WASHINGTON (AP) — Federal regulators are still investigating the safety of Pfizer’s anti-smoking drug Chantix, a probe that began last year after thousands of patients reported blackouts and other problems. Chantix is among the 20 medications under investigation for potential safety issues on an updated list from the FDA. The FDA is investigating reports of injury, visual impairment and other problems connected with the medication, which is designed to ease smokers’ withdrawal symptoms. The agency began probing the problems last fall. Elsewhere, the Federal Aviation Administration last year banned the use of Chantix by pilots after a spike in patients reporting blackouts, some of which led to traffic accidents.