Repositioning HIV protease inhibitors and nucleos(t)ide RNA polymerase inhibitors for the treatment of SARS-CoV-2 infection and COVID-19.

AIMS: SARS-CoV-2 is a single-stranded RNA virus which is part of the ß-coronavirus family (like SARS 2002 and MERS 2012). The high prevalence of hospitalization and mortality, in addition to the lack of vaccines and therapeutics, forces scientists and clinicians around the world to evaluate new therapeutic options. One strategy is the repositioning of already known drugs, which were approved drugs for other indications. SUBJECT AND METHOD: SARS-CoV-2 entry inhibitors, RNA polymerase inhibitors, and protease inhibitors seem to be valuable targets of research. At the beginning of the pandemic, the ClinicalTrials.gov webpage listed n=479 clinical trials related to the antiviral treatment of SARS-CoV-2 (01.04.2020, "SARS-CoV-2," "COVID-19," "antivirals," "therapy"), of which n=376 are still accessible online in January 2021 (10.01.2021). Taking into account further studies not listed in the CTG webpage, this narrative review appraises HIV protease inhibitors and nucleos(t)ide RNA polymerase inhibitors as promising candidates for the treatment of COVID-19. RESULTS: Lopinavir/ritonavir, darunavir/cobicistat, remdesivir, tenofovir-disoproxilfumarate, favipriravir, and sofosbuvir are evaluated in clinical studies worldwide. Study designs show a high variability and results often are contradictory. Remdesivir is the drug, which is deployed in nearly 70% of the reviewed clinical trials, followed by lopinavir/ritonavir, favipiravir, ribavirine, and sofosbuvir. DISCUSSION: This review discusses the pharmacological/clinical background and questions the rationale and study design of clinical trials with already approved HIV protease inhibitors and nucleos(t)ide RNA polymerase inhibitors which are repositioned during the SARS-CoV-2 pandemic worldwide. Proposals are made for future study design and drug repositioning of approved antiretroviral compounds.

Similar maximum systemic but not local cyclooxygenase-2 inhibition by 50 mg lumiracoxib and 90 mg etoricoxib: a randomized controlled trial in healthy subjects.

PURPOSE: Once daily doses of 100-400 mg lumiracoxib have been proposed to inhibit local prostaglandin synthesis longer than systemic prostaglandin synthesis due to local accumulation in inflamed, acidic tissue. Lower, less toxic doses, however, might still achieve the clinical goal and merit further contemplation. METHODS: In a randomized, double-blind, placebo-controlled, three-way cross-over study, 18 healthy men received, with an interval of 24 h, two oral doses of 50 mg lumiracoxib or for comparison, 90 mg etoricoxib, for which local tissue accumulation has not been claimed as therapeutic component. Systemic and local drug concentrations, assessed by means of subcutaneous in-vivo microdialysis, were related to COX-2 inhibiting effects, quantified as inhibition of prostaglandin ex-vivo production in whole blood as well as local tissue prostaglandin (PG) concentrations. RESULTS: Twenty-four hours after the first dose, only etoricoxib was detectable in plasma and inhibited PGE2 production. In contrast, after the second dose, systemic PGE2 concentrations were significantly reduced by both coxibs, indicating similar maximum systemic effects of the selected doses. The local COX-2 inhibition by etoricoxib was most pronounced for PGD2. To the contrary, no indication was given of local inhibition of PG production by lumiracoxib at the dose tested. CONCLUSIONS: Doses of 50 mg lumiracoxib and 90 mg etoricoxib produced similar maximum inhibition of systemic COX-2 function whereas 50 mg lumiracoxib was ineffective in producing local COX-2 inhibition. At a 50 mg dosage, lumiracoxib does not provide peripheral effects that outlast its systemic actions in therapies of rheumatic diseases such as osteoarthritis.

Lopinavir/ritonavir pharmacokinetics, efficacy, and safety in HIV and hepatitis B or C coinfected adults without symptoms of hepatic impairment.

