Comprehensive longitudinal analysis of hepatitis C virus (HCV)-specific T cell responses during acute HCV infection in the presence of existing HIV-1 infection.

The aim of this study was to study the development of HCV-specific T cell immunity during acute HCV infection in the presence of an existing HIV-1 infection in four HIV-1 infected men having sex with men. A comprehensive analysis of HCV-specific T cell responses was performed at two time points during acute HCV infection using a T cell expansion assay with overlapping peptide pools spanning the entire HCV genome Three patients with (near) normal CD4+ T cell counts (range 400-970 x 10(6)/L) either resolved (n=1) or temporary suppressed HCV RNA. In contrast, one patient with low CD4+ T cell counts (330 x 10(6)/L), had sustained high HCV RNA levels. All four patients had low HCV-specific CD8+ T cell responses, and similar magnitudes of CD4+ T cell responses. Interestingly, individuals with resolved infection or temporary suppression of HCV-RNA had HCV-specific CD4+ T cell responses predominantly against nonstructural (NS) proteins. While the individual with high HCV RNA plasma concentrations had CD4+ T cell responses predominantly directed against Core. Our data show that an acute HCV infection in an HIV-1 infected person can be suppressed in the presence of HCV-specific CD4+ T cell response targeting non-structural proteins. However further research is needed in a larger group of patients to evaluate the role of HIV-1 on HCV-specific T cell responses in relation to outcome of acute HCV infection.

Identification and profiling of circulating metabolites of atazanavir, a HIV protease inhibitor.

Atazanavir is a commonly prescribed protease inhibitor for treatment of HIV-1 infection. Thus far, only limited data are available on the in vivo metabolism of the drug. Three systemic circulating metabolites have been reported, but their chemical structures have not been released publicly. Atazanavir metabolites may contribute to its effectiveness but also to its toxicity and interactions. Thus, there is a need for extensive metabolic profiling of atazanavir. Our goals were to screen and identify previously unknown atazanavir metabolites and to develop a sensitive metabolite profiling method in plasma. Five atazanavir metabolites were detected and identified in patient samples using liquid chromatography coupled to linear ion trap mass spectrometry: one N-dealkylation product (M1), two metabolites resulting from carbamate hydrolysis (M2 and M3), a hydroxylated product (M4), and a keto-metabolite (M5). For sensitive semiquantitative analysis of the metabolites in plasma, the method was transferred to liquid chromatography coupled to triple quadrupole mass spectrometry. In 12 patient samples, all the metabolites could be detected, and possible other potential atazanavir keto-metabolites were found. Atazanavir metabolite levels were positively correlated with atazanavir levels, but interindividual variability was high. The developed atazanavir metabolic screening method can now be used for further clinical pharmacological research with this antiretroviral agent.

Quantification of HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors in peripheral blood mononuclear cell lysate using liquid chromatography coupled with tandem mass spectrometry.

For pharmacokinetic monitoring, measurement of antiretroviral agents in plasma is the gold standard. However, human immunodeficiency virus protease inhibitors (PIs) or non-nucleoside reverse transcriptase inhibitors (NNRTIs) exert their action within the infected cell. Cell-associated concentrations may therefore more adequately reflect therapy outcome. Therefore, for the quantification of nine PIs (amprenavir, atazanavir, darunavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir and tipranavir), 1 active PI metabolite (nelfinavir M8) and 2 NNRTIs (efavirenz and nevirapine) in lysate of peripheral blood mononuclear cells (PBMCs) an assay was developed and validated, using liquid chromatography coupled with tandem mass spectrometry. Analytes were extracted from a PBMC pellet by means of a one-step extraction with 50% methanol containing the internal standards D6-indinavir, D5-saquinavir, 13C6-efavirenz and dibenzepine. Chromatographic separation was performed on a reversed phase C18 column (150mmx2.0mm, particle size 5microm) with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.25mL/min. The analytical run time was 10min. The triple quadrupole mass spectrometer was operated in the positive ion-mode and multiple reaction monitoring was used for drug quantification. The method was validated over a range of 1-500ng/mL in PBMC lysate for all analytes. The method was proven to be specific, accurate, precise and robust. The mean precision and accuracy was less than +/-12% at all concentration levels. Using the developed assay and a previously developed assay for these analytes in plasma, the relationship between plasma and intracellular pharmacokinetics and their relationship with therapy outcome can now be determined.

