Pharmacology of Mental Health and Psychotropic Medications

Advanced Medication Selection and Pharmacogenomics

• Pharmacogenomics and Testing: Current healthcare utilizes genetic swabbing to determine medication compatibility based on a patient's unique genetic makeup. This represents a significant advancement over the historical "trial and error" process.

• The Historical Trial and Error Process: Previously, patients were started on a medication and required to wait approximately $6\,\text{weeks}$ to determine effectiveness. If ineffective, dosages were titrated or the medication was tapered off entirely, followed by a "break" period before starting a new drug. This cycle could repeat multiple times, delaying effective treatment.

• Modern Approach: A simple genetic swab can now identify which medications are likely to be effective for a specific individual, streamlining the path to therapeutic stability.

Holistic Management and Treatment Barriers

• Multimodal Therapy: Medication should ideally be paired with non-pharmacologic therapies, such as Cognitive Behavioral Therapy (CBT), to develop coping strategies and management skills for mental illness.

• Non-Pharmacologic Interventions:

  • Support groups.

  • Exercise: Exercise releases endorphins, which serve as a natural component of the mental health "toolbox."

• Barriers to Compliance:

  • Side Effects: Using Selective Serotonin Reuptake Inhibitors (SSRIs) as an example, side effects like decreased sexual libido (impotence in males) can be so detrimental that patients discontinue therapy.

  • Symptom Interference: In disorders like schizophrenia, full symptom control is often elusive. Hallucinations may command a patient to stop taking their medication, claiming the medication is an attempt to kill them.

  • Assessment: Nursing staff must assess for these barriers to improve adherence.

Classifications of Mental Health Disorders

• Neurotransmitter Basis: Mental health disorders are primarily understood through the lens of neurotransmitters. Most medications aim to balance these chemicals, specifically Dopamine, Serotonin, Epinephrine, and Norepinephrine.

• Broad Therapeutic Categories:

  • Anxiety: Characterized by hyperfixation, fear, and cycles of irrational thought. It is distinguished from normal anxiety by its impact on everyday life.

  • Affective (Mood) Disorders: This category includes Major Depressive Disorder and Bipolar Disorder.

  • Psychosis: Defined as losing touch with reality. Patients may "add" to reality (positive symptoms like hallucinations) or "subtract" from it (negative symptoms like apathy).

Detailed Analysis of Anxiety Disorders

• Normal vs. Pathological Anxiety: Normal anxiety is a healthy motivator (e.g., motivating a student to study). Anxiety disorder goes beyond the rational level and becomes obsessive or irrational.

• The Anxiety Cycle: Anxiety involves a rapid transition from rational concerns to irrational escalations (e.g., catastrophizing a skin spot into terminal melanoma involving metastasis to the brain).

• Physical Ramifications: Chronic "fight or flight" activation can lead to physiological changes, including increased heart rate and elevated blood pressure.

• Six Main Classifications:

  1. Generalized Anxiety Disorder (GAD): General anxiety not necessarily tied to a single specific trigger; it applies to various situations.

  2. Panic Disorder: Characterized by sudden panic attacks which may occur without prior anxiety. Physical symptoms can mimic cardiac events (numbness in arms, chest discomfort), often requiring EKGs or stress tests to rule out myocardial infarction.

  3. Obsessive-Compulsive Disorder (OCD): Driven by compulsions that must be completed to alleviate anxiety. Examples include flipping light switches a specific number of times or an obsession with germ avoidance (misophobia).

  4. Social Anxiety Disorder: Intense fear or anxiety triggered by social settings or being around other people (e.g., inability to go grocery shopping at a crowded store).

  5. Phobias: Intense, irrational fears of specific objects or situations (e.g., heights, spiders).

  6. Post-Traumatic Stress Disorder (PTSD): Resulting from a traumatic, stressful event. While common in veterans, it also affects healthcare workers (e.g., ER nurses) who have experienced workplace violence or attacks, leading to symptoms such as nightmares.

Bipolar and Psychotic Disorders

• Bipolar Disorder: Characterized by shifts between two polar extremes: mania and depression.

  • Mania: Levels of mania vary. While some associate it with extreme behaviors like street racing at $160\,\text{mph}$, it can also manifest as bursts of high energy, such as compulsively rearranging furniture or running a full marathon ($26.2\,\text{miles}$) unexpectedly on a weekday night.

• Psychosis and Schizophrenia: Involves a separation from reality.

  • Drug-Induced Psychosis: Certain medications or substances can induce hallucinations.

  • Depressive Psychosis: Severe depression can lead to psychotic states.

Pharmacotherapy for Anxiety: Benzodiazepines

• Mechanism and Suffixes: Often ending in "-pam" or "-lam" (e.g., Lorazepam, Alprazolam).

• Antidote: Flumazenil is the specific antidote for benzodiazepine overdose.

• Side Effects: CNS depression, drowsiness, and dizziness.

• Alternative Uses: Alcohol withdrawal and seizure management.

• Special Population (Elderly): High risk for paradoxical reactions, where the medication causes increased agitation instead of sedation.

• Safety and Discontinuation:

  • Black Box Warning: Use with opioids significantly increases the risk of fatal CNS depression and respiratory failure.

