Phase I Study Assessing the Pharmacokinetic Profile, Safety, and Tolerability of a Single Dose of Ceftazidime-Avibactam in Hospitalized Pediatric Patients

ABSTRACTThis study aimed to investigate the pharmacokinetics (PK), safety, and tolerability of a single dose of ceftazidime-avibactam in pediatric patients. A phase I, multicenter, open-label PK study was conducted in pediatric patients hospitalized with an infection and receiving systemic antibiotic therapy. Patients were enrolled into four age cohorts (cohort 1, ≥12 to <18 years; cohort 2, ≥6 to <12 years; cohort 3, ≥2 to <6 years; cohort 4, ≥3 months to <2 years). Patients received a single 2-h intravenous infusion of ceftazidime-avibactam (cohort 1, 2,000 to 500 mg; cohort 2, 2,000 to 500 mg [≥40 kg] or 50 to 12.5 mg/kg [<40 kg]; cohorts 3 and 4, 50 to 12.5 mg/kg). Blood samples were collected to describe individual PK characteristics for ceftazidime and avibactam. Population PK modeling was used to describe characteristics of ceftazidime and avibactam PK across all age groups. Safety and tolerability were assessed. Thirty-two patients received study drug. Mean plasma concentration-time curves, geometric mean maximum concentration (Cmax), and area under the concentration-time curve from time zero to infinity (AUC0–∞) were similar across all cohorts for both drugs. Six patients (18.8%) reported an adverse event, all mild or moderate in intensity. No deaths or serious adverse events occurred. The single-dose PK of ceftazidime and avibactam were comparable between each of the 4 age cohorts investigated and were broadly similar to those previously observed in adults. No new safety concerns were identified. (This study has been registered at ClinicalTrials.gov under registration no. NCT01893346.)

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Bioequivalence Study of Rivastigmine 6 mg Capsules (Single Dose) in Healthy Volunteers

American Journal of Alzheimer s Disease & Other Dementias® ◽

10.1177/1533317517712890 ◽

2017 ◽

Vol 32 (6) ◽

pp. 360-366

Author(s):

Dhiraj Abhyankar ◽

Ashish Shedage ◽

Milind Gole ◽

Preeti Raut

Keyword(s):

Single Dose ◽

Standard Deviation ◽

Geometric Mean ◽

Bioequivalence Study ◽

Open Label ◽

Time Curve ◽

Healthy Men ◽

Time Zero ◽

Concentration Time ◽

To Receive

Objective: To assess the bioequivalence of generic formulation of rivastigmine (test) and Exelon (reference). Methods: This randomized, open-label, 2-period, single-dose, 2-treatment, 2-sequence, crossover study was conducted in 40 healthy men under fed condition. Participants were randomized to receive a single dose of Exelon or rivastigmine capsule. Results: A total of 31 participants completed the study. Area under the concentration–time curve from time zero to time t (AUC0- t) and area under the concentration–time curve from time zero to infinity (AUC0-∞) for Exelon (mean [standard deviation], h·ng/mL) were 126.40 (56.95) and 129.46 (59.94), respectively, while they were 122.73 (43.46) and 125.08 (45.39) for rivastigmine. Geometric mean ratios of rivastigmine/Exelon were 99.17% for AUC0- t, 98.81% for AUC0-∞, and 105% for maximum observed plasma concentration ( Cmax). The 90% confidence intervals (CIs) were 94.14% to 104.46%, 93.77% to 104.12%, and 93.08% to 118.44%, respectively. Both formulations were well tolerated. Conclusion: The generic and reference formulations were bioequivalent, as the 90% CIs for Cmax, AUC0- t, and AUC0-∞ were within the range of 80% to 125%.

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Differential Effects of Tipranavir plus Ritonavir on Atorvastatin or Rosuvastatin Pharmacokinetics in Healthy Volunteers

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00449-09 ◽

2009 ◽

Vol 53 (10) ◽

pp. 4385-4392 ◽

Cited By ~ 40

Author(s):

P. A. Pham ◽

C. J. L. la Porte ◽

L. S. Lee ◽

R. van Heeswijk ◽

J. P. Sabo ◽

...