OBJECTIVE: Lopinavir/ritonavir plus nucleoside reverse transcriptase inhibitors is one standard antiretroviral therapy regimen, both in patients with HIV alone and coinfected with hepatitis B or C. Our objective was to investigate whether hepatitis coinfection without clinical signs of hepatic impairment is a cofactor altering lopinavir pharmacokinetics and influencing therapy outcome. METHODS: Steady-state 12-hour pharmacokinetic profiles of lopinavir/ritonavir were assessed in patients with (group 1, n = 20) or without (group 2, n = 36) hepatitis coinfection, taking lopinavir/ritonavir 400/100 mg twice a day plus nucleoside reverse transcriptase inhibitors, measured by means of high-performance liquid chromatography-tandem mass spectrometry. Demographic (sex, age, weight), pharmacological (formulation, comedication), clinical, and virological/immunologic parameters (HIV-RNA PCR, CD4(+) cell count) were compared between the groups and included in regression analyses for correlations with lopinavir pharmacokinetic parameters (C(min), C(max), AUC, CL, and t(1/2)) and viral load evolution over 48 weeks on therapy. Patient pairs were matched 1:2 for the parameters sex, age, weight, ethnicity, and drug formulation. RESULTS: None of the hepatitis-related cofactors (aspartate aminotransferase, alanine aminotransferase, γGT, HBe Ag, HBsAg, HCV-RNA PCR, HCV-therapy) had an influence on lopinavir pharmacokinetics in this group of patients. Lopinavir C(min) (P = 0.039) and area under the curve (P = 0.038) and ritonavir C(max) (P = 0.049) were significantly enhanced in hepatitis-coinfected patients, but correlated only with drug formulation (ie, soft gel capsule or Meltrex tablet formulation, multivariate regression analysis, P = 0.001), not hepatitis coinfection. CONCLUSIONS: Despite moderately enhanced lopinavir/ritonavir plasma concentrations, regular therapeutic drug monitoring is not to be considered in hepatitis-coinfected patients without hepatic impairment. Antiviral efficacy is comparable between both groups, a less-pronounced CD4(+) cell increase in hepatitis-coinfected patients is in line with previously published data.

Impact of HIV-1 replication on immunological evolution during long-term dual-boosted protease inhibitor therapy.

To explore CD4-cell and viral evolution in relation to different levels of HIV-1 replication, as observed during protease inhibitor (PI)-based antiretroviral therapy. Adult HIV-1 infected cohort patients, receiving historical salvage therapy with daily doses of saquinavir (2,000 mg), ritonavir (200 mg) and either lopinavir (800 mg) or atazanavir (300 mg) for >36 weeks were retrospectively analysed for highest detectable viral load up to week 96 and assigned to groups according to the viral load level: always <50 copies/ml (1), 50-199 copies/ml (2), 200-499 copies/ml (3) and ≥500 copies/ml (4). A total of 126 patients were evaluated; at baseline, median CD4-cell count was 204/mm(3), HIV-1 RNA was 5.13 Log10-copies/ml and duration of prior HIV-1 infection was 11.7 years. Patients were assigned by 43, 30, 7 and 20 % to groups 1-4. Median observation time was 136 weeks (range: 38-304); at weeks 48/96, the CD4-cell gains for groups 1-4 were +88/+209, +209/+349, +67/+300 and +114.5/+ 128, respectively. After fitting data in a linear fixed effect model, ascending CD4 slopes were continuously increasing for group 1, similarly for 2 and clearly decreasing for 3-4 (p = 0.0006). Of 25 individuals from group 4, patient number with major IAS-USA protease mutations increased from 5 to 10 before and after failing PI therapy, whereas minor mutations remained stable (n = 18). On double-boosted PI therapy, CD4-cell increases through week 96 were similar for patients at always undetectable or with detection of low viral load. Viral detection >200 copies/ml was associated with decreasing CD4-cell slopes and emergence of major mutations, supporting this as benchmark for virological failure definition on PI therapy.

Immune response after two doses of the novel split virion, adjuvanted pandemic H1N1 influenza A vaccine in HIV-1-infected patients.

BACKGROUND: To determine the rate of seroconversion after 2 doses of a novel split virion, inactivated, adjuvanted pandemic H1N1 influenza vaccine (A/California/7/2009) in human immunodeficiency virus type 1 (HIV-1)-infected patients (ClinicalTrials.gov NCT01017172). METHODS: Diagnostic study of adult HIV-1-infected patients scheduled for H1N1 influenza A vaccination. Blood samples where taken before and 21 days after the first dose and 21 days after the second dose of the vaccine. Antibody (AB) titers were determined by hemagglutination inhibition assay. Seroconversion was defined by either an AB titer ≤ 1:10 before and ≥ 1:40 after or ≥ 1:10 before and a ≥ 4-fold increase in AB titer 21 days after vaccination. RESULTS: One hundred thirty-five patients received 2 doses of the H1N1 vaccine and were analyzed. The rate of seroconversion was 68.2% (95% confidence interval, 59.6-75.9) after the first dose and 91.9% (95% confidence interval, 85.9-95.9) after the second dose. Patients who did not seroconvert had a lower mean nadir CD4 cell count (± standard deviation; 81 ± 99 vs 190 ± 148 cells/µL; P = .006), had a longer duration of HIV infection (± standard deviation; 13.1 ± 5.9 vs 8.8 ± 6.8 years; P = .04), and were more likely to have an AB titer ≥ 1:40 before vaccination (4% vs 55%; P < .001) when compared with patients with seroconversion. No other differences were found between the 2 groups, including AIDS status, highly active antiretroviral therapy status, HIV RNA - polymerase chain reaction load <50 copies/mL, CD4 cell count, sex, body mass index, and chronic hepatitis. CONCLUSION: Among HIV-infected patients, the rate of seroconversion after the first dose of an adjuvanted H1N1 influenza A vaccine was 68% and increased to 92% after a second doses.

