MH mod 2B

Antidepressants and mood stabilizers are crucial pharmacological treatments for a range of mental health conditions, primarily affecting mood and emotional regulation. While antidepressants are typically prescribed for depressive disorders, they also find use in anxiety and other conditions. Mood stabilizers, on the other hand, are the cornerstone of treatment for bipolar disorder.
Generally, these medications work by modulating neurotransmitter activity in the brain, though their specific mechanisms vary significantly across different classes of drugs. Understanding their classifications, mechanisms, indications, and side effects is essential for effective clinical practice.

Classification of Antidepressants:
  • SSRIs (Selective Serotonin Reuptake Inhibitors): These are among the most commonly prescribed antidepressants, known for selectively inhibiting serotonin reuptake.
  • Atypical Antidepressants: This diverse group includes drugs with unique mechanisms that differ from SSRIs, TCAs, and MAOIs.
  • Tricyclic Antidepressants (TCAs): Older antidepressants with a broader neurotransmitter profile but also a less favorable side effect profile.
  • MAOIs (Monoamine Oxidase Inhibitors): Another older class, highly effective but with significant dietary and drug interaction restrictions.
Classification of Mood Stabilizers:
  • Older Mood Stabilizers: Includes established treatments like lithium and certain anticonvulsants.
  • Newer Mood Stabilizers: Comprises more recently developed compounds, often with different efficacy and side effect profiles.

SSRIs (Selective Serotonin Reuptake Inhibitors)

General Overview
  • SSRIs are a class of antidepressants known for their effectiveness in the treatment of depression and anxiety disorders.
  • Main SSRIs:
    • Fluoxetine (Prozac)
    • Citalopram (Celexa)
    • Escitalopram (Lexapro)
    • Paroxetine (Paxil, Pexeva)
    • Sertraline (Zoloft)
    • Fluvoxamine (Luvox) (specifically used to treat OCD)
  • Annual Sales: SSRIs generate approximately 12billion12 billion.
  • Patient Starts: Between 1988 and 2002, approximately 67.5 million patients started treatment with Prozac, Paxil, or Zoloft.
Mechanism of Action
  • Primary Action: SSRIs inhibit the reuptake of serotonin, resulting in increased levels of serotonin in the synaptic cleft.
  • Receptor Interactions: At high doses, many SSRIs may affect other receptor types, leading to various clinical effects.
  • Onset of Action: Clinical effects typically take a few weeks to manifest; the mechanism extends beyond mere serotonin level elevation.
  • Serotonin Receptor Subtypes: There are several types of serotonin (5-HT) receptors located throughout the body, particularly concentrated in the gastrointestinal tract.
Indications and Off-label Uses
  • FDA-approved for major depressive disorder and dysthymia (except Luvox).
  • Other indications include:
    • Generalized anxiety disorder
    • Obsessive-compulsive disorder (OCD)
    • Panic disorder
    • Post-traumatic stress disorder (PTSD)
    • Eating disorders
    • Premenstrual dysphoric disorder
    • Social anxiety disorder
  • Off-label Uses: Treatment of ADHD, insomnia, chronic pain syndromes, seasonal affective disorder, and behavioral issues in dementia and mental retardation.
Pharmacokinetics
  • Half-life - SSRIs vary in half-life:
    • Short Half-life: Paroxetine and fluvoxamine (can lead to withdrawal symptoms when doses are missed).
    • Moderate Half-life: Sertraline, citalopram, and escitalopram.
    • Long Half-life: Fluoxetine (beneficial for patients at risk of missing doses).
Side Effects
  • Common side effects include:
    • Sexual Dysfunction: Decreased sex drive and impaired sexual function, often persistent.
    • Gastrointestinal Effects: Nausea, diarrhea, anorexia, and vomiting may increase with dose.
    • Weight Changes: Possible weight gain, particularly with paroxetine.
    • Neurological Impact: Headache, dizziness, anxiety (common with fluoxetine), and insomnia.
    • Other Effects: Rash, sedation, sweating, vivid dreams, tremor, dry mouth (notably with paroxetine), and bruising.
Drug-drug Interactions (DDI)
  • Impact of SSRIs on Interactions (from least to most significant):
    • Celexa (Citalopram)
    • Lexapro (Escitalopram)
    • Zoloft (Sertraline)
    • Paxil (Paroxetine)
    • Prozac (Fluoxetine)
    • Luvox (Fluvoxamine)
  • Many interactions may depend on dosage, with specific examples including:
    • Paroxetine leading to increased levels of risperidone.
    • Fluoxetine raising buspirone levels.
    • Fluvoxamine increasing olanzapine levels.
Cautions and Risks
  • Suicidal Ideation: Increased risk, especially in children during initial treatment (controversy exists regarding this caution).
  • Serotonin Syndrome: Risk when combined with MAOIs or other serotonergic agents, presenting with symptoms such as:
    • Diarrhea, tremor, sweating, restlessness
    • Progressing to disorientation, rigidity, fever, coma, and in severe cases death (approximately 10% mortality rate).
  • Drugs with Serotonin Activity: Caution with substances like dextromethorphan, fentanyl, meperidine, sumatriptan, St John’s Wort, MDMA (ecstasy), and LSD.
Overview of Specific SSRIs
  • Citalopram (Celexa):