Tissue expansion for correction of baldness in aplasia cutis congenita.

UNLABELLED: Aplasia cutis is a congenital absence of the skin, usually presenting on the scalp. In 20% of all cases, part of the skull is also absent. A residual area of baldness may still be present some years after surgical or conservative treatment. It is possible to excise the scarred hairless region and cover that area with expanded hair-bearing skin from the rest of the skull. We present three patients who underwent tissue expansion and discuss the indications and pitfalls of this procedure. CONCLUSION: Tissue expansion can be used to cover a residual alopecia defect in young children with aplasia cutis congenita and associated bone abnormalities. The quality of the bone appears to be normal in our three patients. We demonstrate that even in young children with aplasia cutis and an underlying bony defect, tissue expansion is a safe and effective modality as a second stage reconstruction procedure.

Effect of HIV viral load, CD4 cell count and antiretroviral therapy on human papillomavirus prevalence in urine samples of HIV-infected men.

HIV-infected patients are at increased risk for persistent human papillomavirus (HPV) infection, the major cause of anogenital cancer. The present study describes the HPV prevalence in urine samples of 243 HIV-infected men and a control group of 231 men. HPV DNA was amplified by the SPF10 polymerase chain reaction primer set. The overall HPV prevalence in HIV-infected men was 27.5% compared with 12.6% in controls (P < 0.01). Infections with high-risk and multiple HPV genotypes were present in both groups. Differences were not statistically significant. A multivariate logistic regression model showed a decreased HPV prevalence associated with use of a nucleoside and a non-nucleoside reverse transcriptase inhibitor combination (P = 0.03). A trend was observed towards a higher HPV prevalence and a lower CD4 cell count. Further prospective studies are needed to determine the role of HPV DNA testing in urine in future screening programmes for anal cancer in men.

Quantification of etravirine (TMC125) in plasma, dried blood spots and peripheral blood mononuclear cell lysate by liquid chromatography tandem mass spectrometry.

For the quantification of the novel non-nucleoside reverse transcriptase inhibitor etravirine in human plasma, dried blood spots and peripheral blood mononuclear cell (PBMC) lysate, an assay was developed and validated, using liquid chromatography coupled with tandem mass spectrometry. Etravirine was extracted from plasma by means of protein precipitation with a mixture of methanol and acetonitrile using only 50 microL plasma. Extraction from dried blood spots was performed with a one-step extraction with a mixture of methanol, acetonitrile and 0.2M zinc sulphate in water (1:1:2, v/v/v) and extraction from cell lysate was performed in 50% methanol in water. Chromatographic separation was performed on a reversed phase C18 column (150mmx2.0mm, particle size 5microm) with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.25mL/min. (13)C(6)-efavirenz was used as an internal standard. The analytical run time was only 10min. The triple quadrupole mass spectrometer was operated in the positive ion-mode and multiple reaction monitoring was used for drug quantification. The method was validated over a range of 25-5000ng/mL in plasma, 50-10,000ng/mL in dried blood spots and a range of 5-2500ng/mL in PBMC lysate. Accuracies ranged from 89% to 106% in plasma, from 94% to 109% in dried blood spots and from 91% to 105% in PBMC lysate. Precisions at the all concentration levels ranged from 1.9% to 14% in plasma, 4.7% to 20% in dried blood spots and from 3.1% to 11% in PBMC lysate. The bioanalytical assay was successfully incorporated with previously developed assays for the determination of all currently approved PIs and NNRTIs in plasma and dried blood spots and it is now applied for therapeutic drug monitoring and pharmacological research in HIV-infected patients treated with etravirine.

