Should
Antiretroviral Therapy Be Guided By Therapeutic Drug Monitoring? By
Liz Highleyman
 Inadequate
levels of antiretroviral drugs
in the body can lead to virological treatment failure, while excessive levels
can cause severe side effects.
Some experts advocate routine use of therapeutic
drug monitoring (TDM) to guide treatment decisions, but the benefits of measuring
plasma drug concentrations remain subject to controversy.
At
the at the 48th International Conference on Antimicrobial
Agents and Chemotherapy (ICAAC 2008) last month in Washington, DC, Italian
researchers presented results from a meta-analysis of studies looking at TDM to
assist treatment decision-making.  | TDM
Laboratory |
The
meta-analysis included randomized clinical trials comparing treatment guided by
TDM versus standard-of-care therapy without TDM. The outcomes of interest were
proportions of patients who received recommendations to change drug exposure levels,
proportions with undetectable HIV RNA, and proportions reaching target drug concentrations.
Results •
Data were included from 7 randomized trials,
with a total of 1046 patients, comparing TDM versus standard of care.
•
Fewer patients had their treatment changed
in TDM arms compared with standard of cafe (RR 0.64).
•
Compared with standard of care control
subjects, the likelihood of having a viral load below 200-500 copies/mL increased
over time in the TDM arms:
•
RR 0.91 at week 12;
•
RR 1.1 at week 24;
•
RR 1.38 at weeks 48-52.
•
When studies used a viral load cut-off
of 50 copies/mL, however, proportions of patients with undetectable viral load
were similar in the TDM and standard of care control arms both at week 24 (RR
1.13) and at weeks 48-52 (RR 1.05).
•
Likewise, proportions of patients achieving
target drug concentrations did not differ significantly in the TDM and control
groups (RR 1.04 at weeks 4-12; RR 2.29 at > 24 weeks).
Based
on these findings, the researchers concluded that, "Evidence for benefit
of TDM in randomized trials is limited to a reduction of rates of patients who
had recommendations to change drug exposure, and to long-term moderate improvement
of virological response." Ctr.
of Preventive Med., Verona, Italy; Dept. of Histology, Microbiology, and Med.
Biotechnology, Padua, Italy.
11/11/08
Reference
M
Crucian, S Parisi, G Serpelloni, and others. Should Antiretroviral Therapy Be
Guided By Therapeutic Drug Monitoring? A Meta-Analysis. 48th International Conference
on Antimicrobial Agents and Chemotherapy (ICAAC 2008). Washington, DC. October
25-28, 2008. Abstract H-4058. | 
