Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial

Inclusion Criteria:

* Patients 55 years of age or older, women post-surgical menopause or at least two years since last menses if natural menopause.
* CT scan documented infrarenal abdominal aortic aneurysm with maximum transverse diameter larger than 35 mm and no greater than 50 mm, in men, and larger than 35 mm and no greater than 45 mm in women.

Exclusion Criteria:

* Patients will be excluded from the study if they are unable to give their own informed consent to participate.
* have symptoms related to abdominal aortic aneurysm.
* have other intra-abdominal vascular pathology that may require repair within 24 months (e.g., renal artery stenosis, large iliac artery aneurysms, iliac occlusive disease, aneurysmal involvement of the renal artery).
* have had previous abdominal aortic aneurysm repair by open surgical or endovascular technique.
* have an active malignancy with life expectancy less than two years.
* have an allergy to tetracycline.
* are currently or have been recently treated (previous six months) with tetracycline derivatives.
* they are currently taking anti-seizure medicines metabolized by pathways influenced by doxycycline (e.g., carbamazepine, phenytoin, and barbiturates).
* stage II hypertension (patients whose blood pressure is persistently in the range of systolic \> 160 mm Hg or diastolic \> 100 mm Hg despite primary physician's best effort to achieve adequate therapy.
* have dialysis dependent renal failure or impending dialysis treatment for renal insufficiency.
* have a chronic infection requiring long-term (\> 2 weeks) antibiotics.
* have known genetic syndromes responsible for the abdominal aortic aneurysm (e.g., Marfan's Syndrome).
* are under treatment with systemic immunosuppressive agents.
* could become pregnant.
* are not good candidates for clinical trial participation.
* are enrolled in another clinical trial.