Keyword(s):

Single Dose ◽

Steady State ◽

Adverse Events ◽

Confidence Interval ◽

Geometric Mean ◽

Drug Reactions ◽

Open Label ◽

Time Curve ◽

Concentration Time ◽

Gastrointestinal Intolerance

ABSTRACT To identify pharmacokinetic (PK) drug-drug interactions between tipranavir-ritonavir (TPV/r) and rosuvastatin and atorvastatin, we conducted two prospective, open-label, single-arm, two-period studies. The geometric mean (GM) ratio was 1.37 (90% confidence interval [CI], 1.15 to 1.62) for the area under the concentration-time curve (AUC) for rosuvastatin and 2.23 (90% CI, 1.83 to 2.72) for the maximum concentration of drug in serum (C max) for rosuvastatin with TPV/r at steady state versus alone. The GM ratio was 9.36 (90% CI, 8.02 to 10.94) for the AUC of atorvastatin and 8.61 (90% CI, 7.25 to 10.21) for the C max of atorvastatin with TPV/r at steady state versus alone. Tipranavir PK parameters were not affected by single-dose rosuvastatin or atorvastatin. Mild gastrointestinal intolerance, headache, and mild reversible liver enzyme elevations (grade 1 and 2) were the most commonly reported adverse drug reactions. Based on these interactions, we recommend low initial doses of rosuvastatin (5 mg) and atorvastatin (10 mg), with careful clinical monitoring of rosuvastatin- or atorvastatin-related adverse events when combined with TPV/r.

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Pharmacokinetic Interactions between the Hormonal Emergency Contraception, Levonorgestrel (Plan B), and Efavirenz

Infectious Diseases in Obstetrics and Gynecology ◽

10.1155/2012/137192 ◽

2012 ◽

Vol 2012 ◽

pp. 1-4 ◽

Cited By ~ 45

Author(s):

Monica L. Carten ◽

Jennifer J. Kiser ◽

Awewura Kwara ◽

Samantha Mawhinney ◽

Susan Cu-Uvin

Keyword(s):

Geometric Mean ◽

Liver Function Tests ◽

Open Label ◽

Time Curve ◽

Geometric Means ◽

Concentration Time ◽

Plan B ◽

Effective Contraception ◽

Grade 3 ◽

Hiv Negative

Objectives. Compare the Plan B levonorgestrel (LNG) area under the concentration- time curve (AUC12) prior to and with efavirenz (EFV).Design. Prospective, open-label, single-arm, equivalence study.Methods. Healthy HIV-negative subjects underwent 12 hr intensive pharmacokinetic (PK) sampling following single dose LNG alone and after 14 days of EFV. Geometric means, Geometric Mean Ratios, and 90% confidence intervals (CI) are reported for PK Parameters.T-tests were utilized. Clinical parameters and liver function tests (LFTs) were assessed.Results. 24 women enrolled and 21 completed the study. With EFV, LNG AUC12was reduced 56% (95% CI: 49%, 62%) from 42.9 to 17.8 ng*hr/mL, and maximum concentration (Cmax⁡) was reduced 41% (95% CI: 33%, 50%) from 8.4 to 4.6 ng/mL. LNG was well tolerated with no grade 3 or 4 treatment-related toxicities.Conclusions. EFV significantly reduced LNG exposures. Higher LNG doses may be required with EFV. These results reinforce the importance of effective contraception in women taking EFV.

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Open-Label Crossover Study of Primaquine and Dihydroartemisinin-Piperaquine Pharmacokinetics in Healthy Adult Thai Subjects

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03704-14 ◽

2014 ◽

Vol 58 (12) ◽

pp. 7340-7346 ◽

Cited By ~ 32

Author(s):

Borimas Hanboonkunupakarn ◽

Elizabeth A. Ashley ◽

Podjanee Jittamala ◽

Joel Tarning ◽

Sasithon Pukrittayakamee ◽

...

Keyword(s):