Quantification of the HIV-integrase inhibitor raltegravir and detection of its main metabolite in human plasma, dried blood spots and peripheral blood mononuclear cell lysate by means of high-performance liquid chromatography tandem mass spectrometry.

For the quantification of the HIV-integrase inhibitor raltegravir in human plasma, dried blood spots and peripheral blood mononuclear cell (PBMC) lysate, an assay was developed and validated, using liquid chromatography coupled with tandem mass spectrometry. The assay also allowed detection, but no quantification due to absence of reference substance, of the main metabolite, raltegravir-glucuronide. Raltegravir was extracted from plasma by means of protein precipitation with a mixture of methanol and acetonitrile using only 50microL plasma. Extraction from dried blood spots was performed with a simple one-step extraction with a mixture of methanol, acetonitrile and 0.2M zincsulphate in water (1:1:2, v/v/v) and extraction from cell lysate was performed in 50% methanol in water. Chromatographic separation was performed on a reversed phase C18 column (150mmx2.0mm, particle size 5microm) with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.25mL/min. The analytical run time was 10min. The triple quadrupole mass spectrometer was operated in the positive ion-mode and multiple reaction monitoring was used for drug quantification. The method was validated over a range of 50-10,000ng/mL in plasma and dried blood spots and a range of 1-500ng/mL in PBMC lysate. Dibenzepine was used as the internal standard. The method was proven to be specific, accurate, precise and robust. Accuracies ranged from 104% to 105% in plasma, from 93% to 105% in dried blood spots and from 82% to 113% in PBMC lysate. Precision over the complete concentration range was less than 6%, 11% and 13% in plasma, dried blood spots and PBMC lysate, respectively. The method is now applied for therapeutic drug monitoring and pharmacological research in HIV-infected patients treated with raltegravir.

Quantification of protease inhibitors and non-nucleoside reverse transcriptase inhibitors in dried blood spots by liquid chromatography-triple quadrupole mass spectrometry.

A bioanalytical method for the determination of most commonly prescribed protease inhibitors (atazanavir, darunavir, lopinavir and ritonavir) and non-nucleoside reverse transcriptase inhibitors (efavirenz and nevirapine) was developed and validated according to FDA guidelines. In brief, dried blood spots were punched out of a collection paper with a 0.25 in. diameter punch. The analytes were extracted from the punched-out disc using a mixture of acetonitrile, methanol and 0.2M zinc sulphate in water (1:1:2, v/v/v) containing the internal standards dibenzepine, 13C6-efavirenz and D5-saquinavir. 20 microL of the extract was injected onto the reversed-phase C18 column (150 mm x 2.0 mm) for separation from endogenous compounds and the analytes were quantified using a triple quadrupole mass spectrometer. The analytical run time was only 10 min. Validated concentration ranges covered the ranges encountered in routine clinical practice. The assay was linear over the concentration ranges tested (0.1-20 mg/L for atazanavir, lopinavir, nevirapine and efavirenz and 0.05-10 mg/L for darunavir and ritonavir). Accuracies and inter- and intra-run precisions at all levels ranged from 96.2 to 113.9% and 3.1 to 13.3%, respectively. Analytes in dried blood spots were stable for at least 7 days at 30 degrees C. The method enabled patient-friendly sample collection, easy and cheap sample shipment and non-hospital based sampling for therapeutic drug monitoring and pharmacokinetic studies.

An aeration energy model for an immersed membrane bioreactor.

