4'-C-methyl-beta-D-ribofuranosyl purine and pyrimidine nucleosides revisited.

In order to evaluate their antiviral properties, a series of 4'-C-methyl-beta-D-ribofuranosyl purine and pyrimidine nucleosides has been prepared. Unfortunately, none of these 4'-branched nucleosides showed any antiviral activity or cytotoxcity when tested against HIV, HBV, and Yellow Fever virus.

Pharmacology of beta-L-thymidine and beta-L-2'-deoxycytidine in HepG2 cells and primary human hepatocytes: relevance to chemotherapeutic efficacy against hepatitis B virus.

beta-L-Thymidine (L-dT) and beta-L-2'-deoxycytidine (L-dC) are potent and highly specific inhibitors of hepatitis B virus (HBV) replication both in vivo and in vitro (50% effective concentrations, 0.19 to 0.24 microM in 2.2.15 cells). The intracellular metabolisms of L-dT and L-dC were investigated in HepG2 cells and primary cultured human hepatocytes. L-dT and L-dC were extensively phosphorylated in both cell types, with the 5'-triphosphate derivative being the predominant metabolite. In HepG2 cells, the 5'-triphosphate levels were 27.7 +/- 12.1 and 72.4 +/- 1.8 pmol/10(6) cells for L-dT and L-dC, respectively. In primary human hepatocytes, the 5'-triphosphate levels were 16.5 +/- 9.8 and 90.1 +/- 36.4 pmol/10(6) cells for L-dT and L-dC, respectively. Furthermore, a choline derivative of L-dCDP was detected at concentrations of 15.8 +/- 1.8 and 25.6 +/- 0.1 pmol/10(6) cells in human hepatocytes and HepG2 cells, respectively. In HepG2 cells exposed to L-dC, the 5'-monophosphate and 5'-triphosphate derivatives of beta-L-2'-deoxyuridine (L-dUMP and L-dUTP, respectively) were also observed, reaching intracellular concentrations of 6.7 +/- 0.4 and 18.2 +/- 1.0 pmol/10(6) cells, respectively. In human hepatocytes, L-dUMP and L-dUTP were detected at concentrations of 5.7 +/- 2.4 and 43.5 +/- 26.8 pmol/10(6) cells, respectively. It is likely that deamination of L-dCMP by deoxycytidylate deaminase leads to the formation of L-dUMP, as the parent compound, L-dC, was not a substrate for deoxycytidine deaminase. The intracellular half-lives of L-dTTP, L-dCTP, and L-dUTP were at least 15 h, with intracellular concentrations of each metabolite remaining above their respective 50% inhibitory concentrations for the woodchuck hepatitis virus DNA polymerase for as long as 24 h after removal of the drug from cell cultures. Exposure of HepG2 cells to L-dT in combination with L-dC led to concentrations of the activated metabolites similar to those achieved with either agent alone. These results suggest that the potent anti-HBV activities of L-dT and L-dC are associated with their extensive phosphorylation.

Symptomatic lactic acidosis in hospitalized antiretroviral-treated patients with human immunodeficiency virus infection: a report of 12 cases.

We retrospectively investigated the clinical and histopathologic features of hospitalized patients infected with human immunodeficiency virus who had symptomatic lactic acidosis syndrome at a university teaching hospital during 1995-2000. Twelve patients were identified, 11 during 1998-2000; of these, 5 died with rapid progression to otherwise unexplained multiple-organ failure. All had extensive prior exposure to nucleoside analog reverse-transcriptase inhibitors (NRTIs). At presentation, the most commonly identified NRTI component of antiretroviral regimens was stavudine plus didanosine. Eleven patients presented with abdominal pain, nausea, and/or emesis. Eight patients had prior acute weight loss (mean [+/-SD], 12+/-5.3 kg). Median venous plasma lactate levels were > or =2-fold greater than the upper limit of normal (2.1 mmol/L). Serum transaminase levels were near normal limits at presentation. Histopathologic studies confirmed hepatic macrovesicular and microvesicular steatosis in 6 patients. Concurrent chemical pancreatitis was identified in 6 patients. The increasing number of cases identified during the study period suggests that physicians better recognize symptomatic lactic acidosis and/or that cumulative NRTI exposure may increase the risk for this syndrome.

