Abacavir 600 mg, Dolutegravir 50 mg, Lamivudine 300 mg Tablets

TRIUMEQ and TRIUMEQ PD are a fixed-dose combination of the HIV‑1 antiretroviral agents abacavir, dolutegravir, and lamivudine [see Microbiology (12.4)].

Pharmacokinetics in Adults — One TRIUMEQ tablet was bioequivalent to one dolutegravir (TIVICAY) tablet (50 mg) plus one abacavir and lamivudine fixed-dose combination tablet (EPZICOM) under fasted conditions in healthy subjects (n = 62).

TRIUMEQ tablets and TRIUMEQ PD tablets for oral suspension are bioequivalent for the abacavir and lamivudine components, but not for the dolutegravir component. The relative dolutegravir bioavailability of TRIUMEQ PD is approximately 1.7-fold higher than TRIUMEQ; therefore, the 2 dosage forms are not substitutable on a milligram-per-milligram basis [see Dosage and Administration (2.3), Warnings and Precautions (5.7)]. The relative dolutegravir bioavailability is expected to be similar between TRIUMEQ PD and TIVICAY PD.

Abacavir: Following oral administration, abacavir is rapidly absorbed and extensively distributed. After oral administration of a single dose of 600 mg of abacavir in 20 subjects, Cmax was 4.26 ± 1.19 mcg/mL (mean ± SD) and AUC∞ was 11.95 ± 2.51 mcg•hour/mL. Binding of abacavir to human plasma proteins is approximately 50% and was independent of concentration. Total blood and plasma drug‑related radioactivity concentrations are identical, demonstrating that abacavir readily distributes into erythrocytes. The primary routes of elimination of abacavir are metabolism by alcohol dehydrogenase to form the 5′‑carboxylic acid and glucuronyl transferase to form the 5′‑glucuronide. In single-dose trials, the observed elimination half-life (t½) was 1.54 ± 0.63 hours. After intravenous administration, total clearance was 0.80 ± 0.24 L/h/kg (mean ± SD).

Dolutegravir: Following oral administration of dolutegravir, peak plasma concentrations were observed 2 to 3 hours postdose. With once-daily dosing, pharmacokinetic steady state is achieved within approximately 5 days with average accumulation ratios for AUC, Cmax, and C24 h ranging from 1.2 to 1.5. Dolutegravir is a P-gp substrate in vitro. The absolute bioavailability of dolutegravir has not been established. Dolutegravir is highly bound (≥98.9%) to human plasma proteins based on in vivo data and binding is independent of plasma concentration of dolutegravir. The apparent volume of distribution (Vd/F) following 50-mg once-daily administration is estimated at 17.4 L based on a population pharmacokinetic analysis.

Dolutegravir is primarily metabolized via UGT1A1 with some contribution from CYP3A. After a single oral dose of [14C] dolutegravir, 53% of the total oral dose is excreted unchanged in the feces. Thirty-one percent of the total oral dose is excreted in the urine, represented by an ether glucuronide of dolutegravir (18.9% of total dose), a metabolite formed by oxidation at the benzylic carbon (3.0% of total dose), and its hydrolytic N-dealkylation product (3.6% of total dose). Renal elimination of unchanged drug was <1% of the dose. Dolutegravir has a terminal half-life of approximately 14 hours and an apparent clearance (CL/F) of 1.0 L/h based on population pharmacokinetic analyses.

The pharmacokinetic properties of dolutegravir have been evaluated in healthy adult subjects and HIV‑1–infected adult subjects. Exposure to dolutegravir was generally similar between healthy subjects and HIV‑1–infected subjects.

Cerebrospinal Fluid (CSF): In 11 treatment-naive subjects on dolutegravir 50 mg daily plus abacavir/lamivudine, the median dolutegravir concentration in CSF was 18 ng/mL (range: 4 ng/mL to 23.2 ng/mL) 2 to 6 hours postdose after 2 weeks of treatment. The clinical relevance of this finding has not been established.