Limited penetration of lopinavir into seminal plasma of HIV-1-infected men

Antiretroviral therapy can decrease the amount of HIV-1 RNA in blood plasma and in semen [1]. However, the decline of the HIV-1-RNA concentration and the evolution of virus in semen during therapy can show discordance with blood plasma, indicating viral compartmentalization [2,3]. Poor penetration into the male genital tract by some antiretroviral drugs can contribute to the different viral dynamics in this compartment [4]. Data available on drug concentrations in semen show that the penetration of the protease inhibitors (PI) nelfinavir, ritonavir and saquinavir is poor [5]. The nucleoside analogues zidovudine, stavudine, lamivudine and abacavir, the non-nucleoside reverse transcriptase inhibitors nevirapine and efavirenz, and the PI indinavir and amprenavir penetrate well into the male genital tract [3,6–12]. There are no data on the penetration of the PI lopinavir into the male genital tract. HIV-1-infected men who were on a lopinavir-containing regimen for a minimum of 4 weeks were recruited from our HIV outpatient clinic. The patients had to have no signs or symptoms of a genital infection. Semen samples were obtained by masturbation, centrifuged between 2 and 4 h after collection at 1200 g for 10 min to obtain seminal plasma and stored at −70°C until analysis. Within 2 h after semen collection, a blood sample was taken for the measurement of the blood plasma lopinavir and HIV-1-RNA concentrations. The local Medical Ethics Committee approved the study, and written informed consent was obtained from all patients. HIV-1 RNA in ethylenediamine tetraacetic acid plasma was measured using the quantiplex bDNA assay (Bayer Corporation, Diagnostics Division, Emeryville, CA, USA), with a lower limit of quantification of 50 copies/ml. HIV-1 RNA in seminal plasma was measured using the ultra Nuclisens HIV-1 QT assay (Organon Teknika, Boxtel, the Netherlands), with a lower limit of quantification of 50 copies/ml. Lopinavir concentrations in heparinized blood plasma and in seminal plasma were measured using a high-performance liquid chromatographic procedure [13]. The intra- and interday variation of this assay was less than 5%. Fourteen patients on a lopinavir-containing regimen for a median of 16 weeks (range 4–41 weeks) were included in this study. Lopinavir was started in nine of the patients because of virological failure on their previous antiretroviral regimen and in five because of side-effects of their previous regimen. The five patients who switched therapy because of side-effects had an undetectable HIV-1-RNA level in blood plasma at the moment of switching therapy. At the time the study samples were taken all five patients still had an undetectable HIV-1-RNA level in blood plasma and an undetectable HIV-1-RNA level in seminal plasma. Of the nine patients starting lopinavir because of virological failure, four had a detectable HIV-1-RNA level in blood plasma at the time the study samples were taken. These patients were not yet in a steady state, and during follow-up their blood plasma HIV-1-RNA levels decreased further. Only one of these four patients had an undetectable HIV-1-RNA level in seminal plasma. The other five patients starting lopinavir because of virological failure had an undetectable blood plasma HIV-1-RNA level. One of these patients had a detectable HIV-1-RNA level in seminal plasma. In five of the 14 patients the blood plasma concentration of lopinavir was below the desired concentration of 5.0 mg/l (Abbott product information). The other nine patients had a plasma concentration greater than 5.0 mg/l (Fig. 1a).Fig. 1.: Lopinavir concentrations in (a) blood plasma and (b) seminal plasma versus time after medication intake. ○ Detectable HIV-1-RNA levels in blood plasma; ● undetectable HIV-1-RNA levels in blood plasma and seminal plasma. (c) Ratio of the concentration of lopinavir in seminal plasma and blood plasma.The lopinavir concentration in seminal plasma ranged between 0.046 and 3.9 mg/l [median 0.23 mg/l, interquartile range (IQR) 0.15–0.33]. No relationship was found between the lopinavir concentration in seminal plasma and the time since medication intake (ρ = 0.22, P = 0.45; Spearman's rank) (Fig. 1b). There was a weak relationship between the blood plasma and the seminal plasma concentration (ρ = 0.51, P = 0.07; Spearman's rank). The median ratio of the concentrations of lopinavir in seminal plasma and in blood plasma was only 0.034 (IQR 0.021–0.070) (Fig. 1c). There was no relationship between the lopinavir concentration in blood plasma or seminal plasma and HIV-1-RNA level in blood plasma or in seminal plasma (ρ = 0.11, P = 0.73; Spearman's rank) (Fig. 1a and b) and no relationship between the lopinavir concentration in seminal plasma and HIV-1-RNA level in seminal plasma (ρ = 0.46, P = 0.11; Spearman's rank). We demonstrated that lopinavir has a poor penetration into the seminal plasma, with a median concentration of only 0.23 mg/l (range 0.046–3.9 mg/l), assuming the same percentage protein binding in seminal plasma as in blood plasma (98–99%; Abbott product information). Because of this poor penetration one would expect a poor suppression of the viral replication in semen. However, only four out of the 14 patients had a detectable HIV-1-RNA level in seminal plasma, of which three patients were not yet in a steady state. An explanation for this could be that all patients were on a regimen containing at least one other antiretroviral drug with a good penetration into the seminal plasma (data not shown). It is, however, conceivable that the replication of HIV-1 in the genital tracts of our patients is only partly suppressed by the other drugs of the regimen, usually two nucleoside analolgues. Although most of the patients had an undetectable HIV-1-RNA level in seminal plasma, the median time on lopinavir was only 16 weeks, and it is possible that in time there will be a selection of HIV-1 strains resistant for the other drugs used. There are indications that the selection of resistant HIV-1 strains in the male genital tract can differ from that in blood plasma [14]. If resistant HIV strains migrate to other compartments a patient is at risk of systemic virological failure. Resistant strains in seminal plasma may also lead to the infection of other individuals with resistant strains. A longer follow-up of HIV-1-RNA levels in seminal plasma is necessary to be confident that the selection of resistance mutations is not a risk of regimens with only partial penetration into the male genital tract. Sanjay U. C. Sankatsinga,b Jackie Drosted David Burgerd Rieneke M. E. van Praaga,b Suzanne Jurriaansc Joep M. A. Langea,b,c Jan M. Prinsa