Hello. Minonil ER (Minocycline) dosage is strictly determined by your body weight (typically 1 mg/kg daily). Generally, the 45 mg strength is prescribed for individuals weighing 45-59 kg (99-131 lbs), while the 65 mg strength is for those weighing 60-89 kg (132-196 lbs). Because taking the wrong dose can cause unnecessary side effects or lessen the treatment?s effectiveness, you should not guess. Please contact your prescribing dermatologist or the dispensing pharmacy to verify your exact prescription on file. You can safely continue using the Tretinoin ointment at night as directed in the meantime.