Crossover Study ◽

Hospital Admissions ◽

Geometric Mean ◽

Radical Cure ◽

Open Label ◽

Time Curve ◽

Content Type ◽

Concentration Time ◽

Pharmacokinetic Assessment ◽

Adult Volunteers

ABSTRACTDihydroartemisinin-piperaquine is an artemisinin-based combination treatment (ACT) recommended by the WHO for uncomplicatedPlasmodium falciparummalaria, and it is being used increasingly for resistant vivax malaria where combination with primaquine is required for radical cure. The WHO recently reinforced its recommendations to add a single dose of primaquine to ACTs to reduceP. falciparumtransmission in low-transmission settings. The pharmacokinetics of primaquine and dihydroartemisinin-piperaquine were evaluated in 16 healthy Thai adult volunteers in a randomized crossover study. Volunteers were randomized to two groups of three sequential hospital admissions to receive 30 mg (base) primaquine, 3 tablets of dihydroartemisinin-piperaquine (120/960 mg), and the drugs together at the same doses. Blood sampling was performed over 3 days following primaquine and 36 days following dihydroartemisinin-piperaquine dosing. Pharmacokinetic assessment was done with a noncompartmental approach. The drugs were well tolerated. There were no statistically significant differences in dihydroartemisinin and piperaquine pharmacokinetics with or without primaquine. Dihydroartemisinin-piperaquine coadministration significantly increased plasma primaquine levels; geometric mean ratios (90% confidence interval [CI]) of primaquine combined versus primaquine alone for maximum concentration (Cmax), area under the concentration-time curve from 0 h to the end of the study (AUC0–last), and area under the concentration-time curve from 0 h to infinity (AUC0–∞) were 148% (117 to 187%), 129% (103 to 163%), and 128% (102 to 161%), respectively. This interaction is similar to that described recently with chloroquine and may result in an enhanced radical curative effect. (This study has been registered at ClinicalTrials.gov under registration no. NCT01525511.)

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Pharmacokinetics of Telbivudine in Healthy Subjects and Absence of Drug Interaction with Lamivudine or Adefovir Dipivoxil

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01313-05 ◽

2006 ◽

Vol 50 (7) ◽

pp. 2309-2315 ◽

Cited By ~ 31

Author(s):

Xiao-Jian Zhou ◽

Barbara A. Fielman ◽

Deborah M. Lloyd ◽

George C. Chao ◽

Nathaniel A. Brown

Keyword(s):

Single Dose ◽

Steady State ◽

Plasma Concentration ◽

Healthy Subjects ◽

Adefovir Dipivoxil ◽

Geometric Mean ◽

Time Curve ◽

Concentration Time ◽

Plasma Pharmacokinetics ◽

Plasma Concentration Time Curve

ABSTRACT Two phase I studies were conducted to assess the plasma pharmacokinetics of telbivudine and potential drug-drug interactions between telbivudine (200 or 600 mg/day) and lamivudine (100 mg/day) or adefovir dipivoxil (10 mg/day) in healthy subjects. Study drugs were administered orally. The pharmacokinetics of telbivudine were characterized by rapid absorption with biphasic disposition. The maximum concentrations in plasma (C max) were reached at median times ranging from 2.5 to 3.0 h after dosing. Mean single-dose C max and area under the plasma concentration-time curve from time zero to infinity (AUC0-∞) were 1.1 and 2.9 μg/ml and 7.4 and 21.8 μg · h/ml for the 200- and 600-mg telbivudine doses, respectively. Steady state was reached after daily dosing for 5 to 7 days. The mean steady-state C max and area under the plasma concentration-time curve over the dosing interval (AUCτ) were 1.2 and 3.4 μg/ml and 8.9 and 27.5 μg · h/ml for the 200- and 600-mg telbivudine repeat doses, respectively. The steady-state AUCτ of telbivudine was 23 to 57% higher than the single-dose values. Concomitant lamivudine or adefovir dipivoxil did not appear to significantly alter the steady-state plasma pharmacokinetics of telbivudine; the geometric mean ratios and associated 90% confidence interval (CI) for the AUCτ of telbivudine alone versus in combination were 106.3% (92.0 to 122.8%) and 98.6% (86.4 to 112.5%) when coadministered with lamivudine and adefovir dipivoxil, respectively. Similarly, the steady-state plasma pharmacokinetics of lamivudine or adefovir were not markedly affected by the coadministration of telbivudine; the geometric mean ratios and associated 90% CI, alone versus in combination with telbivudine, were 99.0% (87.1 to 112.4%) and 92.2% (84.0 to 101.1%), respectively, for the lamivudine and adefovir AUCτ values. Moreover, the combination regimens studied were well tolerated in all subjects. The results from these studies provide pharmacologic support for combination therapy or therapy switching involving telbivudine, lamivudine, and adefovir dipivoxil for the treatment of chronic hepatitis B virus infection.

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1159. Pharmacokinetics, Safety, and Tolerability of Imipenem/Cilastatin/Relebactam in Pediatric Participants With Confirmed or Suspected Gram-negative Bacterial Infections: A Phase 1b, Open-label, Single-Dose Clinical Trial

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab466.1352 ◽

2021 ◽

Vol 8 (Supplement_1) ◽

pp. S671-S671

Author(s):

John S Bradley ◽

Nataliia Makieieva ◽

Camilla Tøndel ◽

Emmanuel Roilides ◽

Matthew S Kelly ◽

...

