To Determine if There Are Pharmacokinetic Interactions at Plasma or Intracellular Level Between Nucleosides and Tenofovir

Study Overview
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Brief Summary
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The purpose of this study is to evaluate if there are pharmacokinetic interactions between the NRTI 3TC and ABV, and the TDF nucleotide. For this purpose, the intracellular and plasma levels of 3TC and ABV will be compared in patients given these nucleosides with TDF and 30 days after the interruption of the TDF.

Detailed Description
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There is clear evidence of pharmacokinetic interaction between ddI+TDF. However, the interaction between TDF and other NRTIs, mainly at intracellular level, has not been so well studied. Since all the NRTIs are anabolized at intracellular level by numerous kinases, and are transported by passive carrier systems, the interaction may be between TDF and other NRTIs. This study aims to investigate the pharmacokinetic interactions between the TDF and the nucleosides abacavir (ABV) and lamivudine (3TC) at plasma and intracellular level. With this objective, intracellular and plasma levels will be analysed in a group of patients that receive the combinations 3TC +TDF, ABV+TDF and 3TC+ABV+TDF together with lopinavir/rtv or nevirapine. Subsequently, in a second phase of the study, in the group of patients given ABV and/or 3TC + TDF + lopinavir/rtv, the pharmacokinetic determinations will be repeated after a 4-week interruption of the TDF .

Official Title
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Determination of Plasma and Intracellular Levels of Nucleoside Reverse Transcriptase Inhibitors (NRTI) and of Nucleotide Analog Tenofovir Disoproxil Fumarate (TDF) in Patients Treated With Abacavir and/or Lamivudine Given With or Without TDF.

Conditions
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HIV

Intervention / Treatment
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* Drug: Patients in treatment with 3TC + TDF + LPV/rtv, stop tenofovir during 4 weeks
* Drug: Patients in treatment with ABV + TDF + LPV/rtv, stop tenofovir during 4 weeks
* Drug: Patients in treatment with 3TC + ABV + TDF+ LPV/rtv, stop TDF during 4 weeks


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: HIV+ patients aged above 18 years. Undetectable HIV viral load in the last determination Patients capable of correct compliance according to clinical criteria. Patients on triple HAART therapy for the previous 3 months including 3TC and/or ABV and TDF, with a PI (Lopinavir/ritonavir) or an NNRTI (Nevirapine) Women may not be of fertile age (defined as at least one year from menopause or undergoing any surgical sterilisation technique), or must undertake to use a barrier contraceptive method during the study. Ability to provide informed consent. Exclusion Criteria: Incorrect therapeutic compliance over the four weeks before the beginning of the study. Interruption or withdrawal from therapy during follow-up. Concomitant treatment with any drug which according to the clinician's criterion may interact with the investigational antiretrovirals, such as other antiretrovirals. Triple HAART therapy including Nevirapine (for phase II) Documented or suspected resistance to ABV, 3TC or lopinavir/rtv (for phase II).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Phase I: 3TC + TDF + NVP or LPV/rtv Phase II: patients on treatment with LPV/rtv, stop TDF during 4 weeks: 3TC + LPV/rtv | Drug: Patients in treatment with 3TC + TDF + LPV/rtv, stop tenofovir during 4 weeks<br>* 3TC (300 mg/24 h, 1 tablet/24 h) + Lopinavir/ritonavir (400 mg/12 h, 3 tablets/12 h)<br>* Other names: Kaletra;|
| Experimental: 2<br>Phase I: ABV + TDF + NVP or LPV/rtv Phase II: patients on treatment with LPV/rtv, stop TDF during 4 weeks: ABV + LPV/rtv | Drug: Patients in treatment with ABV + TDF + LPV/rtv, stop tenofovir during 4 weeks<br>* ABV (300 mg/12 h, 1 tablet/12 h)+ Lopinavir/ritonavir (400 mg/12 h, 3 tablets/12 h)<br>* Other names: Kaletra;|
| Experimental: 3<br>Phase I: 3TC + ABV + TDF + NVP or LPV/rtv Phase II: patients on treatment with LPV/rtv, stop TDF during 4 weeks: 3TC + ABV + LPV/rtv | Drug: Patients in treatment with 3TC + ABV + TDF+ LPV/rtv, stop TDF during 4 weeks<br>* 3TC (300 mg/24 h, 1 tablet/24 h)+ ABV (300 mg/12 h, 1 tablet/12 h)+ Lopinavir/ritonavir (400 mg/12 h, 3 tablets/12 h).<br>* Other names: Kaletra;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The primary endpoint will be the variation between the intracellular levels of 3TC and ABC before and after the interruption of the treatment with TDF |  | At baseline and week 4. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Variations between the plasma levels of 3TC and ABC before and after interruption of the treatment with TDF. |  | at baseline and week 4 | 
| Correlation between the intracellular and plasma levels of 3TC, ABC and TDF. |  | at baseline and week 4 | 
| Changes in the intracellular levels of TDF following the withdrawal of the drug. |  | At week 4. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Intracellular concentrations, Plasma concentration, Abacavir, Tenofovir, Lamivudine (3TC), Pharmacokinetic interactions