Drug Interaction Study

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the exposure of rifabutin (RIB) when administered with atazanavir and ritonavir (ATV/RTV)

Official Title
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Study to Evaluate the Exposure of Rifabutin Administered in an Alternate Regimen in Combination With Atazanavir and Ritonavir Healthy Subjects

Conditions
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Antivirals/HIV

Intervention / Treatment
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* Drug: Rifabutin
* Drug: Rifabutin + Atazanavir + Ritonavir


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy male and female subjects between the ages of 18 to 50 years old with a body mass index (BMI) of 18 to 32 kg/m² Prior to enrollment, subjects must have physical and laboratory test findings within the normal limits, and women of childbearing potential (WOCBP) must have a negative pregnancy test Exclusion Criteria: Any significant acute or chronic medical illness Evidence of organ dysfunction or any clinically significant deviation from normal in physical examination, vital signs, electrocardiogram (ECG) or clinical laboratory determinations Use of any prescription drugs or over-the-counter acid controllers within 4 weeks prior to study drug administration Use of any other drugs, including over-the-counter medications of herbal preparations within 1 week prior to study drug administration

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: A<br> | Drug: Rifabutin<br>* Capsule, Oral, 150 mg, once daily, 11 Days<br>|
| Active Comparator: B<br> | Drug: Rifabutin + Atazanavir + Ritonavir<br>* Capsules, Oral, 18 Days Rifabutin (150 mg, 2x/wk) Atazanavir (300 mg, once daily) Ritonavir (100 mg, once daily)<br>* Other names: Reyataz;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Average Area Under the Plasma Concentration-time Curve for 24 Hours (AUC24avg) for Rifabutin (RIB) | AUC24avg is AUC(0-24 hour) following dosing on Day 10 for RIB 150mg once daily (QD); AUC24avg is the area under the plasma concentration-time curve in 1 dosing interval (AUC[TAU]) divided by the number of days over the sampling duration for ATV/RTV 300/100 mg QD+RIB 150 mg twice weekly, i.e. AUC(TAU)/7. | Pre-dose (0 hours [h]) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Maximum Plasma Concentration (Cmax) of RIB | Cmax was derived from plasma concentration versus time for RIB and was recorded directly from experimental observations for each treatment period. | Pre-dose (0h) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Minimum Plasma Concentration (Cmin) of RIB | Cmin was derived from plasma concentration versus time for RIB. | Pre-dose (0h) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| AUC24avg for 25-O-Desacetyl-RIB | AUC24avg is AUC(0-24 hour) following dosing on Day 10 for RIB 150 mg QD; AUC24avg is the area under the plasma concentration-time curve in 1 dosing interval (AUC[TAU]) divided by the number of days over the sampling duration for ATV/RTV 300/100 mg QD+RIB 150 mg twice weekly, i.e. AUC(TAU)/7 | Pre-dose (0h) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Cmax of 25-O-Desacetylrifabutin (25-O-Desacetyl-RIB) | Cmax was derived from the plasma concentration versus time for 25-O-Desacetyl-RIB (a metabolite of RIB) and was recorded directly from experimental observations for each treatment period. | Pre-dose (0h) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Cmin of 25-O-Desacetyl-RIB | Cmin was derived from plasma concentration versus time for 25-O-Desacetyl-RIB. | Pre-dose (0h) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Total Area Under the Plasma Concentration-time Curve (AUCtot) | AUCtot represents the total free RIB plus 25-O-Desacetyl-RIB output. It is calculated as: AUCtot (micromolar[µM]*h) = AUC24avg(RIB)(ng*h/mL)/847.016 (g/mole) + AUC24avg(25-O-Desacetyl-RIB)(ng*h/mL)/804.979(g/mole). The 300 mg RIB arm represents an extrapolation from the 150 mg RIB group. | Pre-dose (0h) on Days 6, 8, 10, and 11, and post-dose (1h,2h,3h,4h,6h,8h,12h) on Day 10 for RIB 150 mg QD; and pre-dose (0h) on Days 4, 8,11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cmax of ATV | Cmax was derived from the plasma concentration versus time for ATV and was recorded directly from experimental observations for each treatment period. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Cmin of ATV | Cmin was derived from the plasma concentration versus time for ATV. