Clinical Research Directory

Inclusion Criteria: * Outpatients * NINCDS/ADRDA criteria for probable AD * MMSE at assessment = 10-30 * Identified informant to accompany patient at all visits * Stable dose of donepezil, galantamine or rivastigmine for preceding 12 weeks Exclusion Criteria: * Labile blood pressure or new antihypertensive medication started within 3 weeks * Severe coronary insufficiency or myocardial infarction in previous 6 months * History of unexplained syncope within the preceding 12 months * Cardiac Conduction Block * Severe Hepatic Impairment (ALT \> 120 (Upper Limit of Normal (ULN) is 40) OR Alkaline Phosphatase \> 390 (ULN 130)) OR Both ALT and total bilirubin \> ULN OR Total bilirubin \> 60 (ULN 30) * Severe Renal Impairment (eGFR \< 40) * Treatment with other medications known to potentiate guanfacine's hypotensive effects or cause arrhythmia (specifically antipsychotics (including sultopride, chlorpromazine, thioridazine, amisulpiride, sulpiride, haloperidol), and moxifloxacin, baclofen, verapamil, quinidine, hydroquinidine, dispyramide, amiodarone, dofetilide, ibutilide, sotalol, pimazide, bepridil, cisapride, diphemanil, erythromycin, halofantrine, pentamidine, sparfloxacin, vincamine, alfuzosin, prazosin, terazosin, tamsulosin, amifostine * Weight less than 45kg * Pregnancy (Pre-menopausal women will only be entered into the study of they are surgically sterile or using effective birth control methods: These are abstinence for the period of the study, intrauterine contraception/device, male sexual partners with vasectomy)