Sequential population pharmacokinetic modeling of lopinavir and ritonavir in healthy volunteers and assessment of different dosing strategies.

Nonlinear mixed-effects modeling was applied to explore the relationship between lopinavir and ritonavir concentrations over 72 h following drug cessation and also to assess other lopinavir and ritonavir dosing strategies compared to the standard 400-mg-100-mg twice-daily dose. Data from 16 healthy volunteers were included. Possible covariates influencing lopinavir and ritonavir pharmacokinetics were also assessed. Data were modeled first separately and then together by using individually predicted ritonavir pharmacokinetic parameters in the final lopinavir model. The model was evaluated by means of a visual predictive check and external validation. A maximum-effect model in which ritonavir inhibited the elimination of lopinavir best described the relationship between ritonavir concentrations and lopinavir clearance (CL/F). A ritonavir concentration of 0.06 mg/liter was associated with a 50% maximum inhibition of the lopinavir CL/F. The population prediction of the lopinavir CL/F in the absence of ritonavir was 21.6 liters/h (relative standard error, 14.0%), and the apparent volume of distribution and absorption rate constant were 55.3 liters (relative standard error, 10.2%) and 0.57 h(-1) (relative standard error, 0.39%), respectively. Overall, 92% and 94% of the observed concentrations were encompassed by the 95% prediction intervals for lopinavir and ritonavir, respectively, which is indicative of an adequate model. Predictions of concentrations from an external data set (HIV infected) (n = 12) satisfied predictive performance criteria. Simulated lopinavir exposures at lopinavir-ritonavir doses of 200 mg-150 mg and 200 mg-50 mg twice daily were 38% and 65% lower, respectively, than that of the standard dose. The model allows a better understanding of the interaction between lopinavir and ritonavir and may allow a better prediction of lopinavir concentrations and assessments of different dosing strategies.

Evaluation of Platelet Activation by HIV Protease Inhibitors - The HIV-PLA II Study.

BACKGROUND: In the past, protease inhibitors (PIs) and the reverse transcriptase inhibitor abacavir were identified increasing the risk for thromboembolic complications and cardiovascular events (CVE) of HIV infected patients taking a combination antiretroviral therapy (cART). Results of the previous HIV-PLA I-study lead to the assumption that platelet activation could play a substantial role in increasing CVE risks. METHODS: The open label, monocentric HIV-PLA II-study investigated HIV-1-infected, therapy-naïve adults (n=45) starting with cART, consisting either of boosted PI (atazanavir, n= 6, darunavir, n=11), NNRTI (efavirenz, n=14) or integrase inhibitor (raltegravir, n=14), each plus tenofovir/emtricitabine co-medication. Main exclusion criteria were tobacco smoking, the intake of NSAIDs or abacavir or past CVE. Platelet adhesive molecule p-selectin (CD62P) and FITC anti-human Integrin α-IIb/Integrin ß-3 (CD41/CD61) antibody (PAC-1) binding, monocyte CD11b/monocyte-associated CD41 expression and the endogenous thrombin potential (ETP) were assessed ex vivo-in vitro at baseline, weeks 4, 12 and 24. Therapy regimens were blinded to the investigators for laboratory and statistical analyses. RESULTS: CD11b and ETP showed no significant changes or differences between all study groups. In contrast, the mean + SD mean fluorescence units (MFI) of CD62P and PAC-1 increased significantly in patients taking PI, indicating an enhanced potential for thrombocyte activation and aggregation. CONCLUSION: CD62P expression, detecting the ɑ-platelet degranulation of pro-inflammatory and pro-thrombotic factors and adhesive proteins, and PAC-1 expression, representing a marker for conformation changes of the GIIb/IIIa receptor, increased significantly in patients taking HIV protease inhibitors. The findings of this study revealed a yet unknown pathway of platelet activation, possibly contributing to the increased risk for CVE under HIV protease inhibitor containing cART. CLINICAL TRIAL REGISTRATION NO: DRKS00000288.

Daily dosing of tacrolimus in patients treated with HIV-1 therapy containing a ritonavir-boosted protease inhibitor or raltegravir.

