title: Effectiveness of low-dose doxycycline (LDD) on clinical symptoms of Sjögren's syndrome: a randomized, double-blind, placebo controlled cross-over study.
abstract: BACKGROUND
  Matrix metalloproteinases (MMPs) are proteolytic enzymes that may contribute to tissue destruction in Sjögren's syndrome (SS). Low-dose doxycycline (LDD) inhibits MMPs. We evaluated the efficacy of LDD for the subjective symptoms in primary SS patients. This was a randomized, double blind, placebo controlled cross-over study. 22 patients were randomly assigned to receive either 20 mg LDD or matching placebo twice a day for 10 weeks. The first medication period was followed by 10-week washout period, after which the patient received either LDD or placebo, depending on the first drug received, followed by the second washout period. Stimulated saliva flow rates and pH were measured before and after one and ten weeks of each medication and after washout periods. VAS scale was used to assess the effect of LDD and placebo on following six subjective symptoms: xerostomia; xerophtalmia; difficulty of swallowing; myalgia; arthralgia; and fatigue. The effect was evaluated for each medication and washout period separately.
  
  
  RESULTS
  Overall, the effects of medications on subjective symptoms were minor. Wilcoxon test demonstrated increased fatigue with LDD during medication (p < 0.05). The differences may, however, reflect normal fluctuation of symptoms in SS patients.
  
  
  CONCLUSIONS
  LDD may not be useful in reducing the primary SS symptoms.
authors.affiliation: Institute of Dentistry, University of Helsinki, and Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital (HUCH), PO BOX 14, 00014 University of Helsinki, Finland. hseitsalo@medone.fi
authors.forename: Hubertus
authors.initials: H
authors.lastname: Seitsalo
authors.forename: Raija K
authors.initials: RK
authors.lastname: Niemelä
authors.forename: Magdalena
authors.initials: M
authors.lastname: Marinescu-Gava
authors.forename: Tuija
authors.initials: T
authors.lastname: Vuotila
authors.forename: Leo
authors.initials: L
authors.lastname: Tjäderhane
authors.forename: Tuula
authors.initials: T
authors.lastname: Salo
mesh_terms: D018592:Cross-Over Studies; D004311:Double-Blind Method; D004318:Doxycycline / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D012472:Salivation / Q000187:drug effects / Q000502:physiology; D012636:Secretory Rate / Q000187:drug effects / Q000502:physiology; D012859:Sjogren's Syndrome / Q000188:drug therapy* / Q000503:physiopathology*
chemical_list: D004318:Doxycycline