Week 10 Flashcards
SSRI: Onset of Action
4-6 weeks for symptom relief and up to 12 weeks for full effects.
SSRI: Half-lives & Implications
Fluoxetine has the longest half-life (~50 hours, with active metabolite ~10 days), reducing withdrawal risk; paroxetine and sertraline have shorter half-lives and higher risk for discontinuation syndrome.
SSRI: Discontinuation Syndrome
Symptoms include flu-like symptoms, insomnia, imbalance, sensory disturbances, and hyperarousal; more likely with short half-life SSRIs like paroxetine; tapering recommended.
Hypnotics: Adverse Effects
Include dizziness, anterograde amnesia, complex sleep behaviors (e.g., sleepwalking), next-day sedation (especially with ER formulations), and rebound insomnia.
Hypnotics: Management Considerations
Use short-term; choose agent based on half-life and sleep complaint (falling asleep vs. staying asleep); consider safety, especially in elderly.
Methylphenidate: Onset of Action
Rapid onset with IR formulations; ER and patch forms provide extended symptom control over the day.
Methylphenidate: MOA
Inhibits reuptake of dopamine and norepinephrine; increases synaptic concentrations of both neurotransmitters.
TCAs: Clinical Indications
Used for depression, chronic pain (e.g., neuropathy), migraine prophylaxis, and insomnia at low doses.
TCA: Adverse Effects
Anticholinergic (dry mouth, constipation), sedation, weight gain, orthostatic hypotension, cardiotoxicity (QT prolongation), and sexual dysfunction.
SSRI: Adverse Effects
GI upset, sexual dysfunction, insomnia, anxiety, headache, weight changes, and QT prolongation (especially with citalopram).
SNRI: Adverse Effects
Similar to SSRIs with additional risks of elevated BP and HR at higher doses (notably venlafaxine); GI distress and sexual dysfunction common.
Atypical Antidepressants: Bupropion
Dopamine/norepinephrine reuptake inhibitor; lowers seizure threshold; minimal sexual dysfunction; contraindicated in eating disorders.
Atypical Antidepressants: Mirtazapine
Increases NE and 5-HT via α2 antagonism; causes sedation, weight gain, increased appetite; fewer sexual side effects.
Antidepressants: Contraindications
MAOIs contraindicated with serotonergic drugs due to serotonin syndrome risk; TCAs avoided in suicidal patients due to overdose lethality.
1st vs. 2nd Gen Antipsychotics
FGAs (e.g., haloperidol): D2 blockade, higher EPS risk. SGAs (e.g., risperidone, olanzapine): D2 + 5HT2A blockade, lower EPS but higher metabolic risk.
Antipsychotics: MOA
FGAs block D2 receptors. SGAs block D2 and 5-HT2A receptors. Some SGAs also act on other receptors (α, histamine, muscarinic).
Antipsychotics: Adverse Effects
EPS (more common in FGAs), metabolic syndrome (SGAs), QT prolongation, sedation, orthostasis, prolactin elevation, and anticholinergic effects.
CYP450 & Antidepressants
Fluoxetine and paroxetine inhibit CYP2D6; fluvoxamine inhibits CYP1A2 and CYP2C19; drug interactions can impact efficacy and toxicity.
Multidrug Regimen Risks
Combining serotonergic agents increases serotonin syndrome risk; combining CNS depressants (e.g., BZDs + opioids) increases sedation and respiratory depression.
Depression: First- vs. Second-Line Agents
First-line: SSRIs, SNRIs. Second-line: atypical antidepressants (e.g., bupropion, mirtazapine), TCAs, and MAOIs (last-line due to safety).
Antidepressant Class Indications
SSRIs/SNRIs: depression, anxiety; TCAs: depression, pain; bupropion: depression, smoking cessation; trazodone/mirtazapine: depression + insomnia.
Benzodiazepines: MOA
Enhance GABA-A activity by increasing Cl- channel opening frequency; result in CNS depression, anxiolysis, sedation, anticonvulsant effects.
Benzodiazepines: Indications
Acute anxiety, panic disorder, alcohol withdrawal, seizure emergencies, muscle relaxation, pre-op sedation, short-term insomnia.
SSRI Withdrawal: General Considerations
Abrupt discontinuation can lead to SSRI discontinuation syndrome: flu-like symptoms, insomnia, imbalance, sensory disturbances, and hyperarousal. Tapering is essential to minimize symptoms.
