Comprehensive Notes on Depression and Mania Pharmacology

Classification and Definition of Affective Disorders

• Collective Affective Disorders: Depression and mania are psychiatric illnesses referred to collectively as affective disorders.

• Bipolar Depressive Illness: Another term used for these conditions, highlighting the cyclic nature between emotional extremes.

• Primary Symptom: The fundamental changes associated with this illness are shifts in MOOD.

Definitions: Depression vs. Mania

• Depression: An affective disorder defined by a loss of interest or pleasure in almost all of a person’s usual pastimes or activities.

• Mania: A state of direct contrast to depression, characterized by an elevation of mood.

  • Elation and Euphoria: Heightened energy levels and excessive elation.

  • Behavioral Changes: Chronic irritability, severe insomnia, and hyperactivity.

  • Cognitive and Social Impact: Control of speech activity, impaired judgment, and potential for social embarrassment.

Epidemiology and Global Impact

• Demographics: Depression occurs across all ages, genders, and backgrounds.

• Prevalence: It affects approximately $121 \times 10^6$ people worldwide.

• Disease Burden:

  • In the year 2000, depression was the 4th leading contributor to the global burden of disease.

  • By the year 2020, it was projected to reach 2nd place in rankings across all ages and sexes.

• Clinical Challenges: The disorder is frequently misdiagnosed or under-diagnosed, though it can be reliably diagnosed and treated in primary care settings.

Etiology and Causal Factors

1. Genetic or Hereditary: Predisposition through family history.

2. Biological/Biochemical/Medication: Neurochemical imbalances or drug-induced states.

3. Dietary: Nutritional influences on brain chemistry.

4. Environmental: External stressors and living conditions.

5. Socio-Cultural Factors: Relationships, personality traits, and specific life situations.

Clinical Forms of Depressive Disorders

• Major Depression:

  • One of the most prevalent psychiatric disorders.

  • Manifests as a combination of symptoms interfering with study, work, sleep, eating, and enjoying once-pleasurable activities.

  • Episodes may occur once or recur throughout a lifetime.

• Dysthymia (Minor Depression):

  • A less severe but chronic form of depression that lasts a long time.

  • Individuals may maintain a normal life but function poorly or feel generally unwell.

  • Major depressive episodes can still occur during dysthymia.

• Bipolar Disorder:

  • Characterized by cycling mood swings between severe highs (mania) and lows (depression).

  • Swings can be rapid and dramatic or gradual.

  • Manic Stage: Involves being overactive, over-talkative, and having extreme energy levels, which affects judgment and social behavior.

• Reactive Depression:

  • A temporary state related to specific life events (e.g., losing a job or a partner).

  • Symptoms may be severe but typically subside within two weeks to six months.

• Atypical Depression:

  • Characterized by non-constant symptoms; the patient may fluctuate between deep depression, anxious irritability, and feeling fine.

• Seasonal Affective Disorder (SAD):

  • Also known as "winter blues," caused by a lack of sunlight.

  • Onset usually occurs in late autumn and clears in early spring as daylight hours increase.

• Postpartum Depression:

  • Resulting from hormonal changes following childbirth combined with the challenges of infant care.

  • Affects approximately $\frac{2}{3}$ of new mothers.

Signs and Symptoms of Depression

• Emotional/Cognitive: Sadness, hopelessness, lack of enthusiasm, motivation, or energy.

• Behavioral: Withdrawal from activities and friends, poor school performance, restlessness, and agitation.

• Interpersonal: Anger, rage, overreaction to criticism, and problems with authority.

• Physical/Biological: Changes in sleeping or eating patterns.

• Psychological: Poor self-esteem, guilt, indecision, difficulty concentrating, and forgetfulness.

• Risk Factors: Substance abuse and suicidal thoughts or actions (occurring in $10\text{--}15\%$ of cases).

Pathophysiology: The Biogenic Amine Hypothesis

• Depression: Caused by a functional DEFICIENCY of monoaminergic transmitters in the brain, specifically:

  • Norepinephrine ($NE$)

  • Serotonin ($5-HT$)

  • Dopamine ($DA$)

• Mania: Caused by a functional EXCESS of monoamines at critical synapses in the brain.

