MITAPREX 30 MG is a tablet containing 30 milligrams of mirtazapine. 1 Mirtazapine is an antidepressant medication belonging to the tetracyclic antidepressant class. 2 It is prescribed for the treatment of major depressive disorder. 3 Mirtazapine works by influencing the levels of certain neurotransmitters in the brain, primarily norepinephrine and serotonin, which can help to improve mood, reduce anxiety, and aid in better sleep and appetite. 4