A simple model for evaluating energy demand arising from aeration of an MBR is presented based on a combination of empirical data for the membrane aeration and biokinetic modelling for the biological aeration. The model assumes that aeration of the membrane provides a proportion of the dissolved oxygen demanded for the biotreatment. The model also assumes, based on literature information sources, a linear relationship between membrane permeability and membrane aeration up to a threshold value, beyond which permeability is unchanged with membrane aeration. The model was benchmarked against two full-scale plant to obtain the most appropriate and conservative value of the slope of the flux:aeration curve and the blower efficiency. Benchmarking in this way produced a match to within 20% of all key process plant operational parameters. The model demonstrated that significant reductions in aeration energy could be obtained through operation at lower flux and reducing the membrane aeration requirement accordingly, so-called "proportional aeration" at lower flows. Similarly, increasing oxygen transfer from membrane aeration would also be expected to decrease energy demand. A sensitivity analysis of some of the key parameters revealed that, of the key operating parameters, loading, SOTE and MLSS concentration remain the most critical in determining energy demand. It is suggested that a key parameter representing membrane aeration in MBRs is the mean in-module air upflow velocity U, since this gives a reasonable representation of the shear applied through membrane aeration. U was found to vary between 0.04 and 0.1m/s across a number of modern large pilot and full-scale plant. An analysis reveals that significant reductions in energy demand are attained through operating at lower MLSS levels and membrane fluxes. Evidence provided from recent controlled pilot trials implies that halving the flux can reduce the aeration is suggested whereby the number of membrane tanks on line and/or the membrane aeration intensity is adjusted according to the flow, and thus flux, so as to reduce the overall aeration energy demand.

Full-scale granular sludge Anammox process.

The start-up of the first full scale Anammox reactor is complete. The reactor shows stable operation, even at loading rates of 10 kg N/m3.d. This performance is the result of the formation of Anammox granules, which have a high density and settling velocities exceeding 100 m/h. With this performance, the Anammox granular sludge technology has been proven on full scale.

Brain natriuretic peptide as a predictor of adverse outcome in patients with pulmonary embolism.

BACKGROUND: Despite effective treatment with anticoagulants, 2% to 7% of patients with pulmonary embolism will die as a result of their disease. METHODS AND RESULTS: We examined in 110 consecutive patients with pulmonary embolism whether plasma brain natriuretic peptide (BNP), a novel marker of (right) ventricular dysfunction, is a predictor of fatal pulmonary embolism. The relationship between BNP concentration measured at presentation and clinical outcome was assessed by comparing the proportion of outcome events among tertiles. Positive and negative predictive values of BNP levels in the highest and lowest tertiles were calculated. The risk of death related to pulmonary embolism if the BNP level is >21.7 pmol/L is 17% (95% CI, 6% to 33%). The negative predictive value for uneventful outcome of a BNP value <21.7 pmol/L is 99% (95% CI, 93% to 100%). CONCLUSIONS: This is the first study to show that plasma BNP levels seem to predict adverse outcome in patients with acute pulmonary embolism.

SHARON process evaluated for improved wastewater treatment plant nitrogen effluent quality.

New stricter nitrogen effluent standards and increasing influent loads require existing wastewater treatment plans (WWTPs) to extend or optimize. At WWTPs with limited aeration capacity, limited denitrification capacity or shortage of aerobic sludge age, implementation of SHARON to improve nitrogen effluent quality can be a solution. SHARON is a compact, sustainable and cost-effective biological process for treatment of nitrogen-rich rejection waters. At WWTP Rotterdam-Dokhaven and WWTP Utrecht a SHARON has been in operation for several years. For both WWTPs the effect of SHARON on the nitrogen effluent quality has been evaluated. WWTP Rotterdam-Dokhaven has limited aeration capacity. By implementation of SHARON, the ammonia load of the effluent was reduced by 50%. WWTP Utrecht had limited denitrification capacity. The implementation of SHARON improved the effluent nitrate load by 40%. The overall TN removal efficiency increased from 65% to over 75% and strict nitrogen effluents standards (TN = 10 mg N/l) could be reached. Through modelling and supported by full scale practice it has been shown that by implementation of SHARON in combination with enhanced influent pre-treatment, the aerobic sludge age can be extended to maintain total nitrogen removal at lower temperatures.

