Daniel Everitt

14-day bactericidal activity of PA-824, bedaquiline, pyrazinamide, and moxifloxacin combinations: a randomised trial

BACKGROUND New drugs, but also shorter, better-tolerated regimens are needed to tackle the high global burden of tuberculosis complicated by drug resistance and retroviral disease. We investigated new multiple-agent combinations over the first 14 days of treatment to assess their suitability for future development. METHODS In this prospective, randomised, early bactericidal activity (EBA) study, treatment-naive, drug-susceptible patients with uncomplicated pulmonary tuberculosis were admitted to hospitals in Cape Town, South Africa, between Oct 7, 2010, and Aug 19, 2011. Patients were randomised centrally by computer-generated randomisation sequence to receive bedaquiline, bedaquiline-pyrazinamide, PA-824-pyrazinamide, bedaquiline-PA-824, PA-824-moxifloxacin-pyrazinamide, or unmasked standard antituberculosis treatment as positive control. The primary outcome was the 14-day EBA assessed in a central laboratory from the daily fall in colony forming units (CFU) of M tuberculosis per mL of sputum in daily overnight sputum collections. Bilinear regression curves were fitted for each group separately and groups compared with ANOVA for ranks, followed by pair-wise comparisons adjusted for multiplicity. Clinical staff were partially masked but laboratory personnel were fully masked. This study is registered, NCT01215851. FINDINGS The mean 14-day EBA of PA-824-moxifloxacin-pyrazinamide (n=13; 0·233 [SD 0·128]) was significantly higher than that of bedaquiline (14; 0·061 [0·068]), bedaquiline-pyrazinamide (15; 0·131 [0·102]), bedaquiline-PA-824 (14; 0·114 [0·050]), but not PA-824-pyrazinamide (14; 0·154 [0·040]), and comparable with that of standard treatment (ten; 0·140 [0·094]). Treatments were well tolerated and appeared safe. One patient on PA-824-moxifloxacin-pyrazinamide was withdrawn because of corrected QT interval changes exceeding criteria prespecified in the protocol. INTERPRETATION PA-824-moxifloxacin-pyrazinamide is potentially suitable for treating drug-sensitive and multidrug-resistant tuberculosis. Multiagent EBA studies can contribute to reducing the time needed to develop new antituberculosis regimens. FUNDING The Global Alliance for TB Drug Development (TB Alliance).

Efficiency and safety of the combination of moxifloxacin, pretomanid (PA-824), and pyrazinamide during the first 8 weeks of antituberculosis treatment: a phase 2b, open-label, partly randomised trial in patients with drug-susceptible or drug-resistant pulmonary tuberculosis