  • Rebound/Withdrawal: These must not be stopped abruptly. Sudden discontinuation can lead to withdrawal seizures, even if the patient does not have a history of epilepsy.

  • Lethality: Overdose on benzodiazepines alone is rarely fatal; death usually occurs when combined with other CNS depressants like alcohol or opioids.

Miscellaneous Anxiety and Mood Stabilizers

• Buspirone: A miscellaneous anti-anxiety med with an unknown mechanism of action. While often ordered PRN (as needed), it is not ideal for PRN use. It carries a risk of Serotonin Syndrome when combined with other serotonergic drugs.

• Lithium (Mood Stabilizer):

  • Therapeutic Index: Extremely narrow therapeutic range ($0.6\,\text{mEq/L}$ to $1.2\,\text{mEq/L}$; though values vary, the gap is very thin). Toxicity is life-threatening, often resulting in the "seizure, coma, death" progression.

  • Monitoring: Requires monitoring of kidney function ($\text{BUN}$, $\text{Creatinine}$, $\text{GFR}$) because the drug is excreted renally.

  • Sodium and Hydration: Lithium levels are inversely related to sodium. Low sodium levels or dehydration can increase lithium levels to toxic concentrations. Patients must maintain a consistent sodium intake and avoid drastic changes in hydration.

  • Adverse Effects: Cardiac dysrhythmias and hypothyroidism. Monitoring $\text{TSH}$, $\text{T3}$, and $\text{T4}$ is required.

  • Interactions: Diuretics (fluid/electrolyte balance), ACE inhibitors (kidney/electrolyte effects), and NSAIDs (kidney function).

Antidepressant General Principles

• Safety and Suicide Risk: The biggest risk when starting antidepressants is suicide.

• Black Box Warning: Applies to pediatrics and young adults. As the medication starts to work (after approximately $2\,\text{weeks}$), the patient may gain the energy and motivation to carry out a suicide plan before their mood has fully lifted.

• Timing of Effectiveness: Minimum of $2\,\text{weeks}$ for initial effect, with maximum effectiveness reached at $6$ to $8\,\text{weeks}$.

Classes of Antidepressants

• Tricyclic Antidepressants (TCAs):

  • Examples: Amitriptyline and Nortriptyline.

  • Current Primary Use: Neuropathic pain (e.g., diabetic neuropathy) and insomnia due to their sedative effects.

  • Toxicity: Highly lethal in overdose; $70\%$ to $80\%$ of patients who overdose on TCAs die before reaching the hospital due to cardiac stimulation/dysrhythmias.

  • Adverse Effects: Anticholinergic effects (the "four cants") and impotence.

• Monoamine Oxidase Inhibitors (MAOIs): Historically used for severe depression and Parkinson's. They require a long "washout period" before starting other medications due to high interaction risks.

• SSRIs and SNRIs: The "second generation" or newer classes with fewer side effects.

  • Common Meds: Fluoxetine (Prozac), Citalopram, Escitalopram, Duloxetine (Cymbalta - also used for pain).

  • Adverse Effects: Excessive sweating, GI upset (common in the first month), weight gain, and QT prolongation.

  • QT Prolongation: Can lead to a specific, fatal dysrhythmia called Torsades de Pointes (characterized by a "twisting" appearance on ECG, similar to a DNA helix).

  • Discontinuation: Must be tapered. Abrupt cessation leads to physical withdrawal and emotional outbursts (e.g., anger).

Serotonin Syndrome

• Pathophysiology: Excess serotonin levels leading to over-excitation of the body.

• Symptoms (SHIVERS Mnemonic):

  • S: Shivering (muscle tremors/shaking).

  • H: Hyperreflexia.

  • I: Instability (Autonomic instability: high HR, high BP, high Temp).

  • V: Vital sign changes.

  • E: Encephalopathy (Altered mental status, delirium).

  • R: Restlessness.

  • S: Sweating.

• Complications: Hyperthermia (due to excessive muscle activity and metabolism) and excited bowels (diarrhea).

• Interactions: St. John's Wort (known as "nature's Prozac") significantly increases the risk of Serotonin Syndrome.

Antipsychotic Medications

• Generations:

  • First Generation: Older, more side effects.

  • Second Generation: Better tolerated but higher risk of weight gain and metabolic issues (Insulin resistance/Diabetes, increased lipids).

• Notable Medications: Risperidone, Quetiapine (Seroquel), Olanzapine, Haloperidol (Haldol), and Clozapine.

• Clozapine: Requires being on a national registry due to the risk of severe blood dyscrasias (requires frequent CBC monitoring for white blood cell counts).

• Adverse Effects and Movement Disorders:

  • Extrapyramidal Symptoms (EPS): Abnormal full-body muscle movements.

  • Akathisia: A form of EPS characterized by motor restlessness (e.g., constant pacing).

  • Tardive Dyskinesia (TD): Characterized by involuntary facial movements; often irreversible if not caught early.

  • Pseudo-Parkinsonism: Antipsychotics block dopamine, which can make a patient appear to have Parkinson's disease.

  • Neuroleptic Malignant Syndrome (NMS): A rare, life-threatening emergency similar to Serotonin Syndrome; requires immediate medication cessation.

• Long-term Risks: Because they affect dopamine, long-term use can increase the risk of depression and suicidal ideation.