A doctor whose medical practice is charged in a whistleblower lawsuit with violating rules regarding controlled substances denied the allegations Tuesday, saying his former employee's motivation is to pressure him into paying her off. Dr. Mustafain Meghani of Troy-based Upstate Physician Services said that the former employee, Jessica Merola of Wynantskill, is wrong in asserting the medical practice improperly prescribed Suboxone, a medication to treat patients addicted to opioids, and inadequately responded to another employee's efforts to obtain prescription medications for herself.