BACKGROUND New antituberculosis regimens are urgently needed to shorten tuberculosis treatment. Following on from favourable assessment in a 2 week study, we investigated a novel regimen for efficacy and safety in drug-susceptible and multidrug-resistant (MDR) tuberculosis during the first 8 weeks of treatment. METHODS We did this phase 2b study of bactericidal activity--defined as the decrease in colony forming units (CFUs) of Mycobacterium tuberculosis in the sputum of patients with microscopy smear-positive pulmonary tuberculosis-at eight sites in South Africa and Tanzania. We enrolled treatment-naive patients with drug-susceptible, pulmonary tuberculosis, who were randomly assigned by computer-generated sequences to receive either 8 weeks of moxifloxacin, 100 mg pretomanid (formerly known as PA-824), and pyrazinamide (MPa100Z regimen); moxifloxacin, 200 mg pretomanid, and pyrazinamide (MPa200Z regimen); or the current standard care for drug-susceptible pulmonary tuberculosis, isoniazid, rifampicin, PZA, and ethambutol (HRZE regimen). A group of patients with MDR tuberculosis received MPa200Z (DRMPa200Z group). The primary outcome was bactericidal activity measured by the mean daily rate of reduction in M tuberculosis CFUs per mL overnight sputum collected once a week, with joint Bayesian non-linear mixed-effects regression modelling. We also assessed safety and tolerability by monitoring adverse events. This study is registered with ClinicalTrials.gov, number NCT01498419. FINDINGS Between March 24, 2012, and July 26, 2013 we enrolled 207 patients and randomly assigned them to treatment groups; we assigned 60 patients to the MPa100Z regimen, 62 to the MPa200Z regimen, and 59 to the HRZE regimen. We non-randomly assigned 26 patients with drug-resistant tuberculosis to the DRMPa200Z regimen. In patients with drug-susceptible tuberculosis, the bactericidal activity of MPa200Z (n=54) on days 0-56 (0·155, 95% Bayesian credibility interval 0·133-0·178) was significantly greater than for HRZE (n=54, 0·112, 0·093-0·131). DRMPa200Z (n=9) had bactericidal activity of 0·117 (0·070-0·174). The bactericidal activity on days 7-14 was strongly associated with bactericidal activity on days 7-56. Frequencies of adverse events were similar to standard treatment in all groups. The most common adverse event was hyperuricaemia in 59 (29%) patients (17 [28%] patients in MPa100Z group, 17 [27%] patients in MPa200Z group, 17 [29%] patients. in HRZE group, and 8 [31%] patients in DRMPa200Z group). Other common adverse events were nausea in (14 [23%] patients in MPa100Z group, 8 [13%] patients in MPa200Z group, 7 [12%] patients in HRZE group, and 8 [31%] patients in DRMPa200Z group) and vomiting (7 [12%] patients in MPa100Z group, 7 [11%] patients in MPa200Z group, 7 [12%] patients in HRZE group, and 4 [15%] patients in DRMPa200Z group). No on-treatment electrocardiogram occurrences of corrected QT interval more than 500 ms (an indicator of potential of ventricular tachyarrhythmia) were reported. No phenotypic resistance developed to any of the drugs in the regimen. INTERPRETATION The combination of moxifloxacin, pretomanid, and pyrazinamide, was safe, well tolerated, and showed superior bactericidal activity in drug-susceptible tuberculosis during 8 weeks of treatment. Results were consistent between drug-susceptible and MDR tuberculosis. This new regimen is ready to enter phase 3 trials in patients with drug-susceptible tuberculosis and MDR-tuberculosis, with the goal of shortening and simplifying treatment. FUNDING Global Alliance for TB Drug Development.

Urinary excretion of 6β-hydroxycortisol as an in vivo marker for CYP3A induction : Applications and recommendations

To evaluate the usefulness of 6β‐hydroxycortisol as a screen for CYP3A induction in early‐phase drug development.

Comparative Effects of Nabumetone, Sulindac, and Indomethacin on Urinary Prostaglandin Excretion and Platelet Function in Volunteers

Nonsteroidal antiinflammatory drugs differ with respect to their effects on prostaglandin metabolism in various tissues, a property that may be partly responsible for some of the differences in the pharmacologic activities and side‐effect profiles that are associated with their use. The effects of nabumetone on urinary prostaglandin excretion have not been reported. Fourteen healthy females, age 21–43 years, were treated with nabumetone (NAB) 1000 mg daily, sulindac (SUL) 200 mg every 12 hours, and indomethacin (IND) 50 mg every 12 hours for 7 days in a randomized period‐balanced crossover study. The effects of drug treatment on urinary prostaglandin excretion (PGE2, 6‐keto‐PGF1α, PGF2α, thromboxane [TX] B2) and platelet function (collagen‐induced whole blood platelet aggregation [CIPA] and template bleeding time) were determined on day 1 and day 7. For each treatment regimen, mean baseline urinary PG excretion values were comparable for each prostanoid, but the pattern of excretion differed in response to each drug. Treatment with NAB significantly increased the urinary excretion rates of PGE2 and PGF2α, but 6‐keto‐PGF1α and TXB2 excretion were unchanged. IND treatment did not result in a significant change in PGE2 excretion but did significantly reduce urinary 6‐keto‐PGF1α and TXB2 excretion rates. Reduced excretion of PGF2α was observed on both study days during treatment with IND and SUL. SUL treatment also resulted in increased urinary PGE2 excretion while significantly reducing 6‐keto‐PGF1α excretion on day 7. Significant differences were observed between the NAB and SUL regimens with respect to PGF2α excretion and between the NAB and SUL regimens for PGE2, PGF2α, 6‐keto‐PGFα1 (on day 1 only) and TXB2 (on day 1 only). Neither NAB nor SUL caused inhibition of CIPA or bleeding time although platelet aggregation was inhibited during IND treatment. That NAB treatment was neither associated with alterations in platelet function nor decreases in the urinary excretion of the vasodilatory prostaglandins, PGE2 and 6‐keto‐PGF1α, suggests that NAB possesses renal sparing properties.

