceptibility breakpoint was ≤0.5 mg/liter. Tigecycline is the most active single agent evaluated to date, and we propose that 200 mg/day be examined as the backbone of new combination therapy regimens to replace current treatment.
Assuntos
Antibacterianos/farmacologia , Pneumopatias/microbiologia , Minociclina/análogos & derivados , Mycobacterium/efeitos dos fármacos , Antibacterianos/farmacocinética , Área Sob a Curva , Humanos , Pneumopatias/metabolismo , Testes de Sensibilidade Microbiana , Minociclina/farmacocinética , Minociclina/farmacologia , Método de Monte Carlo , TigeciclinaRESUMO
The treatment of pulmonary Mycobacterium abscessus disease is associated with very high failure rates and easily acquired drug resistance. Amikacin is the key drug in treatment regimens, but the optimal doses are unknown. No good preclinical model exists to perform formal pharmacokinetics/pharmacodynamics experiments to determine these optimal doses. We developed a hollow-fiber system model of M. abscessus disease and studied amikacin exposure effects and dose scheduling. We mimicked amikacin human pulmonary pharmacokinetics. Both amikacin microbial kill and acquired drug resistance were linked to the peak concentration-to-MIC ratios; the peak/MIC ratio associated with 80% of maximal kill (EC80) was 3.20. However, on the day of the most extensive microbial kill, the bacillary burden did not fall below the starting inoculum. We performed Monte Carlo simulations of 10,000 patients with pulmonary M. abscessus infection and examined the probability that patients treated with one of 6 doses from 750 mg to 4,000 mg would achieve or exceed the EC80. We also examined these doses for the ability to achieve a cumulative area under the concentration-time curve of 82,232 mg · h/liter × days, which is associated with ototoxicity. The standard amikacin doses of 750 to 1,500 mg a day achieved the EC80 in ≤ 21% of the patients, while a dose of 4 g/day achieved this in 70% of the patients but at the cost of high rates of ototoxicity within a month or two. The susceptibility breakpoint was an MIC of 8 to 16 mg/liter. Thus, amikacin, as currently dosed, has limited efficacy against M. abscessus. It is urgent that different antibiotics be tested using our preclinical model and new regimens developed.
Assuntos
Amicacina/farmacocinética , Antibacterianos/farmacologia , Antibacterianos/farmacocinética , Testes de Sensibilidade Microbiana/métodos , Micobactérias não Tuberculosas/efeitos dos fármacos , Amicacina/farmacologia , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana/instrumentação , Modelos Biológicos , Método de Monte Carlo , Taxa de Mutação , Micobactérias não Tuberculosas/genética , Micobactérias não Tuberculosas/patogenicidadeRESUMO
BACKGROUND: It is believed that nonadherence is the proximate cause of multidrug-resistant tuberculosis (MDR-tuberculosis) emergence. The level of nonadherence associated with emergence of MDR-tuberculosis is unknown. Performance of a randomized controlled trial in which some patients are randomized to nonadherence would be unethical; therefore, other study designs should be utilized. METHODS: We performed hollow fiber studies for both bactericidal and sterilizing effect, with inoculum spiked with 0.5% rifampin- and isoniazid-resistant isogenic strains in some experiments. Standard therapy was administered daily for 28-56 days, with extents of nonadherence varying between 0% and 100%. Sizes of drug-resistant populations were compared using analysis of variance. We also explored the effect of pharmacokinetic variability on MDR-tuberculosis emergence using computer-aided clinical trial simulations of 10 000 Cape Town, South Africa, tuberculosis patients. RESULTS: Therapy failure was only encountered at extents of nonadherence ≥60%. Surprisingly, isoniazid- and rifampin-resistant populations did not achieve ≥1% proportion in any experiment and did not achieve a higher proportion with nonadherence. However, clinical trial simulations demonstrated that approximately 1% of tuberculosis patients with perfect adherence would still develop MDR-tuberculosis due to pharmacokinetic variability alone. CONCLUSIONS: These data, based on a preclinical model, demonstrate that nonadherence alone is not a sufficient condition for MDR-tuberculosis emergence.
Assuntos
Antituberculosos/administração & dosagem , Antituberculosos/farmacocinética , Simulação por Computador , Adesão à Medicação , Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Antituberculosos/farmacologia , Farmacorresistência Bacteriana Múltipla , Humanos , Isoniazida/administração & dosagem , Isoniazida/farmacologia , Modelos Biológicos , Método de Monte Carlo , Pirazinamida/administração & dosagem , Pirazinamida/farmacologia , Rifampina/administração & dosagem , Rifampina/farmacologiaRESUMO
It has become increasingly clear that anti-tuberculosis regimens need optimization. Information gained using pharmacokinetics/ pharmacodynamics (PK/PD) methods in hollow fiber and animal model studies, in conjunction with Monte Carlo simulations, can be used to achieve this goal. PK/PD models of anti-tuberculosis drugs in hollow fibers, mice and guinea pigs have been remarkably concordant. Using exposures derived in these models it has been shown that the standard doses of pyrazinamide, rifampin, and ethambutol should be increased for a better efficacy, while doses of isoniazid need to be individualized. In addition, PK/PD driven doses have been proposed for new anti-tuberculosis agents such as moxifloxacin and PA-824.