OBJECTIVES: The number of HIV-infected patients receiving orthotopic liver transplantation (OLTX) is increasing. One major challenge is the severe drug-drug interactions between immunosuppressive drugs such as tacrolimus and ritonavir-boosted HIV-1 protease inhibitors (PIs). The introduction of raltegravir, which is not metabolized by the cytochrome system, may allow concomitant treatment without dose adaptation. PATIENTS AND METHODS: We conducted a retrospective analysis of HIV-1-infected patients receiving tacrolimus concomitantly with different HIV therapies, including 12 h pharmacokinetic assessment of drug levels. RESULTS: Three OLTX patients received a ritonavir-boosted PI therapy when tacrolimus was added at very low doses of 0.06, 0.03 and 0.08 mg daily. Median tacrolimus blood levels were 6.6, 3.0 and 7.9 ng/mL over a follow-up period of 8, 22 and 33 months, respectively. In two other patients (one after OLTX and one with Crohn's disease), a raltegravir-based HIV therapy was started while patients received 1 or 2 mg of tacrolimus twice daily. No tacrolimus dose adjustment was necessary and drug levels remained unchanged. CONCLUSIONS: Decreasing the dose of tacrolimus to 0.03-0.08 mg daily in patients with concomitant boosted PI therapy resulted in stable tacrolimus blood levels without alteration of PI drug levels. Concomitant use of raltegravir and tacrolimus revealed no clinically relevant drug interaction.

Pharmacokinetic analysis of human plasma-derived pasteurized C1-inhibitor concentrate in adults and children with hereditary angioedema: a prospective study.

BACKGROUND: Hereditary angioedema (HAE) is a rare and potentially life-threatening disease presenting with acute edema of subcutaneous tissues and/or mucous membranes. Patients with HAE have abnormally low or dysfunctional C1-inhibitor (C1-INH). Preventing the progression of acute attacks is the main goal of C1-INH replacement therapy; knowledge of the C1-INH concentrate half-life is of crucial importance. This pharmacokinetic study was conducted to investigate the pharmacokinetics of pasteurized human plasma-derived C1-INH concentrate (pC1-INH). STUDY DESIGN AND METHODS: This was a prospective, single-center study of six children and 34 adults with an established diagnosis of HAE. On-demand treatment with pC1-INH was administered to all children, whereas adults received either pC1-INH on-demand treatment or individual replacement therapy (IRT). Functional C1-INH plasma levels were fitted to a single-compartment model with nonlinear regression, and the area under the curve was standardized to a dose equivalent of 15 U/kg body weight of pC1-INH concentrate. RESULTS: The median half-life of functional C1-INH plasma levels in pediatric patients receiving on-demand therapy was 32.9 hours (mean, 31.5 hr). In adults, the median half-lives of functional C1-INH plasma levels after on-demand therapy were 39.1 hours (mean, 47.8 hr) and 30.9 hours (mean 33.3 hr) for patients on IRT. The median times to achieve maximum plasma activity after administration were 0.6 hour for children, 1.0 hour for adults receiving on-demand treatment, and 0.5 hour for adults on IRT. CONCLUSIONS: pC1-INH concentrate has a long median terminal elimination half-life and rapidly reaches maximum plasma concentrations. This rapid onset of clinical efficacy is essential in patients suffering from HAE.

Higher pain scores, similar opioid doses and side effects associated with antipyretic analgesics in specialised tertiary pain care.

PURPOSE: To evaluate whether non-opioid antipyretic analgesics are associated with lower pain scores, opioid doses and side effects in pain patients in tertiary care. METHODS: In a cross-sectional observational study, data from 519 Caucasians (197 men, 322 women; mean age 55.6 ± 15 years) who had undertaken pain therapy for various causes for 77.5 ± 90.8 months, obtained in three separate study centres, was analysed for actual 24-h pain scores, daily opioid doses and the occurrence of side effects. RESULTS: Of the 519 patients, 352 received opioids and 260 antipyretic analgesics, from whom 154 received both classes and 304 only either class. The administration of non-opioid antipyretic analgesics was associated with higher average pain scores (4.6 ± 2.5 vs 3.9 ± 2.6; P = 0.01), tendentially higher average oral morphine equivalent doses (121.8 ± 162.2 vs 146.7 ± 242.4 mg/d; P = 0.25) and a similar incidence of side effects (P = 0.21). These results were correspondingly seen when analysing the three study centres separately as independent cohorts. CONCLUSIONS: With the caution advised for cross-sectional data, the results dispute a clinical benefit of non-opioid antipyretic analgesics for most chronic pain patients in tertiary care and draw attention towards prospectively re-evaluating the utility of non-opioid antipyretic analgesics in tertiary pain care in a randomised placebo controlled trial.

