Cloxacillin Powder is the best option to avail the benefits of cloxacillin if the patient is unable to consume a tablet. Great for treating various bacterial infections, this medication belongs to the family of penicillin antibiotics. Cloxacillin Power works by preventing the development of bacteria within the patientâs body. However, many people get confused with bacterial and viral infections. It is taken by mouth on an empty stomach or can a couple of hours after meal, otherwise directed by the doctor.