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A randomised, double-blind, placebo-controlled, clinical trial to compare the safety and efficacy of reduced dose efavirenz (EFV) with standard dose EFV plus 2N(t)RTI in antiretroviral-naive HIV-infected individuals over 96 weeks. Encore1 intensive pharmacokinetics sub-study

A randomised, double-blind, placebo-controlled, clinical trial to compare the safety and efficacy of reduced dose efavirenz (EFV) with standard dose EFV plus 2N(t)RTI in antiretroviral-naive HIV-infected individuals over 96 weeks. Encore1 intensive pharmacokinetics sub-study

Status
Active, not recruiting
Phases
Phase 3
Study type
Interventional
Source
ANZCTR
Registry ID
ACTRN12612000263897
Acronym
Encore1 intensive PK sub-study
Enrollment
40
Registered
2012-03-05
Start date
2011-12-20
Completion date
Unknown
Last updated
2026-02-04

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

None listed

Brief summary

Safety and efficacy are key issues in antiretroviral therapy (ART) selection. Efavirenz (EFV) is an important component of combination ART in treatment naive individuals. Like many drugs, EFV demonstrates inter-individual differences in its efficacy and tolerability. The Encore1 study provides an opportunity to examine the pharmacokinetics (PK)(processes by which a drug is absorbed, distributed, metabolized, and eliminated by the body) of EFV in blood samples collected over a 24-hour dosing interval in participants receiving either standard 600 mg or reduced 400 mg dose EFV once daily. This sub-study will investigate the relationships between EFV dosage, EFV plasma concentrations, toxicity and virological efficacy. EFV concentrations in dried blood spots and matched plasma and will be evaluated to determine the utility of dried blood spot measurements in measuring EFV plasma concentrations. Measurements dried blood spots could potentially be a cheap and easy alternative to measurements in plasma. Dried blood spots can be easily collected from venous blood or fingerprick, do not need plasma separation and potentially need less stringent storage conditions during shipment. http://clinicaltrials.gov/ct2/show/NCT01271894?term=Encore1&rank=3

Interventions

Efavirenz 600 mg orally once daily or efavirenz 400 mg orally once daily in combination with daily tenofovir/emtricabine (300/200 mg) fixed-drug combination for 96 weeks http://clinicaltrials.gov/ct2/show/NCT01011413?term=Encore1&rank=2

Sponsors

Kirby Institute/University of New South Wales
Lead SponsorUniversity

Study design

Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used)

Eligibility

Sex/Gender
All
Age
16 Years to No maximum
Healthy volunteers
No

Inclusion criteria

Main study participants at selected sites are eligible: provide written sub-study consent at or before week 0 taken randomized study drugs for at least 4 weeks but less than 8 weeks taken EFV in the evening for at least 7 days taken all EFV doses over the 3 preceding days.

Exclusion criteria

nil

Outcome results

None listed

Source: ANZCTR · Data processed: Feb 4, 2026