Assuntos
Antituberculosos/farmacologia , Modelos Biológicos , Tuberculose/tratamento farmacológico , Animais , Antituberculosos/administração & dosagem , Antituberculosos/farmacocinética , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Cobaias , Humanos , Camundongos , Método de Monte CarloRESUMO
Organisms of the Mycobacterium avium-intracellulare complex (MAC) have been demonstrated to be susceptible to moxifloxacin. However, clinical data on how to utilize moxifloxacin to treat disseminated MAC are scanty. In addition, there have been no moxifloxacin pharmacokinetic-pharmacodynamic (PK/PD) studies performed for MAC infection. We utilized an in vitro PK/PD model of intracellular MAC to study moxifloxacin PK/PD for disseminated disease. Moxifloxacin doses, based on a serum half-life of 12 h, were administered, and the 0- to 24-h area under the concentration-time curve (AUC(0-24)) to MIC ratios associated with 1.0 log(10) CFU/ml per week kill and 90% of maximal kill (EC(90)) were identified. The AUC(0-24)/MIC ratio associated with 1.0 log(10) CFU/ml kill was 17.12, and that with EC(90) was 391.56 (r(2) = 0.97). Next, the moxifloxacin MIC distribution in 102 clinical isolates of MAC was identified. The median MIC was 1 to 2 mg/liter. Monte Carlo simulations of 10,000 patients with disseminated MAC were performed to determine the probability that daily moxifloxacin doses of 400 and 800 mg/day would achieve or exceed 1.0 log(10) CFU/ml per week kill or EC(90). Doses of 400 and 800 mg/day achieved the AUC(0-24)/MIC ratio of 17.12 in 64% and 92% of patients, respectively. The critical concentration of moxifloxacin against MAC was identified as 0.25 mg/liter in Middlebrook media. The proposed susceptibility breakpoint means that a larger proportion of clinical isolates is resistant to moxifloxacin prior to therapy. For patients infected with susceptible isolates, however, 800 mg a day should be examined for safety and efficacy for disseminated M. avium disease.
Assuntos
Antibacterianos/farmacologia , Antibacterianos/farmacocinética , Compostos Aza/farmacologia , Compostos Aza/farmacocinética , Complexo Mycobacterium avium/efeitos dos fármacos , Infecção por Mycobacterium avium-intracellulare/tratamento farmacológico , Quinolinas/farmacologia , Quinolinas/farmacocinética , Antibacterianos/administração & dosagem , Área Sob a Curva , Compostos Aza/administração & dosagem , Linhagem Celular , Contagem de Colônia Microbiana , Fluoroquinolonas , Meia-Vida , Humanos , Técnicas In Vitro , Testes de Sensibilidade Microbiana , Modelos Biológicos , Método de Monte Carlo , Moxifloxacina , Infecção por Mycobacterium avium-intracellulare/metabolismo , Infecção por Mycobacterium avium-intracellulare/microbiologia , Ligação Proteica , Quinolinas/administração & dosagemRESUMO
Ethambutol, together with a macrolide, is the backbone for treatment of disseminated Mycobacterium avium disease. However, at the standard dose of 15 mg/kg of body weight/day, ethambutol efficacy is limited. In addition, susceptibility breakpoints have consistently failed to predict clinical outcome. We performed dose-effect studies with extracellular M. avium as well as with bacilli within human macrophages. The maximal kill rate (E(max)) for ethambutol against extracellular bacilli was 5.54 log(10) CFU/ml, compared to 0.67 log(10) CFU/ml for intracellular M. avium, after 7 days of exposure. Thus, extracellular assays demonstrated high efficacy. We created a hollow-fiber system model of intracellular M. avium and performed microbial pharmacokinetic-pharmacodynamic studies using pharmacokinetics similar to those of ethambutol for humans. The E(max) in the systems was 0.79 log(10) CFU/ml with 7 days of daily therapy, so the kill rates approximated those encountered in patients treated with ethambutol monotherapy. Ratio of peak concentration to MIC (C(max)/MIC) was linked to microbial kill rate. The C(max)/MIC ratio needed to achieve the 90% effective concentration (EC(90)) in serum was 1.23, with a calculated intramacrophage C(max)/MIC ratio of 13. In 10,000 patient Monte Carlo simulations, doses of 15, 50, and 75 mg/kg achieved the EC(90) in 35.50%, 76.81%, and 86.12% of patients, respectively. Therefore, ethambutol doses of >or=50 mg/kg twice a week would be predicted to be better than current doses of 15 mg/kg for treatment of disseminated M. avium disease. New susceptibility breakpoints and critical concentrations of 1 to 2 mg/liter were identified for the determination of ethambutol-resistant M. avium in Middlebrook broth. Given that the modal MIC of clinical isolates is around 2 mg/liter, most isolates should be considered ethambutol resistant.