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| AUC(TAU) for ATV | AUC(TAU) was derived from the plasma concentration versus time for ATV, and was calculated by linear and log-linear trapezoidal summations using a mixed log-linear algorithm. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Time to Reach Maximum Observed Plasma Concentration (Tmax) of ATV | Tmax was derived from the plasma concentration versus time for ATV and was recorded directly from experimental observations for each treatment period. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Terminal Elimination Half-life (T-half) of ATV | T-half was obtained directly from the concentration-time data. T-half following doses administered for treatment ATV/RTV 300/100 mg QD+RIB 150 mg twice weekly. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Cmax of RTV | Cmax was derived from the plasma concentration versus time for RTV and was recorded directly from experimental observations for each treatment period. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Cmin of RTV | Cmin was derived from the plasma concentration versus time for RTV. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| AUC(TAU) for RTV | AUC(TAU) was derived from the plasma concentration versus time for RTV, and was calculated by linear and log-linear trapezoidal summations using a mixed log-linear algorithm. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Tmax of RTV | Tmax was derived from the plasma concentration versus time for RTV and was recorded directly from experimental observations for each treatment period. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| T-half of RTV | T-half was obtained directly from the concentration-time data. | Pre-dose (0h) on Days 4, 8, 11 to 18 and post-dose (1h,2h,3h,4h,6h,8h,12h) on Days 11 and 15 for ATV/RTV + RIB. | 
| Number of Participants Who Died, Experienced Other Serious Adverse Events (SAEs), Experienced Adverse Events (AEs) and Experienced Events Leading to Discontinuation. | AEs were defined as new, untoward medical occurrences/worsening of pre-existing medical condition, whether drug-related or not. SAEs were defined as any AE that: resulted in death; was life threatening; resulted in a persistent or significant disability/incapacity; resulted in/prolonged an existing in-patient hospitalization; was a congenital anomaly/birth defect; was a cancer; or was an overdose. Discontinuation from the study was due either to an AE or was conducted at the investigator's discretion. | From Day 1 to 30 days after the last dose of study drug. | 
| Number of Participants With Marked Abnormalities (MAs) in Hematology: Hemoglobin, Hematocrit, Platelet Count and Leukocytes | MAs are laboratory measurements marked as abnormal, per pre-defined study criteria, at any study time point. The following hematology MA definitions specify the criteria for the data presented. Hemoglobin/hematocrit: <0.85 x pre-treatment (pre-Rx) value. Platelet count: <0.85 x lower limit of normal (LLN) (or, if pre-Rx value <LLN, then <0.85 x pre-Rx value) or >1.5 x upper limit of normal (ULN). Leukocytes: <0.9 x LLN or >1.2 x ULN (or, if pre-Rx value <LLN, then <0.85 x pre-Rx or >ULN. If pre-Rx value >ULN, then >1.15 x pre-Rx or <LLN). | Pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14, 20 and 26 for RIB 150 mg QD; and pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14 and 18 for ATV/RTV 300/100 mg QD + RIB 150 mg twice weekly. | 
| Number of Participants With MAs in Hematology: Neutrophils + Bands (Absolute), Lymphocytes (Absolute), Monocytes (Absolute), Basophils (Absolute) and Eosinophils (Absolute) | MAs are laboratory measurements marked as abnormal, per pre-defined study criteria, at any study time point. The following hematology MA definitions specify the criteria for the data presented. Neutrophils+bands (absolute): <=1.50 x 10^3 cells/microliter (uL). Lymphocytes (absolute): <0.75 x 10^3 cells/uL or >7.50 x 10^3 cells/uL. Monocytes (absolute): >2.00 x 10^3 cells/uL. Basophils (absolute): >0.40 x 10^3 cells/uL. Eosinophils (absolute): >0.75 x 10^3 cells/uL. | Pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14, 20 and 26 for RIB 150 mg QD; and pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14 and 18 for ATV/RTV 300/100 mg QD + RIB 150 mg twice weekly. | 