Prototype trial design for rapid dose selection of antiretroviral drugs: an example using emtricitabine (Coviracil).

Antiretroviral monotherapy for initial drug characterization risks the selection of resistant virus, yet monotherapy is the only setting where many fundamental properties of a new drug can be reliably determined. Using data on viral replication kinetics and dynamics, we designed an accelerated (14 day) open-label study of single agent emtricitabine (formerly known as FTC)--a nucleoside reverse transcriptase inhibitor--to select a dosing regimen for further therapeutic study. Five regimens (25 mg bd, 100 mg od, 200 mg od, 100 mg bd and 200 mg bd) were evaluated in HIV-1-infected subjects over a 14 day dosing period to determine the optimal dose and pharmacokinetics. Serial blood samples for virological, pharmacokinetic and intracellular FTC-triphosphate measurements were drawn frequently. A dose-response relationship for the antiviral activity of emtricitabine was established, with total daily doses of 200 mg or more producing the greatest median HIV-1 viral load suppression: 1.72-1.92 log10. Based on virological outcomes, dose-response analysis and intracellular triphosphate levels, a once-daily dose of 200 mg was selected for further long-term clinical study. Adverse events possibly related to emtricitabine were unremarkable. The antiviral activity of emtricitabine correlated well with intracellular FTC-triphosphate concentrations. This study design is a safe, useful tool for early dose selection for drugs with potent antiretroviral activity and linear pharmacokinetics.

Antiviral beta-L-nucleosides specific for hepatitis B virus infection.

Three simple, related nucleosides, beta-L-2'-deoxycytidine (LdC), beta-Lthymidine (LdT), and beta-L-2'-deoxyadenosine (LdA), have been discovered to be potent, specific and selective inhibitors of the replication hepatitis B virus (HBV), as well as the closely related duck and woodchuck hepatitis viruses (WHV). Structure-activity relationship analysis indicates that the 3'-OH group of the beta-L-2'-deoxyribose of the beta-L-2'-deoxynucleoside confers specific anti-hepadnavirus activity. The simple nucleosides had no effect on the replication of 15 other RNA and DNA viruses, and did not inhibit human DNA polymerases (alpha, beta and gamma) or compromise mitochondrial function. The nucleosides are efficiently converted intracellularly into active triphosphate metabolites that have a long half-life. Once-daily oral administration of these compounds in the woodchuck efficacy model of chronic HBV infection reduced viral load by as much as 10(8) genome equivalents/ml serum and there was no drug-related toxicity. In addition, a decline in WHV surface antigen (WHsAg) paralleled the decrease in viral load. This class of nucleosides displays an excellent overall safety profile. The first compound, LdT, has already entered clinical trials and LdC, currently being developed as a prodrug, is expected to enter the clinic in the near future. These compounds have the potential for use in combination therapy with the goal of achieving superior viral suppression and diminishing the onset of resistance.

Anti-HBV specific beta-L-2'-deoxynucleosides.

A unique series of simple unnatural L-nucleosides that specifically inhibit hepatitis B virus (HBV) replication has been discovered. These molecules have in common a hydroxyl group in the 3'-position (3'-OH) of the beta-L-2'-deoxyribose sugar that confers antiviral activity specifically against hepadnaviruses. Replacement of the 3'-OH broadens activity to other viruses. Substitution in the base decreases antiviral potency and selectivity. Human DNA polymerases and mitochondrial function are not effected. Plasma viremia is reduced up to 8 logs in a woodchuck model of chronic HBV infection. These investigational drugs, used alone or in combination, are expected to offer new therapeutic options for patients with chronic HBV infection.

Antiviral activity and intracellular metabolism of bis(tButylSATE) phosphotriester of beta-L-2',3'dideoxyadenosine, a potent inhibitor of HIV and HBV replication.

