Rme. Van Praag et al., Enhanced penetration of indinavir in cerebrospinal fluid and semen after the addition of low-dose ritonavir, AIDS, 14(9), 2000, pp. 1187-1194
Objective: Penetration of antiretroviral drugs into anatomical HIV-1 reserv
oirs such as the male genital tract and the central nervous system is impor
tant. Data on indinavir (IDV) concentrations in seminal plasma are lacking
and IDV concentrations in cerebrospinal fluid are at best borderline.
Design: Thirteen patients were treated with zidovudine (or stavudine), lami
vudine, abacavir, nevirapine and IDV (1000 mg three times daily). When nevi
rapine led to low IDV concentrations, IDV was changed into the combination
IDV/ritonavir (RTV) 800/ 100 mg twice daily to improve the pharmacokinetic
profile of IDV.
Methods: A serum pharmacokinetic profile, a semen sample and a cerebrospina
l fluid sample were collected at weeks 8, 24, 48 and 72.
Results: Addition of RTV increased the median IDV trough concentration in s
erum from 65 to 336 ng/ml (P = 0.005). Median IDV concentration in seminal
plasma increased from 141 to 1634 ng/ml (P = 0.002) (n = 9) and in cerebros
pinal fluid from 39 (n = 12) to 104 (n = 7) ng/ml (P<0.001). In six patient
s with samples collected both before and after the addition of RTV the IDV
concentration in seminal plasma increased 8.2 times [95% confidence interva
l (CI) 5.2-11.6], and in cerebrospinal fluid 2.4 times (95% CI 1.8-3.9).
Conclusions: IDV penetrates well into the male genital tract. The addition
of low-dose RTV not only increases IDV concentrations in serum but also in
seminal plasma and cerebrospinal fluid, thereby probably improving the pote
ncy of the regimen in these anatomical HIV reservoirs. Higher serum trough
levels alone can not sufficiently explain the observed increases in seminal
plasma and cerebrospinal fluid concentrations. Inhibition of P-glycoprotei
n-mediated transport by RTV might be an additional mechanism. (C) 2000 Lipp
incott Williams & Wilkins.