Mirtazapine, USP is a white to creamy white crystalline powder which is slightly soluble in water. Mirtazapine Tablets, USP are supplied for oral administration as scored tablets containing 15 mg or 30 mg of mirtazapine, USP, and unscored tablets containing 7.5 mg or 45 mg of mirtazapine, USP. Mirtazapine is a white to creamy white crystalline powder which is slightly soluble in water. REMERON is supplied for oral administration as scored film-coated tablets containing 15 or 30 mg of mirtazapine, and unscored film-coated tablets containing 45 mg of mirtazapine. The usual dose is one tablet each day, taken at bedtime. It may take up to four weeks after starting this treatment before you feel the full benefit. Do not stop taking it, feeling it is not helping. It is common to feel sleepy when you first start taking mirtazapine. Depression can develop for no Detailed drug Information for mirtazapine. Includes common brand names, drug descriptions, warnings, side effects and dosing information. Mirtazapine is an appetite stimulant for pets suffering from stomach problems or cancer treatments. Mirtazapine is a prescription medication and is sold per tablet. Buy it today at America's Largest Pet Pharmacy. Abrupt discontinuation of mirtazapine should be avoided when possible. Adverse effects have been reported upon discontinuation of the drug including nausea, vomiting, agitation, sensory disturbances, sweating, and headache. Describes the medication mirtazapine (Remeron, Soltab), a drug used for the treatment of depression and posttraumatic stress disorder (PTSD). Side effects and drug interactions are included in the information. Read more about the prescription drug mirtazapine (Remeron, Soltab). Abrupt discontinuation of mirtazapine should be avoided when possible. Adverse effects have been reported upon discontinuation of the drug including nausea, vomiting, agitation, sensory disturbances, sweating, and headache. Posology. Adults. The effective daily dose is usually between 15 and 45 mg; the starting dose is 15 or 30 mg. Mirtazapine begins to exert its effect in general after 1-2 weeks of treatment. Mirtazapine is used to treat depression. Mirtazapine is in a class of medications called antidepressants. It works by increasing certain types of activity in the brain to maintain mental balance.