Risk Factors for Sexual Transmission of Hepatitis C Virus Among Human Immunodeficiency Virus-Infected Men Who Have Sex With Men: A Case-Control Study.

Background. Since 2000, incidence of sexually acquired hepatitis C virus (HCV)-infection has increased among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM). To date, few case-control and cohort studies evaluating HCV transmission risk factors were conducted in this population, and most of these studies were initially designed to study HIV-related risk behavior and characteristics. Methods. From 2009 onwards, HIV-infected MSM with acute HCV infection and controls (HIV-monoinfected MSM) were prospectively included in the MOSAIC (MSM Observational Study of Acute Infection with hepatitis C) study at 5 large HIV outpatient clinics in the Netherlands. Written questionnaires were administered, covering sociodemographics, bloodborne risk factors for HCV infection, sexual behavior, and drug use. Clinical data were acquired through linkage with databases from the Dutch HIV Monitoring Foundation. For this study, determinants of HCV acquisition collected at the inclusion visit were analyzed using logistic regression. Results. Two hundred thirteen HIV-infected MSM (82 MSM with acute HCV infection and 131 MSM without) were included with a median age of 45.7 years (interquartile range [IQR], 41.0-52.2). Receptive unprotected anal intercourse (adjusted odds ratio [aOR], 5.01; 95% confidence interval [CI], 1.63-15.4), sharing sex toys (aOR, 3.62; 95% CI, 1.04-12.5), unprotected fisting (aOR, 2.57; 95% CI, 1.02-6.44), injecting drugs (aOR, 15.62; 95% CI, 1.27-192.6), sharing straws when snorting drugs (aOR, 3.40; 95% CI, 1.39-8.32), lower CD4 cell count (aOR, 1.75 per cubic root; 95% CI, 1.19-2.58), and recent diagnosis of ulcerative sexually transmitted infection (aOR, 4.82; 95% CI, 1.60-14.53) had significant effects on HCV acquisition. Conclusions. In this study, both sexual behavior and biological factors appear to independently increase the risk of HCV acquisition among HIV-infected MSM.

Penetration of zidovudine into the cerebrospinal fluid of patients infected with HIV.

OBJECTIVE: To investigate penetration of zidovudine (ZDV) into the cerebrospinal fluid (CSF) of HIV-infected patients for whom a lumbar puncture was indicated. DESIGN: A prospective study. SETTING: General 525-bed hospital with special funding for treatment and research of HIV-infected patients. PATIENTS, PARTICIPANTS: Thirty-nine patients with a medical indication for lumbar puncture who used ZDV chronically were included in this study (50 samples in total). MAIN OUTCOME MEASURE: Determination of ZDV and proteins in CSF and plasma samples. RESULTS: CSF concentrations of ZDV showed little fluctuation 1-8 h after the last ingestion of ZDV. In contrast, plasma levels displayed large variability in this period and decreased exponentially over time. As a result, the CSF/plasma ratio increased linearly over time. No significant relation between the ZDV dose, neither the medical indication for lumbar puncture nor the protein ratio (as a measure for the integrity of the blood-brain barrier), and CSF levels of ZDV was found. The CSF/plasma ratio of ZDV did not give essential information on drug distribution into CSF. CONCLUSIONS: Penetration of ZDV into the CSF appears to be independent of the dose (range, 200-1250 mg daily), which may be an explanation for the efficacy of low doses of ZDV in the prevention and treatment of HIV-related neurological diseases. ZDV levels were at steady-state during the first 6 h after ingestion. The CSF/plasma ratio of ZDV concentrations is not an appropriate marker for drug penetration into CSF.

