Mood Disorder Pharmacology Flashcards
Criteria for major depressive disorders
- Depressed mood for 2+ weeks
- Anhedonia
- Anxiety
- Disrupted sleep/appetite
- Cognitive deficits
- Loss of self-worth
- Suicidal thoughts
Co-morbid medical/psychiatric conditions with major depressive disorders
CAD, diabetes, stroke, chronic pain, drug abuse
Monoamine hypothesis
MDD caused by a deficiency in cortical/limbic 5HT, NE, DA
Two theories of depression that are non-mutually exclusive
the monoamine hypothesis and the neurotrophic hypothesis
Evidence for the monoamine hypothesis
- Reserprine (monoamine depleter) causes depression
- Dietary changes: patients treated with AD relapse when tryptophan is withdrawn from diet
- Genetics: SNPs in SERT associated with MDD
- 5HT, NE receptors are decreased in MDD patients
- 5HT/NE/DA agents work
Neurotrophic hypothesis
MDD is caused by loss of neurotrophic support and ADs restore neurogenesis and lost synaptic connectivity
Brain-derived neurotropic factor (BDNF) and neurons in a normal state
cell receives input from monoamine and BDNF stimulation, which supports neurotrophy and synaptic connectivity
BDNF and neurons in a depressed state
in part due to interference via glucocorticoids, BDNF is reduced and results in hypotrophy and loss of connectivity
BDNF and neurons in a treated state
monoamines result in increased CREB expression and results in resumption of normal BDNF secretion, re-gained connectivity
BDNF is critical for
neurotrophic support and required for the action of ADs
Evidence for the neurotrophic hypothesis:
- BDNF changes in MDD: stress/pain reduces BDNF, causing structural changes in hippocampus similar to that seen in MDD
- BDNF has AD properties: direct infusion of BDNF in rodent has AD effect
- ADs cause increased BDNF/neurogenesis
- Human MDD and BDNF: MDD associated with drop in BDNF
Why do antidepressants exhibit a delayed onset of several weeks compared to when their biochemical effects are thought to occur?
Time for monoamines to changes synthesis of BDNF, time for restored synaptic connectivity, and time for changes to occur such as up-or down-resgulation in signal transduction machinery
Antidepressant drug classes:
- SSRIs
- SNRIs (Serotonin-NE Reuptake Inhibitors)
- 5-HT2 Antagonists
- Tetracyclic/Unicyclic antidepressants
- MAOIs
SSRIs
- Fluoxetine (Proxac)
- Paroxetine (Paxil)
- Fluvoxamine (Luvox)
- Sertraline (Zoloft)
- Citalopram (Celexa)
- Escitalopram (Lexapro)
Which SSRIs inhibit P450s?
- Fluoxetine (Proxac)
- Paroxetine (Paxil)
- Fluvoxamine (Luvox)
What are SSRIs selective for?
more selective for SERT over NET
First choice for treatment of MDD due to safety and efficacy considerations
SSRIs
SSRIs Indications
MDD; Anxiety disorders; Premenopausal Dysphoric disorder; Eating disorders (bulimia only)
GAD
generalized, free-floating anxiety/undue worry
OCD
chronic anxiety-provoking thoughts (obsessions) and temporary anxiolytic actions (compulsions) taken to alleviate the anxiogenic thoughts
PTSD
anxious thoughts, hypervigilance from a traumatic event
Adverse effects of SSRIs
- Sexual dysfunciton
- Weight gain/loss
- Serotonin syndrome
- Adolescent suicide
- Withdrawal sndrome
- Effects on newborns
SSRI withdrawal
dizziness, paresthesias
Effects on newborns when mothers are on SSRIs
persistent pulmonary HTN (serious, fatal sometimes); withdrawal signs in infants; congenital malformations
Newer SNRIs
- Duloxetine (Cymbalta)
- Venlafaxine (Effexor)
- Desvenlafaxine (Pristiq)
Two classes of SNRIs
the older TCAs and a newer group of pure re-uptake inhibitors that hit NET with high affinity
Tricyclic Antidepressants (TCA)
- Amitriptyline (many receptors hit)
- Nortriptyline (secondary amine)
- Imipramine (anticholinergic)
- Desipramine (metabolite of imipramine)
- Clomipramine
Clinical use of TCAs
Used only in refractory MDD (not responsive to SSRIs)
Indications of SNRIs
Refractory MDD; anxiety disorders; pain (diabetic neuropathy, fibromyalgia); enuresis (bed wetting); insomnia
Adverse effects of SNRIs (most apply to the TCAs)
- Cardiotoxicity
- Sexual dysfunction
- Weight loss
- Serotonin syndrome (TCA and MAOI co-admin)
- Suicidal thoughts
- Withdrawal syndrome
- Sedation
Cardiotoxicity from SNRIs
derives from the ability to block voltage gated sodium channels in the heart, plus the anticholinergic properties as well; high BP, ventricular arrhythmias
5HT2 Antagonist
Trazodone
Patients on trazodone should avoid
grapefruit juice as it blocks CYP3A4, the same CYP that metabolizes trazodone
Bupropion