Atazanavir plasma concentrations are impaired in HIV-1-infected adults simultaneously taking a methadone oral solution in a once-daily observed therapy setting.

OBJECTIVE: The human immundeficiency virus (HIV) protease inhibitor atazanavir is often used in once-daily observed therapy of methadone substituted former opiate drug users. We performed a matched-pairs analysis on 24 patients (12 men/women) taking atazanavir/ritonavir 300/100 mg daily plus reverse transcriptase inhibitors, with (n = 12) or without (n = 12) methadone co-administration. METHODS: Twenty-four-hour pharmacokinetic profiles of atazanavir/ritonavir were assessed at steady-state and measured by liquid chromatography-tandem mass spectrometry. The geometric mean (GM, t test) minimum and maximum plasma drug concentrations (C(min), C(max)), area under the concentration-time curve (AUC), and total clearance (CL(total)) were compared between the groups of pairs, which were matched for age, sex, weight, and ethnicity. RESULTS: The GM [90% confidence interval (CI)] of the atazanavir C(min), C(max), and AUC of patients taking the methadone oral solution at doses of 20-175 mg/day simultaneously with antiretroviral therapy were impaired compared to patients not taking methadone oral solution: C(min) = 315 (range 197-448) vs. 519 (279-793) ng/mL [GM ratio (GMR) = 0.61, p = 0.229]; C(max) = 1714 (1238-2262) vs. 3190 (2412-4076) ng/mL (GMR = 0.54, p = 0.018); AUC = 21,987 (15,870-29,327) vs. 35,572 (26,211-46,728) ng h/mL (GMR = 0.62, p = 0.074). Methadone dose, which is proportional to the amount of methadone oral solution (10 mg/mL), was significantly correlated to atazanavir C(max) (r (2) = 0.40, p = 0.001) and AUC (r (2) = 0.32, p = 0.006). Ritonavir pharmacokinetics was similar between the groups with C(min), C(max), and AUC GMR of 1.01, 0.80, and 0.96, respectively. CONCLUSION: The partial decrease in atazanavir plasma concentrations in patients concomitantly taking racemic methadone oral solution in this daily observed therapy setting deserves further attention, and therapeutic drug monitoring should be considered.

Cytochrome P450 3A inhibition by atazanavir and ritonavir, but not demography or drug formulation, influences saquinavir population pharmacokinetics in human immunodeficiency virus type 1-infected adults.

Inadequate concentrations of the human immunodeficiency virus (HIV) protease inhibitor saquinavir jeopardize individual therapy success or produce side effects despite treatment according to the current guidelines. We performed a population pharmacokinetic analysis with NONMEM and determined that the steady-state pharmacokinetics of saquinavir in 136 HIV type 1-infected adults was modulated by a decrease in saquinavir CL following coadministration of the cytochrome P450 3A inhibitors ritonavir and atazanavir. In contrast, age, sex, weight, pregnancy, and the pharmaceutical formulation exerted only minor, nonsignificant effects.

Decrease of atazanavir and lopinavir plasma concentrations in a boosted double human immunodeficiency virus protease inhibitor salvage regimen.

The human immunodeficiency virus protease inhibitor combination of atazanavir (ATV)-lopinavir-ritonavir was reported to exhibit a mutual pharmacoenhancement of plasma lopinavir and ATV concentrations which may be beneficial for salvage patients. We identified 17 patients in our pharmacokinetic database taking this combination and found conflicting results. Plasma concentrations of both ATV and lopinavir were modestly, although not significantly, decreased when the drugs were coadministered. Therefore, patients should be selected carefully for this regimen and frequent clinical and therapeutic drug monitoring is strongly advised.

Pharmacokinetics, safety and efficacy of saquinavir/ ritonavir 1,000/100 mg twice daily as HIV type-1 therapy and transmission prophylaxis in pregnancy.

