We carried out a retrospective chart review of patients in the respiratory care unit (RCU) at Jackson Memorial hospital in Miami, Florida. Inclusion criteria included: patients older than 18 years old, concomitant diagnosis of HIV and active TB, receiving DTG and RBN, and undergoing measurement of DTG and RBN plasma concentrations. Furthermore, the adherence of these medications is high as these patients were evaluated in the inpatient setting where administration of medications is monitored by clinicians.
On admission to RCU, the patients are started on a TB regimen and undergo PK sampling 2 weeks after the regimen is established. When changes are made to the TB medications, or HIV medications are added, a repeat sampling is done. Blood sampling is done when fasting.
DTG: Samples are drawn at the end of dosing interval to assess trough plasma concentration (Cmin) and at 2 and 6 h to assess peak (Cmax) concentration. The typical DTG peak and trough concentrations are approximately 3.3 mcg/mL and 0.80 mcg/mL, respectively.   However, we do agree that there is an acceptable range and trough concentrations that may be higher than the in vitro protein-adjusted IC90 for wild-type virus.
RBN: Samples are drawn at 3 and 7 h to assess peak plasma concentration (Cmax) to capture either early or delayed absorption. Expected concentrations are 0.45-0.9 mcg/mL.  
Blood samples were sent to the Infectious Disease Pharmacokinetics Lab at the University of Florida in Gainesville, Florida. Phoenix  WinNonlin  v.8.0 (Certara USA, Inc., Princeton, NJ, USA) was used to perform the non-compartmental analysis and calculate the area under the concentration-time curve (AUC) for DTG and RBN. The area under the concentration-time curve for the dosing interval (AUC0-tau) and 24-h period (AUC0-24) were calculated. AUC0-tau and AUC0-24 were extrapolated from the elimination phase captured during the PK sampling of each drug. If the elimination phase was not captured during that time, the AUC0-last sample was reported instead. Tables 1 and 2 shows the calculated AUCs for DTG and RBN. In addition to therapeutic drug monitoring (TDM), patients underwent blood collection for evaluation of CD4+ cells and viral loads.
Our study was approved by the institutional review board, University of Miami, Jackson Memorial Hospital; number: 20191069. This is a retrospective study with chart review for data collection; no written informed consent was required by the institution.