Intracellular NRTI-triphosphate levels in children are similar to adults

Polly Clayden, HIV i-Base

A poster from G Kruse and colleagues from the University of Frankfurt, presented findings from a study analysing intracellular NRTI-triphosphate (TP) levels of 3TC, ddI, d4T, CBV, TDF and FTC simultaneously, using a newly established validated HPLC-MS/MS method.

The authors quantified 69 intracellular NRTI-TP concentrations from 53 PBMC samples from 14 children age 14 months to 16 years. Results of the number of total (T) and evaluable (E) samples, the mean triphosphate concentrations and ranges all in fmol/mio cells are shown in Table 1.

Table 1: Total (T) and evaluable (E) intracellular TP levels

T E mean range
3TC 18 18 6380 776-12340
FTC 15 15 2780 700-5330
CBV 9 6 185 28-465
TDF 5 5 186 89-247
ddi 30 24 82 5-176
d4t 6 1 19

They noted that not all NRTI-TP in all samples could be quantified due to lower limit of quantification of this assay and the amount of blood that can be taken from children.

The authors wrote that these results are very similar to reported results in adults and there is no indication of major differences between these groups. This assay can simultaneously quantify all the nucleoside triphosphates except for AZT and appears to be relatively simple compared to more “challenging and complex analytical methods”.


Kruse G, Konigs C, Stumppf S et al. Intracellular NRTI-triphosphate levels of 3TC, ddI, d4T CBV, TDF and FTC in HIV-infected children. 6th International Workshop on Clinical Pharmacology of HIV Therapy. 28-30 April 2005. Quebec. Abstract 43.

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