Steroids Pharmacokinetics and the Response to Prednisone Therapy in Giant Cell Arteritis

Study Overview
=================
Brief Summary
-----------------
The factors underlying the large interindividual variability in response to glucocorticoids in Giant Cell Arteritis are poorly understood. The investigators hypothesize that a part of this variability is related to pharmacokinetic factors determined by genetic polymorphism: hepatic clearance involving cytochromes P450 of the subfamily 3A (CYP3A) and drug efflux leukocyte conditioned by P-glycoprotein involved in multidrug resistance drugs (ABCB1). The investigators have designed a multicentric prospective pharmacokinetical and pharmacogenetic cohort study to assess the link between prednisolone clearance and the relapse risk in giant cell arteritis.

Official Title
-----------------
Study the Link Between Steroids Pharmacokinetics and the Response to Prednisone Therapy in Giant Cell Arteritis

Conditions
-----------------
Giant Cell Arteritis

Intervention / Treatment
-----------------
* Drug: Prednisone therapy and pharmacokinetic


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Diagnosis of GCA, meeting at least 3 of the following 5 American College of Rheumatology (ACR) criteria for the diagnosis of GCA: At least 50 years of age at disease onset New onset or new type of localized pain in the head Temporal artery abnormality (i.e., temporal artery tenderness to palpation or decreased pulsation unrelated to arteriosclerosis of cervical arteries) ESR of greater than 40 mm in the first hour by the Westergren method Temporal artery biopsy showing vasculitis characterized by a predominance of mononuclear cell infiltration or granulomatous inflammation, usually with multinucleated giant cells Corticoid treatment since less than 14 days Signed informed consent Affiliation to the social security system Exclusion Criteria: Dementia Predictable non observance Neoplasia since less than 5 years

Ages Eligible for Study
-----------------
Minimum Age: 50 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Intervention/Treatment |
| --- |
|Drug: Prednisone therapy and pharmacokinetic|Prednisone therapy delivered in accordance with a 10 to 18 month pre-defined schedule. Pharmacokinetic and pharmacogenetic tests at 14 or 28 days. Monthly visit for the first 6 month, then every 8 weeks months thereafter for the remainder of the study with standard biologic monitoring , physical exam and medical and medication history .Also, participants will be asked to complete several questionnaires to assess quality of life and observance to therapy. Participants may have additional study visits if a disease flare or disease-related complications occur during the study.|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| oral clearance of prednisolone |  | 2 to 4 weeks after begining prednisolone treatment | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Giant Cell Arteritis, prednisone, pharmacokinetics