unicyclic antidepressant; DA and NE reuptake inhibitor; no 5HT systemo activity; nAchR antagonist activity
Adverse effects of Buproprion
few sexual side effects, some insomnia, anorexia, agitation, seizures
Use of Buproprion
AD, mood enhancer, smoking cessation
Mirtazapine
tetracyclic antidepressant; mixed antagonist or inverse agonist activity at 5HT, alphaAR, histamine, mACh, DA, NET, DAT, and SERT; stimulates release of NE and 5HT yet blocks 5HT receptors
Adverse effects of Mirtazapine
few sexual, sedative (histamine), low cardio risk
Use of Mirtazapine
refractory MDD, other mood disorders
Monoamine Oxidase Inhibitors
- Selegiline (MAO-b, irreversible)
- Tranylcypromine (non-selective, irreversible)
- Phenelzine (non-selective, irreversible)
MAO Type A
found in monoamine-expressing neurins in the CNS
MAO Type B
found in DA neurons and in cells that need to break down phylethylamine and other trace amines
When would you use MAOIs
used in cases of refractory MDD
Adverse effects of MAOIs
orthostatic hypotension, sexual dysfunction, and CNS stimulant-like properties
TCA overdose
mainly a cardiovascular event, such as arrhythmia and BP changes, but also includes CNS activation, anticholinergic effects and seizures
TCA overdose treatment
usually directed toward the cardiovascular symptoms
MAOI overdose
characterized by a hyperadrenergic state, including psychosis, confusion, fever and seizures
MAOI overdose treatment
cardiac monitoring, HCO3
5HT syndrome
A poisoning due to overstimulation of 5HT receptors - not an idiosyncratic drug reaction; likely in central gray nuclei/medulla in brain stem, likely 5HT2A
Severe side effects of 5HT syndrome
delirium, coma, hypertension, tachycardia, diaphoreses, clonus, hyperreflexia, tremor, akathisia (agitation, restlessness)
How do you prevent serotonin syndrome?
stop other ADs 2-4 weeks prior to starting MAOI (fluoxetine in particular); stop MAOI at least 2 weeks prior to starting/switching to SSRI (or other 5HT agent)
What is the Tyramine Effect
MAOI prevents tyramine breakdown in the gut; tyramine builds up in the serum and acts as a peripheral only catecholamine releasing agent; noradrenergic effects are enhanced
What is a bad combination with non-selective MAOIs
Tyramine-rick foods (meat, cheese, dairy, many others)
Result of the Tyramine Effect
malignant hypertension, stroke, MIs
Prevention of the Tyramine Effect
low-tyramine diet, use MAO-B inhibitor, use reversible MAOIs, avoid other sympathomimetics (pseudoephedrine, phenylpropanolamine) combined with MAOIs
Herbal Antidepressants
St. John’s Wort (Hypericum perforatum plant)
MOA of St. John’s Wort
monoamine reuptake block though some uncertainty exists
Defining feature of bipolar disorder
Mania
Symptoms of mania
hyperactivity, impulsive, disinhibition, aggression, less sleep, psychosis, cognitive impairment
Bipolar I
extreme manic episodes; depressive episodes; recurring; rapid cycling (>4 per year); more severe
Bipolar II
hypomanic episodes; depressive episodes often dominant; some functionality during hypomania; less severe
Drug classes for Bipolar Disorder
Lithium carbonate
Atypical antipsychotics
Antiepileptics
Benzodiazepines
First-choice drug for bipolar
Lithium carbonate
Atypical antipsychotics
Aripiprazole, olanzapine, paliperidone, quetiapine, risperidone, ziprasidone, (clozapine)
Antiepileptics
Carbamazepine, valproate, (levetiracetam, primidone, zonisamide)
MOA for lithium
largely unknown and highly speculative; may be inositol depletion which may alter signaling systems or change plasticity; may be from inhibition of GSK-3
What must you monitor with lithium
- plasma lithium levels
- Diuretic usage
- Sodium in diet should be consistent
- Exercise
Why must you follow diuretic usage with lithium
diuretics can reduce the clearance of lithium, which would require the dose of lithium to be lowered
Hallmark feature of lithium side effects
tremor which can be treated with a beta blocker
Side effects of lithium
tremor, low thyroid fxn, edema, arrhythmias
Lithium overdose
cognitive disturbances, GI issues, ataxia, nystagmus, slurred speech, muscle spasms
What has replaced lithium in chronic treatment of bipolar
anticonvulsants
What are antipsychotics/benzodiazepines used for
severe mania
1st line maintenance therapy for bipolar disorder
Lithium (plus benzo in severe); Lamotrigine; Risperidone
2nd line maintenance therapy for bipolar disorder
aripiprazole, quetiapine, olanzapine; and valproate
Other options for maintenance therapy for bipolar disorder
carbamazepine, combination therapy