Appearance of predictors of disease progression in relation to the development of AIDS.

To study the natural history of HIV-1 infection in relation to serological and immunological profiles, 199 asymptomatic HIV-1-antibody (HIV-1-core-antibody)-seropositive and 76 seroconverted homosexual men were followed prospectively for 39 months. AIDS was diagnosed in 38 men. The AIDS attack rate was 20.8% after 39 months. The AIDS attack rate in the HIV-I-core-antibody positives was 12.1, versus 30.1% in the HIV-1-core-antibody negatives (P less than 0.001), and it was 13.3% in the HIV-1-antigen (HIV-1-Ag) negatives versus 53.9% in the HIV-1-Ag positives (P less than 0.001). The AIDS attack rate after 39 months was 10.9% in men with counts greater than or equal to 0.5 x 10(9)/l and 49.9% in those with CD4+ lymphocyte counts less than 0.5 x 10(9)/l. AIDS attack rates after 30 months in the same cohort have been previously reported [1], and were as follows: 6.8% in the core-antibody positives versus 35.7% in the core-antibody negatives. 6.9% in the HIV-1-Ag negatives versus 43.9% in the HIV-1-Ag positives, and 6.1% in those with CD4+ lymphocyte counts greater than or equal to 0.5 versus 51.9% in those with CD4+ lymphocyte counts less than 0.5 x 10(9)/l. The disappearance of core antibody, the appearance of antigen and the occurrence of low CD4+ lymphocyte counts preceded AIDS by a mean (s.d.) of 21.3 (8.9), 17.7 (8.8) and 15.7 (8.9) months, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Once-daily dosing of saquinavir and low-dose ritonavir in HIV-1-infected individuals: a pharmacokinetic pilot study.

OBJECTIVE: To investigate the steady-state pharmacokinetics of a once-daily dosing regimen of saquinavir soft gelatin capsules in combination with a low dose of ritonavir in HIV-1-infected individuals. DESIGN: Open-label, multi-dose, pharmacokinetic pilot study. PATIENTS: Seven HIV-1-infected individuals who were treated with saquinavir hard gelatin capsules 400 mg twice daily + ritonavir liquid formulation 400 mg twice daily were switched to saquinavir soft gelatin formulation 1600 mg once daily in combination with ritonavir liquid formulation 200 mg once daily (day 0). Patients were instructed to ingest saquinavir and ritonavir simultaneously in the morning and with a meal. METHODS: Steady-state pharmacokinetics of saquinavir and ritonavir were assessed during a 24 h dosing interval after 2 weeks of continued therapy (day 14). Plasma saquinavir and ritonavir concentrations were measured using a validated high performance liquid chromatography assay. In addition, plasma HIV-1 RNA, and fasting total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglyceride levels were measured on days 0 and 14. A non-compartmental pharmacokinetic method was used to calculate the area under the plasma concentration versus time curve (AUC[0-24h]), the maximum and trough plasma concentrations (Cmax and Cmin), the time to reach Cmax (Tmax), the elimination half-life (t1/2), the apparent clearance (Cl/F), and the apparent volume of distribution (V/F). RESULTS: Median (range) values of the pharmacokinetic parameters for saquinavir after 2 weeks of treatment were: AUC[0-24h], 19,802h* ng/ml (3720-74,016); Cmax, 2936 ng/ml (573-6848); Cmin, 84 ng/ml (11-854); Tmax, 3.5 h (3.0-4.0), t1/2, 6.8 h (4.6-10.2); Cl/F, 81 l/h (22-430); V/F, 1189 l (215-3086). Ritonavir concentrations were always below the 90% effective concentration of 2100 ng/ml (median Cmax, 1323 ng/ml; range, 692-1528 ng/ml). No significant changes were observed for total serum cholesterol, high-density lipoprotein, and low-density lipoprotein levels between days 0 and 14 (P > or = 0.24). In six out of seven patients the fasting serum triglyceride levels were lower 2 weeks after the treatment switch (median decrease was 32%, P = 0.03). No significant changes in plasma HIV-1 RNA concentrations were observed between days 0 and 14. The regimen was generally well tolerated. CONCLUSIONS: This pharmacokinetic study indicates that the combination of 1600 mg of saquinavir (soft gelatin capsules) and 200 mg of ritonavir (liquid formulation) in a once-daily dosing regimen generally results in therapeutic plasma concentrations of saquinavir. Due to the large interindividual variation in saquinavir exposure, the monitoring of saquinavir concentrations in plasma is warranted. These pharmacokinetic findings rationalize the further clinical evaluation of once-daily dosing of this combination of protease inhibitors.