• Monoaminergic Systems: Consist of noradrenergic, serotonergic, and dopaminergic neurons. They regulate mood, vigilance, motivation, fatigue, and psychomotor activity.

• Mechanisms of Dysfunction: Abnormal states arise from altered synthesis, storage, or release of neurotransmitters, as well as disturbed receptor sensitivity or subcellular messenger functions.

Clinical Management and Treatment Goals

• Management Approaches: Non-pharmacological, pharmacological, and Electroconvulsive Therapy (ECT).

• Primary Goals:

  • Reduce symptoms of acute depression.

  • Facilitate return to pre-illness level of functioning.

  • Prevent future depressive episodes.

• Diagnosis Tools: History collection and Mental Status Examination.

Psychotherapy and Specialized Treatments

• Cognitive-Behavioral Therapy (CBT): Assists patients in restructuring negative thought patterns.

• Interpersonal Therapy (IPT): Focuses on working through troubled relationships that contribute to depression.

• Electroconvulsive Therapy (ECT): Used for treatment-resistant depression when medication or psychotherapy fails.

Pharmacology of Antidepressants

• Mechanism of Action: Antidepressants slow the removal of $NE$ and $5-HT$ from the brain, increasing their availability at the synapse. This stabilizes and normalizes neurotransmitters to regulate mood.

Classification of Antidepressants

1. Tricyclic Antidepressants (TCAs):

   • Tertiary Amines: Amitriptyline, Clomipramine, Doxepin, Imipramine, Trimipramine.

   • Secondary Amines: Amoxapine, Desipramine, Maprotiline, Nortriptyline, Protriptyline.

2. Selective Serotonin Reuptake Inhibitors (SSRIs): Fluoxetine, Fluvoxamine, Paroxetine, Venlafaxine (often classed as SNRI), Sertraline, Citalopram, Escitalopram.

3. Monoamine Oxidase Inhibitors (MAOIs): Phenelzine, Tranylcypromine, Selegiline, Isocarboxazid, Moclobemide.

4. Atypical Antidepressants: Bupropion, Nefazodone, Trazodone, Mirtazapine.

5. Serotonin/Norepinephrine Reuptake Inhibitors (SNRIs): Venlafaxine, Duloxetine.

Tricyclic Antidepressants (TCAs) in Detail

• Prototypes: Imipramine and Amitriptyline.

• Mechanism: Mixed inhibitors of $NE$ and $5-HT$ uptake. They block presynaptic uptake transporters, leading to neurotransmitter buildup at the synapse.

• Pharmacological Profile:

  • Blockade of presynaptic $NE$ and $5-HT$ transporters.

  • Blockade of postsynaptic Histamine ($H_1$) receptors.

  • Blockade of postsynaptic Acetylcholine ($ACh$) receptors.

• Effects on CNS:

  • In normal subjects, they cause unpleasant side effects (sleepiness, fall in BP, thinking difficulties).

  • In depressed patients, they cause mood elevation, typically manifesting after $2\text{--}3$ weeks.

• Effects on Sleep: Used as sedative-hypnotics.

  • Decrease number of awakenings.

  • Increase Stage 4 (deep) sleep.

  • Decrease total REM (Rapid Eye Movement) sleep.

• Effects on ANS: Inhibition of $NE$ transport, blockade of muscarinic and $\alpha_1$ adrenergic receptors.

• Effects on CVS: Therapeutic doses cause sinus tachycardia and postural hypotension. Overdosage leads to ECG flattening of T waves and prolongation of conduction time.

• Pharmacokinetics:

  • Lipophilic and highly protein-bound.

  • Metabolized in the liver (oxidation followed by glucuronic acid conjugation).

  • Intermediates can be active (e.g., Imipramine to Desipramine).

  • Readily cross the placenta.

• Adverse Effects: Anti-muscarinic effects (dry mouth, blurred vision, urinary retention in prostatic hypertrophy), cerebral intoxication, weight gain (increased appetite), and impotence. Contraindicated in pregnancy and lactation.