| Number of Participants With MAs in Serum Chemistry: Alkaline Phosphatase (ALP),Aspartate Aminotransferase (AST),Alanine Aminotransferase (ALT),Bilirubin (Total),Bilirubin (Direct),Blood Urea Nitrogen (BUN),Creatinine,Sodium (Serum),Potassium (Serum) | MAs=laboratory measurements marked as abnormal, per pre-defined study criteria, at any study time point. The following serum chemistry MA definitions specify MA criteria. ALP, AST, ALT:>1.25xULN (if pre-Rx >ULN, then >1.25xpre-Rx). Bilirubin (total), bilirubin (direct), BUN:>1.1xULN (if pre-Rx >ULN, then >1.25xpre-Rx). Creatinine:>1.33xpre-Rx. Sodium (serum):<0.95xLLN or >1.05xULN (if pre-Rx <LLN, then <0.95xpre-Rx or >ULN. If pre-Rx >ULN, then >1.05xpre-Rx or <LLN). Potassium (serum):<0.9xLLN or >1.1xULN (if pre-Rx <LLN, then <0.9xpre-Rx or >ULN. If pre-Rx >ULN, then >1.1xpre-Rx or <LLN). | Pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14, 20 and 26 for RIB 150 mg QD; and pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14 and 18 for ATV/RTV 300/100 mg QD + RIB 150 mg twice weekly. | 
| Number of Participants With MAs in Serum Chemistry: Chloride (Serum), Calcium (Total), Protein (Total), Bicarbonate, Phosphorous (Inorganic) | MAs=laboratory measurements marked as abnormal, per pre-defined study criteria, at any study time point. The following serum chemistry MA definitions specify MA criteria. Chloride (serum), calcium (total), protein (total):<0.9xLLN or >1.1xULN (if pre-Rx <LLN, then <0.9xpre-Rx or >ULN. If pre-Rx >ULN, then >1.1xpre-Rx or <LLN). Bicarbonate:<0.8xLLN or >1.2xULN (if pre-Rx value <LLN, then <0.8xpre-Rx value or >ULN. If pre-Rx >ULN, then >1.2xpre-Rx value or <ULN). Phosphorous (inorganic):<0.85xLLN or >1.25xULN (if pre-Rx <ULN, then <0.85xpre-Rx or <ULN. If pre-Rx >ULN, then >1.25x re-Rx or <LLN). | Pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14, 20 and 26 for RIB 150 mg QD; and pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14 and 18 for ATV/RTV 300/100 mg QD + RIB 150 mg twice weekly. | 
| Number of Participants With MAs in Serum Chemistry: Glucose (Fasting Serum), Albumin, Creatine Kinase, Uric Acid, Lactate Dehydrogenase (LDH) | MAs=laboratory measurements marked as abnormal, per pre-defined study criteria, at any study time point. The following serum chemistry MA definitions specify MA criteria. Glucose (fasting serum): <0.8 x LLN or >1.5 ULN (if pre-Rx <LLN, then <0.8 x pre-Rx or >ULN. If pre-Rx >ULN, then >2.0 x pre-Rx or <LLN. Albumin: <0.9 x LLN (if pre-Rx <LLN, then <0.9 x pre-Rx). Creatine kinase: >1.5 x ULN (if pre-Rx >ULN, then >1.5 x pre-Rx). Uric acid: >1.2 x ULN (if pre-Rx >ULN, then >1.25 x pre-Rx). LDH: >1.25 x ULN (if pre-Rx >ULN, then >1.5 x pre-Rx). | Pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14, 20 and 26 for RIB 150 mg QD; and pre-dose on Day -1 and post-dose on Days 3, 7, 11, 14 and 18 for ATV/RTV 300/100 mg QD + RIB 150 mg twice weekly. | 
| Number of Participants With MAs in Urinalysis | MAs are laboratory measurements marked as abnormal, per pre-defined study criteria, at any study time point. The following definitions specify the criteria for MAs. Protein, glucose and blood: >=2+ (or, if pre-treatment value >=1+, then >= 2 x pre-treatment value). | Pre-dose on Day -1, Day 7 and discharge. | 
| Number of Participants With Identified Electrocardiogram (ECG) Abnormalities | ECG abnormalities were defined as findings that are clinically meaningful as judged by the investigator. A 12-lead ECG was recorded at least 5 minutes after the participant had been lying down and all ECG recordings were evaluated by the investigator. Abnormalities, if present at any study time point, were listed. | Pre-dose on Day -1 and study discharge. | 
| Number of Participants With Clinically Significant Vital Signs or Physical Examination Findings | Vital signs assessments and physical examination were conducted throughout the study. Vital signs assessments included body temperature, respiratory rate, blood pressure (systolic and diastolic), and heart rate. Physical examination included a neurological examination (if ocular signs or symptoms occurred, a reflex to slit lamp exam was performed by an ophthalmologist). The investigator used his/her clinical judgment to decide whether or not abnormalities in vital signs or physical examination were clinically meaningful. | Vital signs:screening, prior to dosing on Day 1, Day 7, study discharge. Physical examination:screening, Day -1, Day 7, study discharge |