Trends in mortality among AIDS patients in Amsterdam, 1982-1988.

In this study we evaluated the survival of 515 AIDS patients diagnosed in Amsterdam between 1982 and 1988 and followed-up until April 1990. Non-resident patients survived for a shorter period than resident patients (median survival time 10 versus 16 months). Residents had a 1-, 2- and 3-year survival of 56.1, 33.0 and 17.2%, respectively. Heterosexual intravenous drug users tended to have a better survival than homosexual men, although this was not significant. The survival time was longer for AIDS patients less than 30 years of age at diagnosis and varied for the different clinical manifestations leading to AIDS diagnosis. We calculated the 1- and 2-year survival probability by year of diagnosis for patients initially presenting with a Pneumocystis carinii pneumonia (PCP). The 1-year survival improved greatly in 1986 and continued to rise in the following years. The 2-year survival was similar in 1986 and 1987 (26.8 versus 28.2%) but increased in 1988 (38.9%). We conclude that besides better clinical experience and diagnostic methods, this improvement in prognosis could be explained by the start of secondary prophylaxis for PCP in 1985 and the introduction of zidovudine therapy in 1987.

The steady-state plasma pharmacokinetics of indinavir alone and in combination with a low dose of ritonavir in twice daily dosing regimens in HIV-1-infected individuals.

OBJECTIVE: To explore the steady-state plasma pharmacokinetics of indinavir in twice daily dosing regimens with and without the co-administration of 100 mg ritonavir. DESIGN: Observational pharmacokinetic study. PATIENTS: HIV-1-infected individuals who use indinavir alone (1200 mg twice daily, n = 6), or the combination of 100 mg ritonavir twice daily plus either 800 mg (n = 6), or 1200 mg indinavir twice daily (n = 2). METHODS: Steady-state pharmacokinetics of indinavir and ritonavir were assessed by drawing 12 blood samples during an 8-h period after ingestion of the medication. RESULTS: Significant differences were observed for indinavir pharmacokinetics between the dosing regimens indinavir 1200 mg twice daily alone and indinavir/ ritonavir 800/100 mg twice daily with respect to the mean trough concentration (0.21 and 0.99 microg/ml, respectively, P = 0.002), the mean maximum concentration (13.79 and 8.74 microg/ml, respectively, P = 0.028), and for the mean plasma elimination half-life (1.6 and 3.2 h, respectively, P = 0.001). The combination indinavir/ritonavir 1200/100 mg twice daily led to very high exposure to indinavir and was not well tolerated. However, the combination indinavir/ritonavir 800/100 mg twice daily was well tolerated and resulted in therapeutic concentrations of indinavir with improved trough concentrations and similar maximum concentrations as observed with the licensed dosage of 800 mg three times daily. CONCLUSION: Combination of indinavir and 100 mg ritonavir in twice daily dosing regimens significantly affects the pharmacokinetic profile of indinavir. The results of this observational study provide a pharmacologic basis for the combination of indinavir (800 mg) and ritonavir (100 mg) in twice daily dosing regimens.