The beta-L-nucleoside analogue beta-L-2',3'-dideoxy adenosine (beta-L-ddA) has been shown to exhibit limited antiviral activities. This was attributed to its rapid catabolism through cleavage of the glycosidic bond and poor phosphorylation to the nucleotide beta-L-2',3'-dideoxyadenosine-5'-mono phosphate (beta-L-ddAMP) (Placidi et al., 2000). However, the nucleotide beta-L-2',3'-dideoxyadenosine-5'-triphosphate (beta-L-ddATP) inhibited the activity of both HIV-1 reverse transcriptase (RT) and viral DNA polymerase isolated from woodchuck hepatitis virus-infected serum (a model of hepatitis B) with an inhibitory concentration (IC50) of 2.0 microM without inhibiting human DNA polymerases alpha, beta, or gamma up to a concentration of 100 microM. These results suggested that prodrugs of beta-L-ddAMP may bypass the poor metabolic activation of beta-L-ddA and lead to more potent and selective antiviral activity. Therefore, the mononucleoside phosphotriester derivative of beta-L-ddAMP incorporating the S-pivaloyl-2-thioethyl (tButylSATE) groups, beta-L-ddAMP-bis(tButylSATE) was synthesized. Beta-L-ddAMP-bis(tButylSATE) inhibited HIV replication in human peripheral blood mononuclear cells (PBMCs) and HBV replication in 2.2.15 cells with effective concentrations (EC50s) of 2 and 80 nM, respectively. Intracellular metabolism of beta-L-ddAMP-bis(tButylSATE) demonstrated that beta-L-ddATP was the predominant intracellular metabolite in PBMC and liver cells. The intracellular half-life of beta-L-ddATP was 5.4 and 9.2 h in HepG2 and PBMCs, respectively. The intracellular concentrations of beta-L-ddATP were maintained above the EC50 for the inhibition of HIV RT and hepatitis B virus (HBV) for as long as 24 h after removal of the drug.

Stereospecific synthesis and biological evaluations of beta-L-pentofuranonucleoside derivatives of 5-fluorouracil and 5-fluorocytosine.

In the search for new chemotherapeutic agents, we have focused our work on the synthesis and the study of several unnatural beta-L-nucleoside analogues. In this paper, we report on the synthesis of beta-L-pentofuranonucleosides (and their 2'-deoxy derivatives) of 5-fluorouracil and their inhibitory effects on the proliferation of several murine and human tumor cells. The corresponding 5-fluorocytosine derivatives were also synthesized and their anti-HIV and anti-HBV activities have been evaluated.

Intravenous infusion of cereport increases uptake and efficacy of acyclovir in herpes simplex virus-infected rat brains.

The outcome of herpes simplex virus (HSV) infections manifesting as encephalitis in healthy or immunocompromised individuals is generally very poor with mortality rates of about 8 to 28% with treatment. The long-term prognosis of survivors is often problematic, posing the need for alternative treatments that may decrease the mortality and morbidity associated with herpes encephalitis. This study addresses one such approach that includes a temporary permeabilization of the blood-brain barrier during treatment with acyclovir (ACV). In these studies we utilized a synthetic bradykinin analog, Cereport (RMP-7), in conjunction with ACV to treat HSV infection of the brain in a rat model. Cereport, infused intravenously via the jugular vein, was shown to increase [(14)C]ACV uptake in both the HSV-1-infected and -uninfected rat brain by approximately two- to threefold, correlating with enhanced efficacy of ACV in various brain compartments. In another series of experiments to determine efficacy, various doses of unlabeled ACV were administered during infusion with RMP-7. The decrease in viral titers in the temporal regions of the brain after 5 days of treatment suggested that this approach enhanced the efficacy of ACV treatment. These data indicated that Cereport infused with ACV enhances both the penetration and efficacy of this drug in the treatment of an experimental HSV-1 infection of the rat brain.

5-(Trifluoromethyl)-beta-l-2'-deoxyuridine, the L-enantiomer of trifluorothymidine: stereospecific synthesis and antiherpetic evaluations.

