title: Doxycycline assay hair samples for testing long-term compliance treatment.
abstract: OBJECTIVE
  Many patients undergoing long-term doxycycline treatment do not regularly take their treatment because of photosensitivity. Our objective was to create an assay for determining doxycycline levels and to use hair samples for monitoring the compliance over a longer period of time.
  
  
  METHODS
  We tested sera and hair samples from patients treated with doxycycline by a suitable ultra-high performance liquid chromatography (UHPLC) based assay.
  
  
  RESULTS
  We estimated that the speed of hair growth is roughly 1.25 cm per month and we were able to determine doxycycline levels over a 6-month period. We tested 14 patients treated with doxycycline and we found similar levels of doxycycline in the serum and the hair samples representing the last 4 months. Linear regression analysis revealed that the level of doxycycline in the serum remained stable over time (p = 0.7) but the level of doxycycline in the hair decreased significantly over time (p = 0.03) indicating a degradation of this molecule in the hair. We detected two patients who did not have antibiotic in the hair, indicating a lack of compliance that was also confirmed by interview.
  
  
  CONCLUSIONS
  Hair samples can be used to test long-term compliance in patients to explain failures or relapses.
authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes: URMITE CNRS-IRD 198 UMR 6236, Aix Marseille Université, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France.
authors: Emmanouil
authors: E
authors: Angelakis
authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes: URMITE CNRS-IRD 198 UMR 6236, Aix Marseille Université, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France.
authors: Nicholas
authors: N
authors: Armstrong
authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes: URMITE CNRS-IRD 198 UMR 6236, Aix Marseille Université, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France.
authors: Claude
authors: C
authors: Nappez
authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes: URMITE CNRS-IRD 198 UMR 6236, Aix Marseille Université, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France.
authors: Magalie
authors: M
authors: Richez
authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes: URMITE CNRS-IRD 198 UMR 6236, Aix Marseille Université, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France.
authors: Eric
authors: E
authors: Chabriere
authors: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes: URMITE CNRS-IRD 198 UMR 6236, Aix Marseille Université, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France. Electronic address: Didier.raoult@gmail.com.
authors: Didier
authors: D
authors: Raoult
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000097:blood / Q000627:therapeutic use; D002853:Chromatography, Liquid; D004318:Doxycycline / Q000032:analysis* / Q000097:blood / Q000627:therapeutic use; D005260:Female; D006197:Hair / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D011778:Q Fever / Q000188:drug therapy; D013997:Time Factors; D008061:Whipple Disease / Q000188:drug therapy
chemical_list: D000900:Anti-Bacterial Agents; D004318:Doxycycline
keywords: Compliance; Doxycycline; Hair samples; Q fever; Ultra-high performance liquid chromatography; Whipple's disease