Pharmacokinetic Properties of Antiretroviral and Anti-Tuberculosis Drugs During Pregnancy and Postpartum

This study evaluated the pharmacokinetic (PK) properties of antiretroviral (ARV) and anti-tuberculosis (TB) drugs administered during pregnancy and postpartum.

IMPAACT 2026 was a Phase IV observational clinical study. Participants were not assigned to the drugs under study, but were already receiving the drugs for clinical care as prescribed by their clinical care providers. They were enrolled into study arms according to the drugs they were receiving through clinical care, and if on multiple drugs of interest, were able to enroll into multiple arms simultaneously. No ARVs or TB treatment drugs were supplied as part of this study. All drugs under study were provided by non-study sources. The study sponsor added this observational study to an existing investigational new drug (IND) number for off-label use in case the participant's clinical care provider decided to prescribe a higher dose than the approved dose if the PK results for the approved dose indicated that drug exposure may be inadequate.

This study was comprised of five components which in turn are comprised of arms specific to each drug or drug combination being evaluated:

• Component 1 (Arms 1.1, 1.2. 1.3. 1.4. and 1.5): Pregnant women living with HIV (WLHIV) receiving oral ARVs and no TB drugs, and their infants.
• Component 2 (Arm 2.1): Pregnant WLHIV and HIV-uninfected women who received long-acting/extended release ARVs during pregnancy, and their infants.
• Component 3 (Arms 3.1, 3.2, and 3.3): Pregnant WLHIV receiving ARVs and first-line TB treatment, and their infants.
• Component 4 (Arm 4.1): Pregnant WLHIV and HIV-uninfected women receiving second-line TB treatment, and their infants.
• Component 5 (Arms 5.1, 5.2. and 5.3): Postpartum WLHIV breastfeeding while receiving oral ARVs, and their infants.

Each arm was to open to accrual independently and accrue independently over approximately 36 months from the first enrollment in each arm. Participants signed a single informed consent for the Component to which they enrolled, and they could only enroll into one component. Women receiving more than one drug under study in a single Component (and their infants) were automatically enrolled into all relevant open arms within that component, based on the drugs under study they were receiving at study entry. There were no changes in arm during the study; a study inclusion criterion was that participants expected to remain on the same treatment regimen until study completion.

Participants in Component 1 were followed up to 12 weeks after delivery for mothers and up to 24 weeks after birth for infants. Participants in Component 2 were to be followed up to 5 weeks after delivery for mothers and infants. Participants in Components 3, 4, and 5 were followed up to 24 weeks after delivery for mothers and infants.

Study visits may include:

• Component 1: Maternal clinical and laboratory evaluations and PK sampling at second trimester (2T), third trimester (3T), delivery, and 6-12 weeks post-partum (PP). Infant clinical evaluations and washout PK sampling at birth and 5-9 days after birth.
• Component 2: Maternal clinical and laboratory evaluations and PK sampling at delivery. Infant clinical evaluations and washout PK sampling at birth, 5-9 days, and 12-16 days after birth. Maternal and infant breast milk transfer PK sampling at 5-9 days, 12-16 days, and 3-5 weeks after delivery.
• Component 3: Maternal clinical and laboratory evaluations and PK sampling at second trimester (2T), third trimester (3T), delivery, and 2-8 weeks post-partum (PP). Infant clinical evaluations and washout PK sampling at birth and 5-9 days after birth. Maternal and infant breast milk transfer PK sampling at 5-9 days, 2-8 weeks, and 16-24 weeks after delivery.
• Component 4: Maternal clinical and laboratory evaluations and PK sampling at second trimester (2T), third trimester (3T), delivery, and 2-8 weeks post-partum (PP). Infant clinical evaluations and washout PK sampling at birth and 5-9 days after birth. Maternal and infant breast milk transfer PK sampling at 5-9 days, 2-8 weeks, and 16-24 weeks after delivery.
• Component 5: Maternal and infant clinical evaluations and breast milk transfer PK sampling at 5-9 days, 2-12 weeks, and 16-24 weeks after delivery.

Component 2 (Arm 2.1) never opened for enrollment because investigations of the PK and safety of long-acting injectable cabotegravir in pregnancy were to be conducted in a separate study.

Arms 1.1 and 1.4 reached their enrollment targets and were closed to accrual. Arms 1.3 and 5.1 were closed to accrual per the decision of the Core Protocol Team because enrollment had slowed substantially and enough participants had been enrolled to proceed with data analysis and publication.

Arms 1.5, 3.2,3.3, 5.2, and 5.3 did not enroll any participants and were closed to accrual per the decision of the Core Protocol Team, because enrollment of enough participants to result in a publication was not anticipated.

The study was closed to accrual on March 5, 2025 at the recommendation of the IMPAACT Study Monitoring Committee (SMC). Prior to closure, 3 arms had open to accrual status: Arms 1.2, 3.1, and 4.1. The SMC suggested that the study objectives for Arm 3.1 could be achieved with the sample size at the time of closure and that the study objectives for Arms 1.2 and 4.1 could not be met within a reasonable timeframe.