Keyword(s):

Single Dose ◽

Plasma Concentration ◽

Bacterial Infections ◽

Geometric Mean ◽

Complicated Urinary Tract Infection ◽

Research Support ◽

Open Label ◽

Gram Negative ◽

Age Cohorts ◽

The Mean

Abstract Background Imipenem/cilastatin/relebactam (IMI/REL) is approved for treating hospital-acquired/ventilator-associated bacterial pneumonia, complicated urinary tract infection, and complicated intra-abdominal infection in adults. This study assessed single-dose pharmacokinetics (PK), safety, and tolerability of IMI/REL in neonatal and pediatric participants with confirmed or suspected gram-negative bacterial infections. Methods This was a phase 1, open-label, non-comparative study (NCT03230916). Age- and weight-adjusted dosing is summarized in Table 1. The primary objective was to characterize the PK profiles for imipenem and relebactam after a single intravenous dose of IMI/REL. PK parameters were analyzed using population modeling. The PK target for imipenem was the percent time of the dosing interval that the unbound plasma concentration exceeded the minimum inhibitory concentration (%fT >MIC) of ≥30% (MIC used, 2 µg/mL). The PK target for relebactam was an area under the curve (AUC)/MIC ratio >8 (MIC used, 2 µg/mL), corresponding to AUC0-24h >58.88 μM∙h. Safety and tolerability were assessed for up to 14 days after drug infusion. Results Of the 46 participants who received IMI/REL, 42 were included in the PK analysis. The mean plasma concentration-time profiles for imipenem and relebactam were generally comparable across age cohorts (Figure). For imipenem, the geometric mean %ƒT >MIC ranged from 50% to 94% and the mean maximum concentration (Cmax) ranged from 65 μM to 126 μM (Table 2). For relebactam, the geometric Cmax ranged from 33 μM to 87 μM and mean AUC0-6h ranged from 51 μM·h to 159 μM·h across the age cohorts (Table 2). IMI/REL was well tolerated with 8 (17.4%) participants experiencing ≥1 adverse events (AE) and 2 (4.3%) participants experiencing AE that were deemed drug related by the investigator. Drug-related AE were increased alanine aminotransferase, increased aspartate aminotransferase, anemia, and diarrhea, which were non-serious, mild in severity, and resolved within the follow-up period of 14 days. Figure 1 Conclusion Imipenem and relebactam exceeded the pediatric plasma PK targets across pediatric age cohorts in the study; the single doses of IMI/REL were well tolerated. These results will inform IMI/REL dose selection for further pediatric clinical evaluation. Disclosures Camilla Tøndel, MD, PhD, Merck & Co., Inc., (Grant/Research Support) Emmanuel Roilides, MD, PhD, FIDSA, FAAM, FESCMID, FECMM, FISAC, Merck Sharp & Dohme Corp. (Consultant, Grant/Research Support) Matthew S. Kelly, MD, MPH, Merck Sharp & Dohme Corp. (Consultant, Grant/Research Support) Munjal Patel, PhD, Merck Sharp & Dohme Corp. (Employee, Shareholder) Pavan Vaddady, PhD, Merck Sharp & Dohme Corp. (Employee) Alok Maniar, MD, MPH, Merck Sharp & Dohme Corp. (Employee, Shareholder) Ying Zhang, PhD, Merck & Co., Inc. (Employee, Shareholder) Amanda Paschke, MD MSCE, Merck Sharp & Dohme Corp. (Employee, Shareholder) Joan R. Butterton, MD, Merck Sharp & Dohme Corp. (Employee, Shareholder) Luke F. Chen, MBBS MPH MBA FRACP FSHEA FIDSA, Merck (Employee)

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CTNI-09. A PHASE I HEALTHY VOLUNTEER STUDY ON THE RELATIVE BIOAVAILABILITY AND FOOD EFFECT OF CAPSULE AND GRANULE FORMULATIONS OF SELUMETINIB

Neuro-Oncology ◽

10.1093/neuonc/noaa215.176 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii43-ii43

Author(s):

Sarit Cohen-Rabbie ◽

Alexandra Mattinson ◽

Karen So ◽

Nan Wang ◽

Eileen McBride ◽

...

