You are seeing a 35-year-old female in a GP setting who you diagnosed with anterior blepharitis several weeks ago. You do not feel as though a referral was indicated so you advised the patient that symptoms can be controlled via self-care measures such as eyelid hygiene and warm compresses. However, she has returned to inform you that these techniques are not effective and wishes to start medication to help her symptoms. As per the NICE guidelines, what is the most appropriate first line medication to prescribe here?