Inclusion criteria

Component 1: Pregnant WLHIV receiving oral ARVs and no TB drugs, and their infants

• Mother is of legal age or otherwise able to provide independent informed consent as determined by site standard operating procedures (SOPs) and consistent with site institutional review board (IRB)/ethics committee (EC) policies and procedures, and is willing and able to provide written informed consent for her own and her infant's participation in this study.
• Prior to study entry, HIV status confirmed as HIV infected per study protocol.
• At study entry, pregnant and in one of the following two enrollment windows based on best available obstetrical estimate of gestational age:

• Second trimester: gestational age of 20 0/7 to 26 6/7 weeks
• Third trimester: gestational age of 30 0/7 to 37 6/7 weeks
• At study entry, receiving at least one of the following oral ARV drugs or drug combinations, based on maternal report and available medical records:

• Arm 1.1: Bictegravir (BIC) 50 mg q.d.
• Arm 1.2: Doravirine (DOR) 100 mg q.d.
• Arm 1.3: Tenofovir alafenamide (TAF) - 10 mg q.d. boosted with cobicistat
• Arm 1.4: TAF 25 mg q.d. without boosting
• Arm 1.5: TAF 25 mg q.d. boosted with cobicistat or ritonavir
• At study entry, planning to continue the current ARV regimen through at least 12 weeks post-delivery, based on maternal report and available medical records.
• At study entry, has been receiving the drug or drug combination under study at the required dose for at least two weeks, based on maternal report and available medical records.
• At study entry, assessed by study staff as having no identified barriers to completing initial PK sampling within 20 0/7 - 26 6/7 weeks gestation (second trimester) or 30 0/7 to 37 6/7 weeks gestation (third trimester) and within 14 days of enrollment.
• At study entry, if receiving a generic formulation of the drug or drug combination under study, approval of the formulation per study protocol.
• At study entry, not receiving any TB drugs (for either prophylaxis or treatment), based on maternal report and available medical records.

Component 2: Pregnant WLHIV and HIV-uninfected women who received long-acting/extended release ARVs during pregnancy, and their infants

• If of legal age or otherwise able to provide independent informed consent as determined by site SOPs and consistent with site IRB/EC policies and procedures: Willing and able to provide written informed consent for her own and her infant's participation in this study.
• If not of legal age or otherwise unable to provide independent informed consent as determined by site SOPs and consistent with site IRB/EC policies and procedures: Parent/guardian or other legally authorized representative of the mother and her infant is willing and able to provide written informed consent for the mother and her infant's study participation; in addition, when applicable, the mother is willing and able to provide written assent for her own and her infant's study participation.
• At study entry, intends to deliver at the study-affiliated clinic or hospital, based on maternal report.
• At study entry, gestational age of at least 24 0/7 weeks based on best available obstetrical estimate of gestational age, and not yet delivered.
• At study entry, has received at least one administration of the following, based on available medical records, during the current pregnancy:

• Arm 2.1: Long-acting injectable formulation of cabotegravir (CAB LA) (any dose)

Component 3: Pregnant WLHIV receiving ARVs with first-line TB treatment, and their infants

• Mother is of legal age or otherwise able to provide independent informed consent as determined by site SOPs and consistent with site IRB/EC policies and procedures, and is willing and able to provide written informed consent for her own and her infant's participation in this study.
• Prior to study entry, HIV status confirmed as HIV infected per study protocol.
• At study entry, pregnant and in one of the following two enrollment windows, based on best available obstetrical estimate of gestational age:

• Second trimester: gestational age of 20 0/7 to 26 6/7 weeks
• Third trimester: gestational age of 30 0/7 to 37 6/7 weeks
• At study entry, receiving at least two of the following first-line TB treatment drugs under study AND at least one of the following ARV drugs or drug combinations under study, based on maternal report and available medical records:

• First-line TB treatment drugs:
• Isoniazid (INH) 4-6 mg/kg (max 300 mg) q.d.
• Rifampin (RIF) 8-12 mg/kg (max 600 mg) q.d.
• Rifabutin (RFB) 150-300 mg q.d.
• Ethambutol (EMB) 15-20 mg/kg q.d.
• Pyrazinamide (PZA) 20-30 mg/kg q.d.
• Moxifloxacin (MFX) 400 mg or 800mg q.d
• ARVs:
• Arm 3.1: Dolutegravir (DTG) 50 mg b.i.d. when combined with RIF or 50 mg q.d. if RIF is not part of the TB regimen
• Arm 3.2: Atazanavir/ritonavir (ATV/r) ≥300/100 mg q.d. or Darunavir/ritonavir (DRV/r) ≥ 600/100 mg b.i.d.
• Arm 3.3: Lopinavir/ritonavir (LPV/r) 800/200 mg b.i.d.
• At study entry, has been receiving the drug combination under study at the required dose for at least two weeks based on maternal report and available medical records.
• At study entry, assessed by study staff as having no identified barriers to completing initial PK sampling within 20 0/7 - 26 6/7 weeks gestation (second trimester) or 30 0/7 to 37 6/7 weeks gestation (third trimester) and within 14 days of enrollment.
• At study entry, if receiving a generic ARV or TB formulation of the drug or drug combination under study, approval of the formulation per study protocol.
• At study entry, planning to continue the current ARV regimen through at least 8 weeks post-delivery, based on maternal report and available medical records.