Keyword(s):

Phase I ◽

Pediatric Patients ◽

Food Effect ◽

Geometric Mean ◽

Open Label ◽

Capsule Formulation ◽

Dry Eyes ◽

Fasted State ◽

Volunteer Study ◽

Granule Formulation

Abstract Selumetinib (AZD6244, ARRY-142886) is an oral, potent and highly selective allosteric MEK 1/2 inhibitor approved by the FDA as a capsule formulation for treatment of pediatric patients ≥ 2 years old with neurofibromatosis type 1 and symptomatic, inoperable plexiform neurofibromas. A new granule formulation is being developed to support dose flexibility and for patients unable to swallow capsules. This Phase I, open-label, single-center, randomized crossover pharmacokinetics study (NCT03649165) investigated the new granule versus capsule formulation in both fasted and fed (low-fat) states. Twenty-four healthy adult male volunteers were randomized to receive single-dose selumetinib in one of four treatment sequences: 25 mg granule (fasted); 50 mg capsule (fasted); 25 mg granule (fed); and 50 mg capsule (fed). Primary endpoint: to compare pharmacokinetics of the formulations in fasted state. Secondary endpoints: pharmacokinetics of the formulations in fasted versus fed states, granule palatability, safety and tolerability. In fasted state, a slight delay in absorption of selumetinib by ~0.60 h, with geometric mean ratios (90% CI) of 0.65 (0.58, 0.74) for Cmax/dose and 0.87 (0.81, 0.92) for AUC/dose, was detected when administered as granule versus capsule. For granule in fed versus fasted states, geometric mean Cmax and AUC ratios (90% CI) were 0.61 (0.51, 0.72) and 0.97 (0.91, 1.02). For capsule in fed versus fasted states, geometric mean Cmax and AUC ratios (90% CI) were 0.40 (0.33, 0.48) and 0.62 (0.55, 0.70). Granule palatability was acceptable; volunteers indicated they would take it again. Selumetinib was well-tolerated; for both formulations, few adverse events of mild intensity were reported; dry eyes (fasted) versus dry eyes and rhinorrhea (fed) were most frequent. This was the first study to test the granule formulation in humans; results indicate the granule formulation has similar AUC to the capsule formulation and minimal food effect, supporting planned clinical trials in pediatric patients.

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Atogepant and sumatriptan: no clinically relevant drug–drug interactions in a randomized, open-label, crossover trial

Pain Management ◽

10.2217/pmt-2021-0073 ◽

2021 ◽

Author(s):

Ramesh Boinpally ◽

Abhijeet Jakate ◽

Matthew Butler ◽

Antonia Periclou

Keyword(s):

Plasma Concentration ◽

Crossover Trial ◽

Peak Plasma ◽

Peak Plasma Concentration ◽

Geometric Mean ◽

Open Label ◽

Time Curve ◽

Concentration Time ◽

Pharmacokinetic Interactions ◽

Randomized Crossover Study

Aim: To evaluate pharmacokinetic interactions of atogepant with sumatriptan, an open-label, randomized, crossover study was conducted. Patients & methods: Thirty healthy adults received atogepant 60 mg, sumatriptan 100 mg, or coadministered drugs. Primary end point was geometric mean ratios (GMRs) and 90% CIs of interventions for area under the plasma concentration–time curve from time 0 to t (AUC0-t) or infinity (AUC0-∞) and peak plasma concentration (Cmax). Results: Atogepant GMRs for AUC0-t and AUC0-∞ versus with sumatriptan were within 90% CI 0.80–1.25, indicating no interaction; atogepant Cmax was reduced by 22% (GMR: 0.78; 90% CI: 0.69–0.89) with sumatriptan. Sumatriptan GMRs for AUC0-t, AUC0-∞ and Cmax versus with atogepant were within 90% CI 0.80–1.25. Conclusion: Atogepant with sumatriptan had no clinically relevant pharmacokinetic interactions.

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Evaluation of the Pharmacokinetic Interaction between Repeated Doses of Rifapentine or Rifampin and a Single Dose of Bedaquiline in Healthy Adult Subjects

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04171-14 ◽

2014 ◽

Vol 59 (2) ◽

pp. 1219-1224 ◽

Cited By ~ 17

Author(s):

Helen Winter ◽

Erica Egizi ◽

Stephen Murray ◽

Ngozi Erondu ◽

Ann Ginsberg ◽

...