BACKGROUND: A saquinavir/ritonavir-containing regimen is one option for the prevention of mother-to-child transmission of HIV during pregnancy. We evaluated the pharmacokinetics, efficacy and safety of saquinavir/ritonavir 1,000/100 mg twice daily plus nucleos(t)ide reverse transcriptase inhibitors in 13 women during late pregnancy and compared the results to those of 15 non-pregnant women. METHODS: Protease inhibitor plasma concentration profiles were assessed at 12 h using a standardized therapeutic drug monitoring procedure and measured by LC-MS/MS. Minimum and maximum concentrations (C(min) and C(max)), area under the plasma concentration-time curve (AUC(0-12 h)), and total clearance (CL(total)) were compared between the groups and correlated to demographic, physiological and clinical cofactors. Antiviral and immunological efficacy and safety were investigated. RESULTS: The geometric means (90% confidence interval [CI]) for saquinavir C(min), C(max) and AUC(0-2 h) of pregnant versus non-pregnant women were 572 (437-717) versus 765 (485-1,052, P = 0.064) ng/ml, 2,168 (1,594-2,807) versus 3,344 (2,429-4,350; P = 0.045) ng/ml and 15,512 (11,657-19,943) versus 24,027 (17,454-31,548, P = 0.029) ng x h/ml. The geometric means (90% CI) for ritonavir C(min), C(max) and AUC(0+12 h) were 190 (148-234) versus 310 (240-381, P = 0.011) ng/ml, 781 (580-999) versus 1,552 (1,127-2,007, P = 0.004) ng/ml and 5,576 (4,303-7,006) versus 10,528 (8,131-13,177, P = 0.003) ng x h/ml. Age, weight, saquinavir dose per weight and body mass index differed significantly; saquinavir C(min) and AUC(0-12 h) were correlated with ritonavir C(min) and saquinavir dose per weight. After a mean of 11 weeks treatment, 12 of 13 pregnant women had a viral load < 400 copies/ml, which was similar to the results of non-pregnant women. CONCLUSIONS: Although saquinavir plasma concentrations were significantly lower in pregnant women compared with non-pregnant women, all pregnant women displayed a saquinavir AUC(0-12 h) > 10,000 ng x h/ml, 92.3% had a viral load < 400 copies/ml at birth. Saquinavir was well tolerated by the mothers and all newborn children were HIV type-1 negative at 18 months of age.

Significant effects of tipranavir on platelet aggregation and thromboxane B2 formation in vitro and in vivo.

OBJECTIVES: In the past, bleeding events have been described for patients with haemophilia taking HIV-1 protease inhibitors. Recently, the FDA published a warning concerning intracranial haemorrhage in patients taking the HIV-1 protease inhibitor tipranavir co-administered with ritonavir. METHODS: We investigated (i) platelet aggregation in vivo in HIV-1-infected adult patients (n = 5) immediately before and 2 and 4 h after dosing of tipranavir/ritonavir 500/200 mg. To further characterize the effects, we then evaluated (ii) platelet aggregation and (iii) thromboxane B2 (TxB2) formation (ELISA) with increasing tipranavir concentrations (TPV(conc)) in vitro of up to 100,000 ng/mL. Platelet aggregation was stimulated either with 2 microM ADP (ADP) or 10 mg/L collagen (COL). TPV(conc) were measured with validated EPI-LC-MS/MS. Intraindividual comparisons of values at time points and TPV(conc), respectively, were carried out with repeated samples ANOVA. RESULTS: Platelet aggregation (mean, maximal light transmission A(max)) was significantly decreased in patients 4 h post-dose in collagen- (from 79.8% to 57.1%; P < 0.001) and in ADP-stimulated (from 58.5% to 54.0%; not significant) samples at a median (range) TPV(conc) of 62 500 ng/mL (22,990-67,500). These results could be reproduced in vitro at TPV(conc) 50,000 ng/mL (A(max)ADP/A(max)COL = 20.7/36.9%; P = 0.003/<0.001) and 100 000 ng/mL (A(max)ADP/A(max)COL = 14.5/17.1%; P < 0.001/<0.001). Median (range) TxB2 concentrations were reduced (P = 0.07) from 327 ng/mL (187-500) at baseline to 265 ng/mL (152-428) at 5000 ng/mL and were significantly reduced (P < 0.001) to 187 ng/mL (81-362) at a TPV(conc) of 50,000 ng/mL, respectively. CONCLUSIONS: Five HIV-1-infected patients on tipranavir-containing highly active antiretroviral therapy presented marked decreases in platelet aggregation. In vitro these effects were reproduced and decreased TxB2 formation was also demonstrated. Inhibition of platelet aggregation while receiving tipranavir treatment might contribute to increased risk of bleeding.

The steady-state pharmacokinetics of atazanavir/ritonavir in HIV-1-infected adult outpatients is not affected by gender-related co-factors.