As a part of our ongoing work on beta-L-nucleoside analogues as potential antiviral drugs, we have synthesized 5-(trifluoromethyl)-beta-L-2'-deoxyuridine (L-TFT), the hitherto unknown L-enantiomer of trifluorothymidine (CF(3)dUrd, TFT). We have also studied the effect of L-TFT on human and herpes simplex virus (HSV) type 1 and 2 thymidine kinases, and human thymidine phosphorylase, as well as its anti-HSV-1 and anti-HSV-2 activities in cell cultures. L-TFT has been found: (i) to inhibit HSV-1 TK with activity comparable to TFT, with no effect on human TK, (ii) to be phosphorylated by the viral enzyme with similar efficiency to TFT, (iii) to be resistant, in contrast to TFT, to hydrolysis by human thymidine phosphorylase. Unfortunately, when evaluated in cell cultures, L-TFT did not show any anti-HSV-1 and anti-HSV-2 activities.

Evaluation of the mutagenic and genotoxic activities of anti-hepatitis B analogs of beta-L-adenosine by the Ames test and the Comet assay.

beta-L-2'-deoxyadenosine (beta-L-dA), beta-L-2',3'-dideoxyadenosine (beta-L-ddA) and its two bis (S-acyl-2-thioethyl; SATE) phosphotriester derivatives, beta-L-2',3'-dideoxyadenosine-5'-monophosphate-bis(MeSATE) and beta-L-2',3'-dideoxyadenosine-5'-monophosphate-bis(tButylSATE) have been previously shown to exhibit potent and selective anti-hepatitis B activity in vitro. None of the four compounds was mutagenic up to 100 microg in the Ames test (microtechnique) using Salmonella typhimurium strains TA 97a, TA 98, TA 100 and TA 102, with and without metabolic activation. In addition, the genotoxicity of beta-LdA and the three other compounds was evaluated in human lymphocytes using the Comet assay, at doses up to 5 microg with or without the addition of a microsomal S9 fraction. None of the four compounds induced DNA strand breakage with and without metabolic activation. In summary, the data clearly demonstrate that the purine nucleoside beta-L-dA, beta-L-ddA and the two prodrugs, beta-L-ddAMP-bis(MeSATE) and beta-L-ddAMP-bis(tButylSATE) are not mutagenic in the Ames test and do not induce DNA damage in human lymphocytes, as assessed by the Comet assay.

NDP kinase reactivity towards 3TC nucleotides.

Nucleoside diphosphate (NDP) kinase is usually considered as the enzyme responsible for the last step of the cellular phosphorylation pathway leading to the synthesis of biologically active triphospho-derivatives of nucleoside analogs used in antiviral therapies and in particular in the treatment of AIDS. NDP kinase lacks specificity for the nucleobase and can use as substrate both ribo- or 2'-deoxyribonucleotides. However, only nucleoside analogs with a sugar moiety in the D-configuration (e.g. 3'-deoxy-3'-azidothymidine (AZT), 2',3'-didehydro-2',3'-dideoxythymidine (d4T)) have so far been analyzed as substrates of NDP kinase. In contrast, beta-L-2',3'-dideoxy-3'-thiacytidine (3TC), also called lamivudine, is a nucleoside analog that is now widely used in AIDS therapy and has a sugar moiety in the L-configuration. Using protein fluorescence to monitor the phosphotransfer between the enzyme and the nucleotide derivative at the presteady state, we have studied the reactivity of 3TC triphosphate and of other L-dideoxynucleotides with NDP kinase. We found that L-dideoxynucleoside triphosphates have a poor affinity for NDP kinase and that the catalytic efficiency of the phosphorylation of L-dideoxyderivatives is very low as compared with their D-enantiomers. We discuss these results using a computer model of 3TC diphosphate bound to the NDP kinase active site. NDP kinase may not seem to be the major enzyme phosphorylating 3TC-DP, in contrast to current opinion.

Indinavir, nevirapine, stavudine, and lamivudine for human immunodeficiency virus-infected, amprenavir-experienced subjects: AIDS Clinical Trials Group protocol 373.