Keyword(s):

Single Dose ◽

Healthy Adult ◽

Geometric Mean ◽

Pharmacokinetic Interaction ◽

Time Curve ◽

Concentration Time ◽

Period 2 ◽

Repeated Doses ◽

Single Sequence ◽

Time Point

ABSTRACTThis study assessed the effects of rifapentine or rifampin on the pharmacokinetics of a single dose of bedaquiline and its M2 metabolite in healthy subjects using a two-period single-sequence design. In period 1, subjects received a single dose of bedaquiline (400 mg), followed by a 28-day washout. In period 2, subjects received either rifapentine (600 mg) or rifampin (600 mg) from day 20 to day 41, as well as a single bedaquiline dose (400 mg) on day 29. The pharmacokinetic profiles of bedaquiline and M2 were compared over 336 h after the administration of bedaquiline alone and in combination with steady-state rifapentine or rifampin. Coadministration of bedaquiline with rifapentine or rifampin resulted in lower bedaquiline exposures. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for the maximum observed concentration (Cmax), area under the concentration-time curve to the last available concentration time point (AUC0–t), and AUC extrapolated to infinity (AUC0–inf) of bedaquiline were 62.19% (53.37 to 72.47), 42.79% (37.77 to 48.49), and 44.52% (40.12 to 49.39), respectively, when coadministered with rifapentine. Similarly, the GMRs and 90% CIs for theCmax, AUC0–t, and AUC0–infof bedaquiline were 60.24% (51.96 to 69.84), 41.36% (37.70 to 45.36), and 47.32% (41.49 to 53.97), respectively, when coadministered with rifampin. TheCmax, AUC0–t, and AUC0–infof M2 were also altered when bedaquiline was coadministered with rifapentine or rifampin. Single doses of bedaquiline, administered alone or with multiple doses of rifapentine or rifampin, were well tolerated, with no safety concerns related to coadministration. Daily administration of rifapentine to patients with tuberculosis presents the same drug interaction challenges as rifampin and other rifamycins. Strong inducers of the cytochrome P450 isoenzyme CYP3A4 should be avoided when considering the use of bedaquiline. (This study is registered at clinicaltrials.gov under identifier NCT02216331.)

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Phase I Safety, Pharmacokinetics, and Pharmacogenetics Study of the Antituberculosis Drug PA-824 with Concomitant Lopinavir-Ritonavir, Efavirenz, or Rifampin

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03332-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5245-5252 ◽

Cited By ~ 22

Author(s):

Kelly E. Dooley ◽

Anne F. Luetkemeyer ◽

Jeong-Gun Park ◽

Reena Allen ◽

Yoninah Cramer ◽

...

Keyword(s):

Phase I ◽

Geometric Mean ◽

Late Phase ◽

Clinical Implications ◽

First Line ◽

Time Curve ◽

Concentration Time ◽

A Minor ◽

To Receive ◽

Cyp 3A

ABSTRACTThere is an urgent need for new antituberculosis (anti-TB) drugs, including agents that are safe and effective with concomitant antiretrovirals (ARV) and first-line TB drugs. PA-824 is a novel antituberculosis nitroimidazole in late-phase clinical development. Cytochrome P450 (CYP) 3A, which can be induced or inhibited by ARV and antituberculosis drugs, is a minor (∼20%) metabolic pathway for PA-824. In a phase I clinical trial, we characterized interactions between PA-824 and efavirenz (arm 1), lopinavir/ritonavir (arm 2), and rifampin (arm 3) in healthy, HIV-uninfected volunteers without TB disease. Participants in arms 1 and 2 were randomized to receive drugs via sequence 1 (PA-824 alone, washout, ARV, and ARV plus PA-824) or sequence 2 (ARV, ARV with PA-824, washout, and PA-824 alone). In arm 3, participants received PA-824 and then rifampin and then both. Pharmacokinetic sampling occurred at the end of each dosing period. Fifty-two individuals participated. Compared to PA-824 alone, plasma PA-824 values (based on geometric mean ratios) for maximum concentration (Cmax), area under the concentration-time curve from 0 to 24 h (AUC0–24), and trough concentration (Cmin) were reduced 28%, 35%, and 46% with efavirenz, 13%, 17%, and 21% with lopinavir-ritonavir (lopinavir/r) and 53%, 66%, and 85% with rifampin, respectively. Medications were well tolerated. In conclusion, lopinavir/r had minimal effect on PA-824 exposures, supporting PA-824 use with lopinavir/r without dose adjustment. PA-824 exposures, though, were reduced more than expected when given with efavirenz or rifampin. The clinical implications of these reductions will depend upon data from current clinical trials defining PA-824 concentration-effect relationships. (This study has been registered at ClinicalTrials.gov under registration no. NCT01571414.)

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