OBJECTIVES: Pharmacokinetic differences, contributing to drug-related side effects, between men and women have been reported for HIV protease inhibitors. As only limited and inconclusive data on ritonavir-boosted atazanavir are available, we evaluated the respective steady-state pharmacokinetics in 48 male and 26 female HIV-1-infected adults receiving atazanavir/ritonavir 300/100 mg once-daily as part of their antiretroviral therapy. METHODS: Pharmacokinetic profiles (24 h) of atazanavir/ritonavir were assessed and measured by HPLC/tandem mass spectrometry. Geometric mean (GM; ANOVA) of minimum and maximum plasma drug concentrations (C(min) and C(max)), area under the concentration-time curve (AUC) and total clearance (CL(total)) were compared between the sexes and correlated to demographic (age, gender and ethnicity), physiological (weight and body mass index) and clinical (CD4+ cell count, HIV-RNA, co-medication and hepatitis serology) co-factors. RESULTS: The GM of the atazanavir AUC, C(max) and C(min) of men versus women were 32 643 versus 36 232 ng.h/mL [GM ratio (GMR) = 1.11, P = 0.435], 2802 versus 3211 ng/mL (GMR = 1.15, P = 0.305) and 398 versus 470 ng/mL (GMR = 1.18, P = 0.406), respectively. Although weight (80.6 versus 63.9 kg, P = 0.001) and body weight-adjusted atazanavir dose (3.84 versus 4.60 mg/kg, P = 0.013) were different between the sexes, no significant correlation to atazanavir pharmacokinetics was observed. A linear regression analysis detected significant correlations of atazanavir C(min) with ritonavir AUC (P < 0.001) and the co-administration of methadone oral solution (P = 0.032), and inverse correlations with the time since the first HIV infection diagnosis (P = 0.003) and the number of previous antiretroviral treatments (P = 0.022). CONCLUSIONS: Atazanavir/ritonavir steady-state pharmacokinetics was comparable in men and women, despite gender-related significant differences in atazanavir dose/body weight. The administration of atazanavir/ritonavir is pharmacokinetically safe; 95% of all trough samples were above the recommended plasma concentration of 150 ng/mL.

Platelet-leucocyte adhesion markers before and after the initiation of antiretroviral therapy with HIV protease inhibitors.

INTRODUCTION: Thromboembolic complications under antiretroviral therapy (ART) have been described in the past. In particular, the influence of protease inhibitors (PIs) on platelet activation and coagulation is currently under discussion. METHODS: HIV-1-infected, PI-naive adults (n = 18) were investigated before and 4 weeks after the start of the ART, consisting either of boosted PI regimens (n = 13) plus reverse transcriptase inhibitors (RTIs) or a double PI regimen (n = 5) without RTI co-medication. Administered PIs were saquinavir (n = 15), lopinavir (n = 4), fosamprenavir (n = 2) and atazanavir (n = 2). Platelet CD62P, CD40L (%+ cells) and PAC-1 binding [mean fluorescence intensity (MFI)] as well as monocyte CD11b (MFI) and monocyte-associated CD41 (%+ cells and MFI) expression were assessed by flow cytometry with or without platelet stimulation. To investigate the influence of platelets on coagulation, the endogenous thrombin potential (ETP) [render fluorescence units (RFI)] was determined. RESULTS: CD62P, PAC-1 binding and CD11b expression remained unchanged. In contrast, the mean+/-SD MFI of CD40L (from 18.2+/-9.0 to 25.5+/-10.4, P = 0.038) and CD41 (from 446.1+/-213.8 to 605.0+/-183.8, P = 0.010) as markers for increased platelet-leucocyte interaction increased significantly. The collagen-induced ETP time-to-peak was altered significantly from 23.8+/-11.4 to 17.0+/-4.2 min (P = 0.028), although the ETP RFI peak showed no evidence for increased procoagulatory capacity (47.1+/-18.6 to 57.3+/-19.9, P = 0.085). CONCLUSIONS: Effects of the evaluated PI HIV therapy on platelet function assessed under field conditions seem to be minor, not affecting all investigated parameters. We found no evidence for increased platelet activation under PI-containing ART. However, CD41 as a marker for increased platelet-leucocyte interaction and CD40L, which can contribute to atherosclerosis, increased significantly.

Predictive factors for response to a boosted dual HIV-protease inhibitor therapy with saquinavir and lopinavir in extensively pre-treated patients.