Component 4 Inclusion Criteria: Pregnant WLHIV and HIV-uninfected women receiving second-line TB treatment, and their infants

• Mother is of legal age or otherwise able to provide independent informed consent as determined by site SOPs and consistent with site IRB/EC policies and procedures, and is willing and able to provide written informed consent for her own and her infant's participation in this study.
• Prior to study entry, HIV status confirmed as HIV-infected or HIV-uninfected, per study protocol.
• At study entry, pregnant and in one of the following two enrollment windows based on best available obstetrical estimate of gestational age:

• Second trimester: gestational age of 20 0/7 to 26 6/7 weeks
• Third trimester: gestational age of 30 0/7 to 37 6/7 weeks
• At study entry, receiving at least one of the following second-line TB treatment drugs under study, based on maternal report and available medical records:

• Arm 4.1: Second-line TB treatment drugs:
• Levofloxacin (LFX) 750mg - 1000mg q.d.
• Clofazimine (CFZ) 100mg q.d.
• Linezolid (LZD) 300mg - 600mg q.d.
• Bedaquiline (BDQ) 200mg t.i.w.
• Delamanid (DLM) 100mg b.i.d.
• Moxifloxacin (MFX) 400mg or 800mg q.d and at least one other second-line TB treatment drug under study
• At study entry, has been receiving the drugs under study at the required dose for at least two weeks, based on maternal report and available medical records.
• At study entry, assessed by study staff as having no identified barriers to completing initial PK sampling within 20 0/7 - 26 6/7 weeks gestation (second trimester) or 30 0/7 to 37 6/7 weeks gestation (third trimester) and within 14 days of enrollment.
• At study entry, if receiving a generic formulation of the drug(s) under study, approval of the formulation per study protocol.

Component 5: Postpartum WLHIV breastfeeding while receiving oral ARVs, and their infants

• Mother is of legal age or otherwise able to provide independent informed consent as determined by site SOPs and consistent with site IRB/EC policies and procedures, and is willing and able to provide written informed consent for her own and her infant's participation in this study.
• Prior to study entry, HIV status confirmed as HIV infected, per study protocol.
• At study entry, within 5-9 days post-delivery (inclusive).
• At study entry, breastfeeding mother-infant pair intends to continue exclusive breastfeeding through at least 16 weeks post-delivery.
• At study entry, mother is receiving any of the following oral ARV drugs or drug combinations:

• Arm 5.1: Atazanavir/ritonavir (ATV/r)
• Arm 5.2: Darunavir/ritonavir (DRV/r)
• Arm 5.3: Lopinavir/ritonavir (LPV/r)
• At study entry, mother has been receiving the drug(s) or drug combination(s) under study at the required dose for at least two weeks, based on maternal report and available medical records.
• At study entry, assessed by study staff as having no identified barriers to completing initial PK sampling within the 5-9 days post-delivery PK sampling window.
• At study entry, mother is planning to continue the current ARV regimen through at least 16 weeks post-delivery, based on maternal report and available medical records.
• At study entry, if receiving a generic ARV formulation of the drug or drug combination under study, approval of the formulation per study protocol.
• At study entry, infant weighs at least 1000 grams, based on available medical records.
• At study entry, infant does not have any severe congenital malformation or other medical condition not compatible with life or that would interfere with study participation or interpretation, as judged by the site investigator.

Components 1-4 Exclusion Criteria:

• At study entry, mother has received within the past 14 days medicines known to interfere with absorption, metabolism, or clearance of the drug or drug combination under study (see study protocol) based on maternal report and available medical records.

• Note: RIF is permitted for mothers in Components 3 and 4 being evaluated for TB and ARV drug interactions.
• At study entry, has a clinical or laboratory finding or condition that, in the opinion of the site investigator, is likely to require a change of the ARV or TB drug under study during the period of study follow-up.
• Arms 1.3, 1.4 and 1.5 only: At study entry, mother has received TDF-based therapy within the past 6 months.

Component 5 Exclusion Criteria

• Mother is currently enrolled in Components 1, 2, 3, or 4.
• At study entry, the mother or infant has received within the past 14 days medicines known to interfere with absorption, metabolism, or clearance of the drug or drug combination under study based on maternal report and available medical records (see study protocol).
• At study entry, mother or infant has a clinical or laboratory finding or condition that, in the opinion of the site investigator, is likely to require a change of the drug under study during study follow-up.