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Objective: To assess the safety of 2 intermittent treatment strategies compared with continuous therapy for patients with virologic suppression on highly active antiretroviral therapy (HAART) at baseline., Design: Seventy-four nucleoside reverse transcriptase inhibitor (NRTI) and protease inhibitor (PI) pretreated patients with an HIV RNA level <50 copies at screening were randomized to continuous treatment, CD4-guided treatment, or week-on-week-off treatment with 2 NRTIs plus 1600 mg/100 mg of saquinavir/ritonavir once daily. At week 96 (end of the randomized phase of the study), all patients were given continuous HAART for 12 weeks to week 108. Primary outcomes were the proportion of patients with a CD4 count >350 cells/microL and HIV RNA level <400 copies/mL at week 108., Methods: Patients were followed up every 12 weeks for CD4 count, HIV RNA level, and clinical and laboratory toxicities. In the CD4-guided arm, treatment was stopped and restarted using a CD4 count threshold (above or below 350 cells/microL or reduction of 30%)., Results: Seventy-four patients were enrolled with a median CD4 count of 644 cells/microL before the structured treatment interruption (STI). The week-on-week-off arm (n=26) was discontinued at week 72 because of high rates (46%) of HIV RNA rebound above 50 copies/mL. In the continuous arm, 25 (100%) of 25 patients and 24 (96%) of 25 patients had an HIV RNA level <400 copies/mL and <50 copies/mL, respectively, at week 108, and 96% had a CD4 count above 350 cells/microL, with a median CD4 count of 661 cells/microL. Patients in the CD4-guided arm had a significantly lower median CD4 count (489 cells/microL) than the patients in the continuous arm (P=0.03), but all had a CD4 count above 350 cells/microL and 1 had a new HIV-related illness. At week 108, 21 (91%) of 23 patients and 13 (57%) of 23 patients had an HIV RNA level <400 copies/mL and <50 copies/mL, respectively. Those who did not achieve an HIV RNA level <50 copies/mL had a higher HIV RNA load before retreatment, and 4 of 5 patients subsequently achieved viral suppression after an additional 12 weeks of HAART (week 120). Therefore, 17 (94%) of 18 evaluable CD4-guided arm patients achieved viral suppression after retreatment. Antiretroviral (ARV) side effects were similar in all arms. CD4-guided treatment had a 54% ARV cost savings., Conclusions: This pilot study suggests that CD4-guided HAART is a well-tolerated and cost-saving treatment strategy for patients with high pre-ARV and pre-STI CD4 counts. Week-on-week-off treatment had a high virologic failure rate and was discontinued. The HIV RNA suppression rate was similar in patients treated with continuous HAART and in those retreated with 12 to 24 weeks of HAART after CD4-guided therapy.

Objective: To study the pharmacokinetics of indinavir/ ritonavir 400/100 mg twice daily in antiretroviral-naive patients at Srinagarind Hospital in Khon Kaen, Thailand., Methods: This was a steady-state, open-label pharmacokinetic study of 19 patients. A 12 h pharmacokinetic curve was recorded after an overnight fast. Plasma levels of indinavir and ritonavir were determined by a validated HPLC method. Virological failure was defined according to the most recent US Department of Health and Human Services guidelines as a viral load above 400 copies/ml at week 24., Results: Median baseline values for CD4 and viral load were 13cells/mm3 and 167000 copies/ml, respectively. The median (interquartile ranges) for indinavir AUC, Cmax and Cmin were 18.1 (15.3-23.8) mg/l x h, 4.1 (3.6-4.8) mg/l and 0.17 (0.12-0.30) mg/l, respectively. These values represent 37%, 39% and 24% of the AUC, Cmax and Cmin values found, respectively, for the indinavir/ritonavir 800/100 mg dose in HIV-1-infected Thai patients. Short-term virological response was satisfactory. There were three subjects with an indinavir Cmin. below the target value of 0.10 mg/l, of whom one had virological failure (33%). Among the other 16 subjects with an indinavir Cmin above 0.10 mg/l, there was also one virological failure (6%) (P=0.30)., Conclusions: Indinavir exposure in this reduced-dose regimen of 400 mg with 100 mg ritonavir twice daily was more than dose-proportionally lower than previously observed with the indinavir/ritonavir 800/100 mg twice daily regimen. Therapeutic Cmin levels of indinavir were achieved in >80% of the subjects and short-term virological response was satisfactory in this cohort of patients starting highly active antiretroviral therapy at an advanced disease stage with high baseline viral loads.

