Increased plasma levels w/ drugs known to inhibit CYP1A2 activity. Decreased plasma levels w/ drugs known to induce CYP1A2 activity. Increased AUC w/ fluvoxamine or ciprofloxacin. Co-administration w/ other CYP1A2 inhibitors eg, antiarrhythmics (amiodarone, mexiletine, propafenone), cimetidine, fluoroquinolones (enoxacin, pefloxacin, norfloxacin), rofecoxib, OCs, & ticlopidine. Drugs known to prolong QT interval (including but not limited to cisapride, amytriptyline & azithromycin). Concomitant use w/ antihypertensives, including diuretics. Decreased conc w/ rifampicin. Decreased systemic exposure w/ cigarettes. Enhanced CNS depressant effects of alcohol. Enhanced sedative action w/ sedatives, hypnotics (eg, benzodiazepine or baclofen), & other drug eg, antihistamines. Potential additive hypotensive effect w/ other α-2 adrenergic agonists (eg, clonidine).