Efficacy of Subantimicrobial Dose Doxycycline for Moderate to Severe and Active Graves' Orbitopathy

Efficacy of Subantimicrobial Dose Doxycycline for Moderate to Severe and Active Graves' Orbitopathy: a Prospective, Uncontrolled Pilot Study

The aim of this study is to evaluate the effects of subantimicrobial dose doxycycline (50 mg/d), administered for 12 wk, for patients with active moderate-severe Graves' Orbitopathy (GO).

Graves'orbitopathy is an autoimmune disease characterised by an inflammatory phase followed by fibrosis. Surgery to correct eyelid swelling, proptosis, and diplopia is effective, but can not be done until the inflammatory phase has passed. To arrest the inflammatory phase, several types of immunosuppressive treatments have been investigated. Corticosteroids are the first-choice immunosuppressive treatment, but they often cause severe side-effects.

Subantimicrobial dose doxycycline posses known anti-inflammatory effects that are separate from their antibacterial mode of action. This mode of action has lead to the routine use of subantimicrobial dose doxycycline for rosacea, periodontitis and multiple sclerosis.

We propose to test the effect of subantimicrobial dose doxycycline for non-sight threatening, moderate-severe, inflammatory GO.

Inclusion Criteria:

• Clinical diagnosis of Graves' Orbitopathy
• Moderate-severe GO According to EUGOGO statements, patients with moderate-severe GO usually have any one or more of the following：moderate or severe soft tissue involvement, exophthalmos≥3mm above normal for race and gender, inconstant, or constant diplopia.
• Clinical activity score ≥ 3
• Being euthyroid for at least 1 month before the date of inclusion
• Must be able to swallow tablets
• Written informed consent is obtained

Exclusion Criteria:

• Mild Graves' Orbitopathy
• Sight-threatening Graves' Orbitopathy
• Clinical activity score < 3
• Previous treatment for GO Oral steroids, intravenous steroids, radiotherapy
• Pregnant females as determined by positive (serum or urine) Human chorionic gonadotropin (hCG) test at screening or prior to dosing, or lactating females
• Uncontrolled diabetes or hypertension
• History of mental / psychiatric disorder
• Hepatic dysfunction (Albumin (Alb),Aspartate Transaminase (AST), Alanine Aminotransferase (ALT) and Alkaline phosphates levels must be within normal range for eligibility)
• Renal impairment (Urea and Creatinine levels must be within normal range)
• Doxycycline allergy or intolerance