This prospective, multicenter, open-label study was designed to determine the antiretroviral activity and safety of a 4-drug regimen: 1000 mg indinavir every 8 h with 200 mg nevirapine, 40 mg stavudine, and 150 mg lamivudine, each given twice daily in amprenavir-experienced subjects. The primary end points of the study were the human immunodeficiency virus (HIV) RNA level and CD4 cell count responses. Fifty-six subjects were enrolled and were changed from amprenavir-containing regimens to the 4-drug regimen. Overall, at week 48, 33 (59%) of 56 subjects had HIV RNA levels <500 copies/mL (intent-to-treat analysis, where missing values equal > or =500 copies/mL) and CD4 cell counts increased by 94 cells/mm(3) from baseline. Subjects who had previously taken amprenavir combination therapy were more likely to experience virologic failure than those who had taken amprenavir monotherapy (odds ratio, 7.7; P=.0012). In this study, most subjects who had taken amprenavir-based regimens and who changed to a 4-drug regimen achieved subsequent durable virologic suppression.

Antiviral L-nucleosides specific for hepatitis B virus infection.

A unique series of simple "unnatural" nucleosides has been discovered to inhibit hepatitis B virus (HBV) replication. Through structure-activity analysis it was found that the 3'-OH group of the beta-L-2'-deoxyribose of the beta-L-2'-deoxynucleoside confers specific antihepadnavirus activity. The unsubstituted nucleosides beta-L-2'-deoxycytidine, beta-L-thymidine, and beta-L-2'-deoxyadenosine had the most potent, selective, and specific antiviral activity against HBV replication. Human DNA polymerases (alpha, beta, and gamma) and mitochondrial function were not affected. In the woodchuck model of chronic HBV infection, viral load was reduced by as much as 10(8) genome equivalents/ml of serum and there was no drug-related toxicity. In addition, the decline in woodchuck hepatitis virus surface antigen paralleled the decrease in viral load. These investigational drugs, used alone or in combination, are expected to offer new therapeutic options for patients with chronic HBV infection.

Mechanism of action of 1-beta-D-2,6-diaminopurine dioxolane, a prodrug of the human immunodeficiency virus type 1 inhibitor 1-beta-D-dioxolane guanosine.

(-)-beta-D-2,6-Diaminopurine dioxolane (DAPD), is a nucleoside reverse transcriptase (RT) inhibitor with activity against human immunodeficiency virus type 1 (HIV-1). DAPD, which was designed as a water-soluble prodrug, is deaminated by adenosine deaminase to give (-)-beta-D-dioxolane guanine (DXG). By using calf adenosine deaminase a K(m) value of 15 +/- 0.7 microM was determined for DAPD, which was similar to the K(m) value for adenosine. However, the k(cat) for DAPD was 540-fold slower than the k(cat) for adenosine. In CEM cells and peripheral blood mononuclear cells exposed to DAPD or DXG, only the 5'-triphosphate of DXG (DXG-TP) was detected. DXG-TP is a potent alternative substrate inhibitor of HIV-1 RT. Rapid transient kinetic studies show the efficiency of incorporation for DXG-TP to be lower than that measured for the natural substrate, 2'-deoxyguanosine 5'-triphosphate. DXG-TP is a weak inhibitor of human DNA polymerases alpha and beta. Against the large subunit of human DNA polymerase gamma a K(i) value of 4.3 +/- 0.4 microM was determined for DXG-TP. DXG showed little or no cytotoxicity and no mitochondrial toxicity at the concentrations tested.

Simultaneous quantitation of the 5'-triphosphate metabolites of zidovudine, lamivudine, and stavudine in peripheral mononuclear blood cells of HIV infected patients by high-performance liquid chromatography tandem mass spectrometry.