Paroxetine does not affect the cardiac safety and pharmacokinetics of terfenadine in healthy adult men.

Potent CYP3A4 inhibitors such as ketoconazole can cause dangerous increases in plasma concentrations of the H-1 antagonist terfenadine. In light of recent reports that the selective serotonin reuptake inhibitor antidepressants may be weak CYP3A4 inhibitors, this study was designed to investigate the effects of paroxetine on the pharmacodynamic and pharmacokinetic profile of terfenadine. Twelve healthy male volunteers participated in a randomized open-label, two-period, steady-state crossover study. Terfenadine (60 mg twice daily for 8 days) was administered alone and with paroxetine at steady state (20 mg once daily for 15 days, with terfenadine on days 8 through 15). Extensive electrocardiogram monitoring was conducted throughout, and terfenadine and carboxyterfenadine pharmacokinetics were assessed at the end of each treatment period. One subject withdrew because of adverse experiences related to paroxetine, but the other 11 subjects completed the study uneventfully. On the final day of coadministration, the rate-corrected QT interval (QTc) was unaltered compared with terfenadine dosed alone; maximum QTc values (mean [SEM]) were 404 (4) and 405 (5) msec, respectively. Terfenadine pharmacokinetics were also unchanged; geometric mean steady-state area under the curve (AUC)tau values were 30.0 ng.hr/mL during coadministration compared with 30.8 ng.hr/mL when dosed alone (p > 0.05). The corresponding Cmax values were 3.68 and 3.64 ng/mL (p > 0.05). There was, however, a small (on average 17-20%), unexplained reduction in the steadystate Cmax and AUCtau of carboxyterfenadine during coadministration with paroxetine. In conclusion, paroxetine does not affect the pharmacokinetics or cardiovascular effects of terfenadine. The small reduction in carboxyterfenadine plasma concentrations is unlikely to be important clinically.

Effect of Intravenous Fenoldopam on Intraocular Pressure in Ocular Hypertension

Intravenous fenoldopam, a selective dopamine‐1 receptor agonist, was compared with placebo in this randomized, double‐blind, two‐period crossover study to evaluate its effects on intraocular pressure, aqueous dynamics, and macular blood flow in patients with elevated intraocular pressure or primary open‐angle glaucoma. Doses of fenoldopam were titrated up to a maximum of 0.5 μg/kg/min. Intraocular pressure, measured by pneumotonometry, was the primary outcome variable. Other outcomes included macular blood flow assessed by blue field examination, visual field examined by automated perimetry, aqueous outflow facility measured by tonography, and aqueous humor production determined by fluorophotometry. During infusions of fenoldopam, intraocular pressure increased from a mean baseline level of 29.2 mmHg to a mean maximum level of 35.7 mmHg. During the placebo infusions, pressure increased from a mean baseline of 28.4 mmHg to a mean of 29.0 mmHg at the time point that corresponded to the mean maximum intraocular pressure on the day intravenous fenoldopam was administered, to yield a mean difference in pressure between study days of 6.7 mmHg (P <0.05). There were no apparent changes in macular blood flow, visual fields, or production or outflow of aqueous humor associated with fenoldopam infusion. The increase in intraocular pressure seen in this population of patients with ocular hypertension during infusions of fenoldopam is consistent with fenoldopam‐associated increases in intraocular pressure reported in previous studies of healthy volunteers and of patients with accelerated systemic hypertension. These results further suggest that dopamine‐1 receptors play a role in the regulation of intraocular pressure.