Zidovudine twice daily in asymptomatic subjects with HIV infection and a high risk of progression to AIDS: a randomized, double-blind placebo-controlled study. The European-Australian Collaborative Group (Study 017)

OBJECTIVE: To evaluate the efficacy of zidovudine given twice daily in subjects with asymptomatic HIV-1 infection and a high risk of progression to AIDS. DESIGN: Randomized, double-blind placebo-controlled trial. SETTING: Multicentre study in five European countries and Australia. PATIENTS: Asymptomatic subjects (n = 329) with CD4 cell counts between 200 and 400 x 10(6)/l, or if > 400 x 10(6)/l, subjects with HIV p24 antigenaemia (> 10 pg/ml). INTERVENTION: Patients were randomly assigned to receive zidovudine 500 mg or placebo twice daily for 104 weeks, following a 250 mg four times daily dose regimen for the first 4 weeks. MAIN OUTCOME MEASURES: The primary end-point was the development of AIDS or severe AIDS-related complex (ARC). Before unblinding the study other end-points were defined: the development of Centers for Disease Control and Prevention (CDC) group IV disease (AIDS, severe ARC and other CDC stage IV disease) and the development of symptomatic HIV disease (AIDS, severe ARC, other CDC stage IV disease and minor HIV disease). Changes in CD4+ cell counts, p24 antigenaemia and toxicity were also reviewed. RESULTS: Median treatment duration was 57 weeks for the placebo and 60 weeks for the zidovudine group, respectively. Progression to AIDS or severe ARC occurred in 17 placebo and 12 zidovudine recipients (log-rank P = 0.26). However, in the first of the 2 study years the rate of progression to AIDS or severe ARC was significantly higher in the placebo than in the zidovudine group. Zidovudine delayed progression to symptomatic HIV disease (P = 0.01); a trend in a delay in progression to CDC stage IV disease was observed (P = 0.08). Zidovudine recipients maintained CD4+ cell counts at or above baseline levels for longer than placebo recipients (P = 0.04). HIV p24-antigen levels decreased in the zidovudine group and returned to pretreatment levels by week 36. Substantial toxicity was not observed. CONCLUSIONS: Zidovudine twice daily is effective in delaying progression to symptomatic HIV disease in high-risk, asymptomatic HIV-infected subjects. Modified definitions of clinical end-points may be useful for evaluating Phase III trials in comparable patient groups in the light of changes in the definition of AIDS and the increasing use of primary prophylaxis against opportunistic infections.

Pharmacokinetic variability of zidovudine in HIV-infected individuals: subgroup analysis and drug interactions.

OBJECTIVE: To investigate determinants of inter- and intraindividual variability of zidovudine (ZDV) pharmacokinetics in HIV-infected patients. DESIGN: A prospective study in a general 525-bed hospital with special funding for treatment and research of HIV-infected patients. METHODS: Serial blood samples were collected from 68 HIV-infected individuals providing a total of 95 pharmacokinetic curves. ZDV was measured with high-performance liquid chromatography and radioimmunoassay. Pharmacokinetic parameters were calculated by non-compartmental analysis. Patient characteristics were investigated by multivariate analysis for an influence on ZDV pharmacokinetics. RESULTS: Apparent ZDV clearance was significantly lower in patients with a lower body weight, in women, and in patients with a more advanced stage of HIV disease. Co-administration of methadone with ZDV resulted in higher plasma concentrations of ZDV, while rifampin and ganciclovir increased apparent ZDV clearance. Age, the duration of ZDV use, CD4+ cell count, creatinine clearance, elevated serum liver enzyme levels, and the use of 11 other co-administered medications were not independently related to apparent ZDV clearance. CONCLUSIONS: The pharmacokinetic profile of ZDV in several subpopulations has been evaluated, as well as the observation of possible drug-drug interactions between ZDV and 14 different drugs or groups of drugs. These data suggest that patient-individualized antiretroviral therapy may be appropriate once pharmacokinetic-pharmacodynamic relationships have been established.