A high-performance liquid chromatography (HPLC) method utilizing triple quadrupole mass spectrometry (MS) detection was developed and validated for the simultaneous measurement of the intracellular nucleoside 5'-triphosphate anabolites of zidovudine (ZDV-TP), lamivudine (3TC-TP), and stavudine (d4T-TP). These compounds were extracted from patient peripheral blood mononuclear cells (PBMCs) which are the sites of HIV replication and drug action. Ion-exchange solid phase extraction (SPE) followed by enzymatic digestion with alkaline phosphatase was utilized to yield the measurable nucleoside forms of the nucleotides. Reversed phase C-18 SPE with addition of a nucleoside internal standard, 3'-azido-2',3'-dideoxyuridine (AzdU) allowed for the indirect measurement of the original 5'-triphosphate concentration by HPLC/MS/MS. Quantitation was performed from calibration curves generated from authentic 5'-triphosphate standards spiked in PBMCs from healthy volunteers. Analytical range for the three 5'-triphosphates was equivalent to 50-45,000 pg. Mean interassay accuracies for 3TC-TP, d4T-TP, and ZDV-TP (n > 90) were 99.4%, 100.1%, and 108.0%, respectively. Mean interassay precisions (%C.V.) for 3TC-TP, d4T-TP, and ZDV-TP (n > 90) were 8.8%, 10.4%, and 8.2%, respectively. Recovery of the extraction method was 79.2%, 83.1%, and 98.3% for 3TC-TP, d4T-TP, and ZDV-TP, respectively. This method can be utilized to measure the intracellular 5'-triphosphate levels in HIV infected patients receiving antiretroviral therapy containing the nucleoside reverse transcriptase inhibitors 3TC, d4T, or ZDV.

Phase I dose escalation pharmacokinetics of O-(chloroacetylcarbamoyl) fumagillol (TNP-470) and its metabolites in AIDS patients with Kaposi's sarcoma.

The pharmacokinetics of TNP-470 and its major metabolites were investigated in AIDS patients enrolled in a phase I dose escalation trial for the treatment of Kaposi's sarcoma. The patients received TNP-470 by 1-h intravenous infusion in dose cohorts of 10, 20, 30, 40, 50 and 70 mg/m2. The parent drug and metabolites, MII and MIV, were measured by high-performance liquid chromatography/mass spectrometry (HPLC/MS) in plasma samples collected during and out to 168 h after the beginning of the infusion. Both metabolites were detected in all patients' plasma, while the parent drug was undetectable at time-points as early as 5 min after the end of infusion for some patients. A large interpatient variability of pharmacokinetic parameters among the dosing cohorts was observed for TNP-470, with a mean (+/- SD) plasma elimination half-life (t1/2) of 0.06 +/- 0.04 h, plasma clearance (CL) of 1487 +/- 1216 l/h and an area under the concentration versus time curve (AUC) of 49.9 +/- 35.8 ng/ml x h. Time to maximum plasma concentration (Tmax) typically occurred before the end of the infusion. The predominant plasma metabolite was MII with a t1/2 of 1.21 +/- 0.43 h, AUC of 1226 +/- 2303 l/h and a Tmax occurring between 5 and 15 min after infusion. The reported active metabolite MIV had a t1/2 of 0.24 +/- 0.13 h, AUC of 24.9 +/- 32.6 ng/ml x h and a Tmax occurring between the midpoint of the infusion and 15 min after infusion. The parent drug was undetectable by HPLC/MS/MS in urine samples collected and pooled between 0-6 and 6-24 h from the beginning of drug administration. Metabolite MIV was present in the 0-6-h urine pool of two patients enrolled in the highest dosing cohorts, equivalent to 0.4% of the administered dose. Metabolite MII was present in all 0-6-h samples analyzed and represented 1.12 +/- 0.9% of the administered dose. Renal clearance (CLR) for MII was 140 +/- 70 ml/h.

Effects of beta-L-3'-azido-3'-deoxythymidine 5'-triphosphate on host and viral DNA polymerases.