Effect of a High-Calorie, High-Fat Meal on the Bioavailability and Pharmacokinetics of PA-824 in Healthy Adult Subjects

ABSTRACT PA-824 is a novel nitroimidazo-oxazine being developed as an antituberculosis agent. Two randomized studies evaluated the pharmacokinetics and safety of a single oral dose of PA-824 administered to healthy adult subjects 30 min after a high-calorie, high-fat meal (fed state) versus after a minimum 10-h fast (fasted state). A total of 48 subjects were dosed in the two studies in a randomized crossover design with PA-824 at dose levels of 50, 200, or 1,000 mg in the fed state or fasted state. After the administration of PA-824, the geometric mean ratios of Cmax and AUC0–∞ revealed an increase in exposure with the addition of a high-calorie, high-fat meal compared to the fasted state by 140 and 145% at 50 mg, 176 and 188% at 200 mg, and 450 and 473% at 50, 200, and 1,000 mg, respectively. The median Tmax in the fed state was 4 h for the 50-mg dose and 5 h for the 200- and 1,000-mg doses. In the fasted state, the median Tmax was 4 h for the 50- and 200-mg doses and 6.5 h for the 1,000-mg dose. All doses were well tolerated, and no serious adverse events occurred in either study. (This study has been registered at ClinicalTrials.gov under registration numbers NCT01828827 and NCT01830439.)

Evaluation of Pharmacokinetic Interaction between PA-824 and Midazolam in Healthy Adult Subjects

ABSTRACT This study assessed the safety, tolerability, and pharmacokinetic interaction between PA-824, a novel antitubercular nitroimidazo-oxazine, and midazolam, a CYP3A4 substrate, in 14 healthy adult male and female subjects. The study followed up on observations in vitro that PA-824 caused weak and time-dependent inhibition of CYP3A4. Subjects received a single oral dose of midazolam (2 mg), followed by a 2-day washout. After the washout, all subjects received PA-824 (400 mg) once daily for 14 consecutive days. On day 14, all subjects received the final PA-824 dose coadministered with a 2-mg oral dose of midazolam. The pharmacokinetic endpoints AUC0–t, AUC0–∞, and Cmax for midazolam and 1-hydroxy midazolam were compared between midazolam administered alone versus midazolam coadministered with PA-824. Statistical analysis demonstrated that the mean midazolam values of Cmax, AUC0–t, and AUC0–∞ parameters were reduced by ca. 16, 15, and 15%, respectively, when PA-824 was coadministered with midazolam. The total exposure (AUC) of 1-hydroxy midazolam was 13 to 14% greater when coadministered with PA-824 compared to midazolam administered alone. The Cmax of 1-hydroxy midazolam was similar between treatments. Based on these results, PA-824 does not inhibit or induce CYP3A4 to a clinically meaningful extent and is not likely to markedly affect the pharmacokinetics of CYP3A4 metabolized drugs.

Direct Susceptibility Testing of Mycobacterium tuberculosis for Pyrazinamide by Use of the Bactec MGIT 960 System

ABSTRACT Pyrazinamide (PZA) is a key antituberculosis drug, yet no rapid susceptibility test is commercially available. PZA drug susceptibility testing (DST) was performed directly on sputum samples from 327 patients and compared with the indirect method by using the Bactec MGIT 960 system in the context of patient screening for participation in a drug trial. Compared to standard indirect PZA DST, direct DST was successful in only 59% of cases, but results obtained were highly accurate and available faster. Agreement between the direct and indirect methods varied from 90 to 100% in each laboratory. The median times for obtaining PZA results from the time when the specimen was collected ranged from 11 to 16 days for the direct test and 18 to 95 days for the indirect test across laboratories. The direct method is accurate and reproducible across laboratories. It can be expected to accelerate results in >50% of cases, but it cannot replace indirect DST for PZA. Phenotypic methods remain the gold standard for DST in drug trials. If future studies can optimize the method to decrease the number of uninterpretable results, direct MGIT DST could be the new phenotypic DST standard for clinical trials, providing more rapid detection of resistance to new drugs in experimental regimens.

Safety, Pharmacokinetics and Antigenicity of Single and Repeat IM Injections of a Reshaped Human Monoclonal Antibody (RSHZ19) in Healthy Volunteers

Clinical Pharmacology & Therapeutics (1996) 59, 144–144; doi: 10.1038/sj.clpt.1996.76