Dolutegravir Half-Life
The terminal elimination half-life of dolutegravir is approximately 14 hours 1.
Pharmacokinetic Details
According to FDA labeling data, dolutegravir demonstrates the following elimination characteristics 1:
- Terminal half-life: ~14 hours based on population pharmacokinetic analyses
- Apparent clearance (CL/F): 1.0 L/hour
- Time to steady state: ~5 days with once-daily dosing
- Peak plasma concentrations (Tmax): 2-3 hours post-dose
Extended Elimination After Treatment Cessation
The elimination profile becomes more complex after drug cessation. Research data shows that the terminal elimination half-life extends to approximately 23.1 hours when measured to the last detectable concentration (up to 216 hours post-dose), compared to 14.3 hours within the standard dosing interval 2. This prolonged elimination means:
- Dolutegravir concentrations remain above the protein-adjusted IC90 (64 ng/mL) in 100% of subjects at 36-48 hours after the last dose
- 94% of subjects maintain therapeutic levels at 60-72 hours post-dose
- All subjects had detectable concentrations at 96 hours (4 days) after stopping treatment 2
Clinical Implications of the Half-Life
Dosing Forgiveness
The 14-hour half-life provides substantial pharmacokinetic forgiveness for missed doses, particularly compared to shorter-acting integrase inhibitors. This extended coverage above therapeutic thresholds for 3-4 days after cessation offers a buffer against occasional non-adherence 2, 3.
Special Populations
Pregnancy: The half-life characteristics change during pregnancy. In neonates exposed to dolutegravir in utero, the median elimination half-life extends to 32.8 hours—more than twice that of adults—due to immature hepatic metabolism 4. In premature neonates, this can extend even further to approximately 4-fold longer than adults when combined with metabolic inhibitors like atazanavir 5.
Metabolic considerations: Dolutegravir is primarily metabolized via UGT1A1 with minor CYP3A4 contribution. Individuals with UGT1A1 genotypes conferring poor metabolism show 32% lower clearance and 46% higher AUC, though this doesn't typically require dose adjustment 1.
Steady-State Characteristics
With the 14-hour half-life and once-daily dosing:
- Accumulation ratios range from 1.2 to 1.5 for AUC, Cmax, and C24h
- Steady state is reliably achieved within approximately 5 days 1
- Trough concentrations (C24h) at steady state are 1.11 mcg/mL with 50 mg once daily, well above the therapeutic threshold 1
This pharmacokinetic profile—combining a 14-hour terminal half-life with high protein binding (≥98.9%) and extensive tissue distribution—contributes to dolutegravir's robust efficacy and forgiving dosing characteristics in clinical practice 1, 3.