We have previously reported that several beta-L-thymidine analogues including beta-L-3'-azido-3'-deoxythymidine (beta-L-AZT), beta-L-3'-fluoro-2',3'-dideoxythymidine (beta-L-FLT) and beta-L-2', 3'-didehydro-2',3'-dideoxythymidine (beta-L-D4T) did not inhibit HIV replication in human peripheral blood mononuclear (PBM) cells whereas their corresponding beta-D-counterparts are known as potent and selective anti-HIV agents [Faraj et al., 1997. Nucleosides and Nucleotides 16, 1287-1290]. In order to gain insight on the lack of antiviral activities of these beta-L-derivatives, in vitro enzymatic steady state studies were conducted in the present study with beta-L-AZT. beta-L-AZT 5'-triphosphate (L-AZTTP) was chemically synthesized and found to moderately inhibit wild-type HIV reverse transcriptase (HIV-1 RT) with a K(i) value of 2 microM; while lacking any inhibitory effect towards human DNA polymerase alpha, beta or gamma. However, the inhibitory effect of L-AZTTP towards HIV-1 RT was very modest (266-fold less potent) when compared to its isomer beta-D-AZT 5'-triphosphate (D-AZTTP) which exhibits a K(i) value of 0.0075 microM and this finding was further confirmed by DNA chain termination assay. These data suggest that the absence of antiviral activity of the parent beta-L-AZT may in part be explained by the poor inhibition of the targeted viral enzyme by L-AZTTP, the active metabolite. Finally, L-AZTTP was found to lack affinity for the mutant RT at position 184 (M184V) demonstrating that this mutation confers resistance not only to beta-L-2',3'-dideoxycytidine analogs as previously reported by our group [Faraj et al., 1994. Antimicrob. Agents Chemother. 38, 2300-2305] but as well as to beta-L-2',3'-dideoxythymidine analogs.

Continued lamivudine versus delavirdine in combination with indinavir and zidovudine or stavudine in lamivudine-experienced patients: results of Adult AIDS Clinical Trials Group protocol 370.

OBJECTIVE: To compare the virologic activity of continued lamivudine (3TC) versus a switch to delavirdine (DLV) when initiating protease inhibitor therapy in nucleoside-experienced patients. DESIGN: Randomized, open-label, multi-center study. SETTING: Adult AIDS clinical trials units. PATIENTS: Protease and non-nucleoside reverse transcriptase inhibitor-naive patients who had received 3TC plus zidovudine (ZDV), stavudine (d4T), or didanosine (ddl) for at least 24 weeks. INTERVENTIONS: Patients with plasma HIV-1 RNA levels > 500 copies/ml who previously received d4T + 3TC or ddI + 3TC were randomized to ZDV + 3TC + indinavir (IDV) or ZDV + DLV + IDV. MAIN OUTCOME MEASURES: Primary endpoints were the proportion of patients with plasma HIV-1 RNA levels < or = 200 copies/ml at 24 weeks, and occurrence of serious adverse events. The proportion of patients with plasma HIV-1 RNA levels < or = 200 copies/ml at week 48 was a secondary endpoint. RESULTS: At week 24, 58% of subjects in the ZDV + 3TC + IDV arm and 73% in the ZDV + DLV + IDV arm had plasma HIV-1 RNA levels < or = 200 copies/ml (P = 0.29). At week 48, plasma HIV-1 RNA levels were < or = 200 copies/ml in 48% and 83%, respectively (P = 0.007). Rash and hyperbilirubinemia occurred more frequently in the DLV arm than in the 3TC arm. Steady-state plasma IDV levels were higher among patients in the DLV arm as compared with the 3TC arm. CONCLUSIONS: Substituting DLV for 3TC when adding IDV improved virologic outcome in nucleoside-experienced patients. This result might be explained, in part, by the positive effect of DLV on IDV pharmacokinetics.

Enhanced penetration of indinavir in cerebrospinal fluid and semen after the addition of low-dose ritonavir.

OBJECTIVE: Penetration of antiretroviral drugs into anatomical HIV-1 reservoirs such as the male genital tract and the central nervous system is important. 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), lamivudine, abacavir, nevirapine and IDV (1000 mg three times daily). When nevirapine 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 cerebrospinal fluid sample were collected at weeks 8, 24, 48 and 72. RESULTS: Addition of RTV increased the median IDV trough concentration in serum 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 cerebrospinal fluid from 39 (n = 12) to 104 (n = 7) ng/ml (P < 0.001). In six patients with samples collected both before and after the addition of RTV, the IDV concentration in seminal plasma increased 8.2 times [95% confidence interval (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 potency 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-glycoprotein-mediated transport by RTV might be an additional mechanism.