• Interactions: Highly competitive for protein binding with drugs like Phenytoin.

Selective Serotonin Reuptake Inhibitors (SSRIs)

• Overview: Increase available serotonin to stimulate postsynaptic receptors. Used for depression, anxiety, obesity, and alcohol abuse.

• Fluoxetine (Prozac): First SSRI; half-life of $4$ days; slow onset; side effects include anxiety, insomnia, agitation, and sexual dysfunction.

• Sertraline (Zoloft): Low toxicity risk; more selective and potent than Fluoxetine.

• Paroxetine (Paxil): Highly effective for PTSD, OCD, panic disorder, and social phobia.

• Fluvoxamine (Luvox): Derivative of Fluoxetine; used for OCD and PTSD.

• Citalopram (Celexa): Well-absorbed orally; used for major depression and social phobia.

Monoamine Oxidase Inhibitors (MAOIs)

• Mechanism: Inhibit enzymes that break down $5-HT$ and $NE$.

  • MAO-A: Inhibition provides antidepressant effects.

  • MAO-B: Inhibition is associated with side effects.

• Irreversible MAOIs: Nonselective (block A and B); form permanent bonds. Examples: Phenelzine, Tranylcypromine, Isocarboxazid.

• Reversible MAOIs (RIMAs): Selective for MAO-A; safer with minimal side effects. Example: Moclobemide.

• Dietary Warning: Interaction with tyramine-rich foods (red wine, pickled foods, yeast extract, aged cheeses, broad beans) can cause a hypertensive crisis, sweating, and vomiting.

Management of Mania: Lithium

• Clinical Use: Prophylaxis and control of mania, hypomania, and bipolar depression.

• Mechanism of Action: Similar to sodium ($Na^+$); passes through $Na^+$ channels and accumulates inside neurons. It may interfere with action potentials or second messengers involved in $NE$ release.

• Pharmacokinetics: Narrow therapeutic ratio; requires strict blood concentration monitoring.

• Toxicity: Early signs include vomiting, severe diarrhea, tremors, ataxia, renal impairment, and convulsions.

• Interactions:

  • NSAIDs: Increase lithium plasma concentration and toxicity risk (Aspirin is the exception and is safe).

  • ACE Inhibitors: Can lead to increased lithium levels.

• Patient Education: Patients must use the same brand of Lithium due to bioavailability differences between brands.

Clinical Indications for Antidepressants

• Depression: Primary use.

• Anxiety Disorders: Panic, GAD, and social phobia (SSRIs, Venlafaxine, Duloxetine).

• OCD: Fluoxetine and other SSRIs.

• Enuresis: TCAs.

• Chronic Pain: Venlafaxine and Duloxetine.

• Bulimia: Fluoxetine.

Therapeutic Dosage and Plasma Guidelines

Medical and Drug-Induced Depressive Symptoms

• General Medical Conditions: Hypothyroidism, Addison or Cushing disease, Pernicious anemia, AIDS, Hypokalemia, Hyponatremia, Coronary artery disease, Alzheimer’s, Epilepsy, Parkinson’s, and Multiple Sclerosis.

• Substance Use: Alcoholism, marijuana, nicotine, and opiate abuse.

• Drug Therapy Side Effects:

  • Antihypertensives: Clonidine, Guanethidine, Methyldopa, Propranolol, Reserpine.

  • Hormonal: Oral contraceptives, Steroids.

  • Others: Isotretinoin, Interferon-$\beta_{1a}$.

Patient Medication Safety Guidelines

Do's

• Follow doctor’s directions and read prescription labels carefully.

• Pay attention to dosage, usage, precautions, and side effects.

• Store medication properly and take it at the same time each day.

• Complete the full course of treatment.

Don'ts

• Do not change dosage or stop medication without medical advice.

• Do not consume alcohol with medication.

• Do not transfer medication to other bottles or mix different medications in one bottle.

• Do not take other medications unless directed by a doctor.