Objectives: To describe the pharmacokinetics and pharmacodynamics of indinavir with or without low-dose ritonavir in human immunodeficiency virus (HIV)-infected Thai patients., Patients and Methods: Thirty-six HIV-1-infected patients who participated in HIV-NAT 005 study gave informed consent to record a pharmacokinetic curve 4 weeks after starting a regimen containing either indinavir 800 mg every 8 h (n = 19) or indinavir 800 mg + ritonavir 100 mg every 12 h (n = 17). Indinavir plasma concentrations were measured by HPLC. Pharmacokinetic parameters were calculated by non-compartmental methods., Results: The median (interquartile range; IQR) body weight of the 36 patients (11 females and 25 males) was 60 (54-72) kg. Median and IQR values for indinavir AUC, Cmax and Cmin were 20.9 (13.1-27.0) mg x h/L, 8.1 (6.6-9.4) mg/L and 0.13 (0.09-0.27) mg/L, respectively, for indinavir 800 mg every 8 h, and 49.2 (42.5-60.4) mg x h/L, 10.6 (8.5-13.2) mg/L and 0.68 (0.43-0.77) mg/L, respectively, for indinavir 800 mg + ritonavir 100 mg every 12 h. These values are not largely different from values found in Caucasian patients, with the exception of relatively high peak levels of indinavir in Thai subjects. Cut-off values for optimal virological efficacy were an indinavir Cmin of 0.10 and 0.25 mg/L for the every 8 h and the every 12 h regimen, respectively; patients with an indinavir AUC greater than 30 (every 8 h regimen) or 60 (every 12 h regimen) mg x h/L were at increased risk of developing nephrotoxicity., Conclusions: Indinavir pharmacokinetics and pharmacodynamics in Thai HIV-1-infected patients are similar to those described in Caucasian patients, despite an overall lower body weight in this population

Background: Qualitative HIV-1 proviral DNA PCR tests have three main diagnostic applications. These include direct detection of viral sequences in the pre-seroconversion window period which may be positive up to 8 days prior to the development of HIV specific antibodies; resolution of indeterminate HIV serological tests and in the diagnosis of neonates born to seropositive mothers where maternal antibodies may be detectable for up to 15 months past partum., Methods: A total of three serial specimens from a single patient following symptomatic primary HIV-1 infection were assessed by commercially available serological assays for antibodies to HIV and HIV-1 antigen and nucleic acid amplification assays for proviral DNA (Amplicor HIV-1 test, Roche Molecular Systems, CA, USA) and RNA (HIV MONITOR ver1.5, Roche Molecular Systems) according to manufacturers recommendations. A subsequent modified PCR protocol for HIV proviral DNA was performed which included modified primers (SK145/SKCC1B) and altered thermal cycling parameters., Results: We describe a case of HIV infection acquired in Thailand by heterosexual transmission, where a commercially available HIV proviral DNA PCR assay remained negative despite a typical evolving serological profile consistent with seroconversion., Conclusion: These data support the use of HIV DNA PCR tests only as a second line supplemental test to licensed standard HIV diagnostic testing strategies, and should be used with care in cases where non-B subtype infection is a possibility., (Copyright 2002 Elsevier Science B.V.)

Unlabelled: A total of 72 HIV-1 infected Thai patients treated with didanosine (ddI) or stavudine (d4T) plus ddI at the time of interim analysis were analyzed. Sixty patients (83%) carried subtype E documented by HIV-1 V3 serotyping. HIV-1 RNA levels were measured using three commercial viral load assays. At baseline (n = 57), Quantiplex 2.0 and NucliSens 2.0 showed mean log10 HIV-1 RNA of 0.7 log10 or 5 fold lower than Amplicor 1.5 (mean 4.29 versus 5.0 log10, respectively, p < 0.001). At week 20 of treatment (n = 29), HIV-1 RNA levels were detected in 55.2%, 31%, and 33.5% of subjects tested by Amplicor 1.5, Quantiplex 2.0, and NucliSens 2.0, respectively., In Conclusion: plasma HIV-1 RNA analyses showed comparable values with Quantiplex 2.0 and NucliSens 2.0 assays. In contrast, Amplicor 1.5 resulted in approximately 5 folds higher HIV-1 RNA levels and a 25% higher rate of detection of plasma HIV-1 RNA as compared to the other two assays. As the current goal of therapy is to suppress plasma viral load below the detection limit of the assays, the significant differences between the assays may influence antiretroviral efficacy evaluation and management.