Schizophrenia: A 23-year-old male presents with auditory hallucinations, paranoia, social withdrawal, and flattened affect that have progressively worsened over eight months. This case emphasizes distinguishing positive and negative symptoms, performing differential diagnosis, and selecting antipsychotic treatment. Lithium Toxicity: A patient with Bipolar I disorder develops nausea, vomiting, coarse tremors, ataxia, and confusion while receiving lithium therapy. Learners review therapeutic drug monitoring, risk factors for toxicity, laboratory evaluation, and emergency management. Post-Traumatic Stress Disorder (PTSD)A 40-year-old woman develops nightmares, flashbacks, hypervigilance, and avoidance behaviors following a traumatic motor vehicle accident. Students explore trauma-related disorders, evidence-based pharmacotherapy, and trauma-focused psychotherapy interventions. Major Depressive Disorder (MDD)A 34-year-old woman presents with persistent sadness, loss of interest in activities, fatigue, insomnia, poor concentration, and feelings of worthlessness for two months. Learners practice recognizing depressive symptoms, assessing suicide risk, selecting appropriate screening tools, and initiating evidence-based treatment with SSRIs and psychotherapy. Attention-Deficit/Hyperactivity Disorder (ADHD)An 11-year-old boy experiences inattention, distractibility, poor academic performance, and impulsive behavior both at school and home. Students learn diagnostic criteria, differential diagnoses, and first-line pharmacologic and behavioral treatment approaches. Opioid Use Disorder: A 36-year-old man struggles with cravings, tolerance, withdrawal symptoms, and repeated unsuccessful attempts to stop opioid use. This case highlights medication-assisted treatment, overdose management, and long-term recovery strategies while emphasizing the role of buprenorphine and naloxone.

Psychopharmacology aims to restore dysregulated neurotransmitter systems that underline psychiatric symptoms. Effective prescribing requires understanding the relationship between symptom clusters, neurobiology, medication mechanisms, and safety monitoring. PMHNPs must balance efficacy with adverse effects, medical comorbidities, drug interactions, age-related considerations, and patient preferences. Neurotransmitter Systems and Medication Targets Serotonin Dysregulation Serotonin pathways originating from the raphe nuclei regulate mood, anxiety, obsessive thoughts, sleep, appetite, and emotional processing. Reduced serotonergic transmission contributes to depression, generalized anxiety disorder, panic disorder, PTSD, and OCD. Clinical Manifestations Depressed mood, Anhedonia, Excessive worry, Rumination, Panic symptoms, Obsessions and Compulsions. Medication Classes SSRIs Examples: Sertraline, Escitalopram, Fluoxetine, Paroxetine, & Citalopram Mechanism: Block serotonin reuptake transporter (SERT), increasing serotonin availability. First-line indications: Major depressive disorder, Generalized anxiety disorder, Panic disorder, PTSD, & OCD Common adverse effects: Nausea, Sexual dysfunction, Insomnia, Headache Serious risks: Serotonin syndrome, SIADH/hyponatremia, Increased bleeding risk & QT prolongation (especially citalopram) SNRIs. Examples: Venlafaxine, Duloxetine, Desvenlafaxine Mechanism: Increase serotonin and norepinephrine transmission. Useful when depression coexists with: Neuropathic pain, Fibromyalgia, &Chronic pain syndromes. Potential adverse effects: Hypertension, Sweating, Anxiety &Withdrawal symptoms