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The relationship between ritonavir plasma trough concentration and virological and immunological response in
1I Department of Infectious Diseases c/o G. Gaslini Institute - University of Genoa, Genoa, Italy. gatti@vpharm.com
Insights
Higher ritonavir (RTV) trough concentrations may predict better virological response in HIV-positive children. Further studies are needed to confirm this trend and optimize protease inhibitor therapy in pediatric patients.
Area of Science:
- Pediatric Infectious Diseases
- Pharmacodynamics
- HIV/AIDS Research
Background:
- Assessing factors predicting therapeutic response to ritonavir (RTV) in HIV-positive children.
- Evaluating the role of RTV plasma levels in treatment efficacy.
Purpose of the Study:
- To investigate the relationship between RTV plasma concentrations and virological response in HIV-positive children.
- To identify predictors of treatment response in this population.
Main Methods:
- Study included 11 HIV-positive children, NRTI-experienced and PI-naive, on RTV plus two NRTIs.
- Measured demographic parameters, baseline CD4 counts, and viral load.
- Determined RTV peak and trough plasma concentrations at steady-state.
- Quantified virological response as viral load change at 6 months (Delta(6)).
Main Results:
- Median Delta(6) was 0.88 log10 copies/mL.
- Peak RTV: 14.9 mg/L; Trough RTV: 5.0 mg/L.
- Higher trough RTV concentrations showed a trend towards greater viral load reduction (Delta(6)), though not statistically significant (r = 0.56, P = 0.075).
Conclusions:
- A trend suggests higher RTV trough concentrations correlate with improved viral load decrease in pediatric HIV patients.
- Further pharmacodynamic studies are warranted to explore protease inhibitor efficacy in children.
- This highlights the potential importance of therapeutic drug monitoring for RTV in pediatric HIV management.
Background:
We studied a number of factors, including ritonavir plasma levels, and their capability of predicting response to therapy with ritonavir (RTV).
Methods:
Eleven HIV-positive children, nucleoside reverse transcriptase inhibitor (NRTI)-experienced, protease inhibitor (PI) naive, receiving RTV in combination with two NRTIs were enrolled in the study. Demographic parameters were: median age (range) 10 (2-13) years, weight 26 (10-38) kg, body surface area (BSA) 0.93 (0.47-1.21) m(2). Baseline values of CD4, percent CD4 and viral load were 137 (2-1390) cells/microL, 9.5 (0.4-32.4)%, and 5.15 (4.30-6.18) log10 copies/mL, respectively. The dose of RTV was 318 (266-409) mg/m(2) twice daily. Peak (3.5 h after administration) and trough (predose) plasma concentrations of RTV were determined on one occasion at steady-state after a morning dose. Virological response to treatment was quantified as the difference between the baseline value of viral load and the value observed at 6 months of therapy (Delta(6)).
Results:
The relationship between Delta(6) and demographic parameters (age, weight, BSA, and baseline CD4, percent CD4, and viral load) and plasma concentrations of RTV was studied by linear regression. Median (range) Delta(6) was 0.88 (0.77-2.62) log10 copies/mL. Peak and trough of RTV were 14.9 (3.2-31.4) and 5.0 (0.1-15.6) mg/L, respectively. Trough concentration of RTV was the best predictor of Delta(6), although the relationship between these two variables was not statistically significant (r = 0.56, P = 0.075).
Conclusion:
Our observation of a trend for a greater decrease in viral load in patients with higher trough concentration of RTV warrants further pharmacodynamic studies of PI in paediatric patients.
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