OBJECTIVE: To evaluate predictive factors for therapy outcome of a boosted double-protease inhibitor (PI) regimen in 58 extensively pre-treated patients with HIV. METHODS: Patients received lopinavir/ritonavir 400/100 mg and saquinavir 1,000 mg twice daily without reverse transcriptase inhibitors (RTI). The primary outcome parameter was HIV RNA < 400 copies/ml at week 48, secondary parameters were HIV-1 RNA and CD4+ T-cell count changes from baseline to week 48. Pharmacokinetics, genotypic resistance and clinical and individual parameters were correlated with the clinical outcome in regression analyses. Covariates for the analyses were minimum plasma concentration (C(min)), maximum plasma concentration, area under the concentration versus time curve, half-life and clearance of lopinavir and saquinavir, the genotypic inhibitory quotients (GIQ) of archived (GI6(arch)) and baseline PI resistance mutations, previously taken antiretrovirals, archived and baseline viral resistance mutations, baseline HIV-1 RNA and CD4+ T-cell count. RESULTS: The analyses detected correlations between the primary outcome parameter and several factors: baseline CD4+ T-cell count (P = 0.001); absence of mutations at V82T/A/F/I/S plus 154M/V/L (P = 0.002) or K20M/R (P = 0.010); and lopinavir C(min)GIQ(arch) (P = 0.046). This regression model had a predictability of 97.0% for response to therapy. Covariates for the decrease of HIV-1 RNA from baseline to week 48 were baseline HIV-1 RNA (P < 0.001), lopinavir C(min)GIQ(arch) (P = 0.013), presence/absence of mutations at V82T/A/F/I/S or 184A/V plus L10I/R/V/F, 154M/V/L or L63P (P = 0.018), and previously taken antiretrovirals (P = 0.034). CONCLUSIONS: Baseline HIV-1 RNA < 5.0 log10 and CD4+ T-cell count > 200 cells/microl, lopinavir C(min)GIQ(arch) > 2,000 ng/ml and the absence of viral resistance mutations at V82T/A/F/I/S and 154M/V/L are highly predictive for therapeutic success of a regimen of saquinavir/lopinavir/ ritonavir without RTI in a heterogenic cohort of patients with an extensive pre-treatment history and highly variable pharmacokinetics.

Effects of the oral, direct factor xa inhibitor rivaroxaban on platelet-induced thrombin generation and prothrombinase activity.

Rivaroxaban (BAY 59-7939) is an oral, direct factor Xa inhibitor in advanced development. This study was undertaken to investigate its effects on thrombin generation. In this placebo-controlled, randomized, crossover study, 12 healthy subjects received rivaroxaban (single 5- or 30-mg dose) or placebo. Thrombin generation was investigated by measuring the endogenous thrombin potential and prothrombinase-induced clotting time. Maximal effect of rivaroxaban was observed 2 hours after drug administration: prothrombinase-induced clotting time was prolonged 1.8 and 2.3 times baseline after rivaroxaban 5 and 30 mg, respectively. Collagen-induced endogenous thrombin potential was reduced by approximately 80% and approximately 90% compared with baseline after rivaroxaban 5 and 30 mg, respectively, and tissue factor-induced endogenous thrombin potential was reduced by approximately 40% (5 mg) and approximately 65% (30 mg), respectively. Thrombin generation remained inhibited for 24 hours. There was a close correlation between plasma concentration of rivaroxaban and prolongation of prothrombinase-induced clotting time and reduction in endogenous thrombin potential. Rivaroxaban strongly inhibits platelet-induced thrombin generation, after activation of either platelets or the coagulation pathway, even in the presence of minimal factor Xa inhibition in plasma.

Tenofovir comedication does not impair the steady-state pharmacokinetics of ritonavir-boosted atazanavir in HIV-1-infected adults.

OBJECTIVE: Our objective was to evaluate the steady-state pharmacokinetics of ritonavir-boosted atazanavir when coadministered with tenofovir in HIV-1-infected adult patients. DESIGN: Forty adult HIV-1-infected patients received either atazanavir/ritonavir 300/100 mg once daily and nucleoside reverse transcriptase inhibitors with (n = 20) or without (n = 20) tenofovir-disoproxil fumarate (tenofovir-DF) 300 mg once daily. Twenty-four-hour pharmacokinetics were assessed after at least 2 weeks of therapy according to a standardised therapeutic drug monitoring protocol. METHODS: Atazanavir/ritonavir plasma concentrations were measured by liquid chromatography tandem mass spectrometry, and the geometric means of minimum and maximum concentrations (C(min), C(max)), the area under the time-concentration curve (AUC), half-life (t(1/2)) and total clearance (CL(tot)) were subject to a matched pairs-analysis. Patients' pairs were matched for gender, ethnicity, weight and Center for Disease Control and Prevention (CDC) status. RESULTS: The respective geometric means (90% CI) for atazanavir C(min), C(max) and AUC with tenfovir vs. without tenofovir were 405 (314-523) vs. 417 (304-572) ng/ml, 3,022 (2,493-3,664) vs. 2,817 (2,341-3,390) ng/ml and 34,822 (29,315-41,363) vs. 32,101 (26,206-39,321) ng x h/ml showing no significant differences between the groups. Atazanavir plasma concentrations measured at week 5 of therapy or later were lower than in the first 4 weeks (T-test for C(max), p = .080; AUC, p = .050 and CL(tot), p = .051). CONCLUSIONS: The coadministration of tenofovir-DF did not impair the plasma concentrations of ritonavir-boosted atazanavir in a pharmacokinetic analysis of patient pairs matched for gender, ethnicity, weight and CDC status.