Antidepressant drugs Flashcards
What are the different types of antidepressant drugs?
Tricyclic antidepressants (TCAs) Monamine oxidase inhibitors (MAOIs) Selective 5-HT reuptake inhibitors (SSRIs) Lithium ECT
What are the symptoms of depression?
Emotional: Misery, apathy and pessimism Low self-esteem Loss of motivation Anhedonia Biological: Slowing of thought and action Loss of libido Loss of appetite Sleep disturbance
What is unipolar depression/depressive disorder?
Mood swings in same direction
Relatively late onset
Drug treamtnet
What is reactive depression?
Depression in result to stressful life events- non-familial
What is endogenous depression?
Unrelated to external stresses
Familial pattern
What is bipolar depression/manic depression?
Oscillating depression/mania
Less common- early adult onset
Strong hereditary tendency
Drug treatment- lithium
What is the monoamine theory of depression?
Depression- functional deficit of central MA transmission
Mania- functional excess of NA and 5-HT
Based on pharmacological evidence
Biochemical evidence inconsistent
Delayed onset of clinical effect of drugs
Down regulation: alpha2, beta, 5HT receptors
What is the mechanism of action of TCA’s?
They are neuronal monoamine re-uptake inhibitors
Also have actions on alpha2, mAchRs, histamine and 5-HT receptors
Delayed down regulation of beta-adrenoceptors and 5-HT2 receptors
What are the pharmacokinetics of TCAs like?
Rapid oral absorption
Highly PPB
Hepatic metabolism- active metabolites- renal excretion (glucuronide conjugates)
Plasma t1/2- 10-20 hours)
What are the unwanted effects of TCAs at therapeutic levels?
Atropine like effects
Postural hypotension
Sedation
What will happen if someone overdoses on TCAs?
CNS: Excitement, delirium, seizures, coma, respiratory depression
CVS: Cardiac dysrhythmias, ventricular fibrillation/sudden death
What interactions do TCAs have with other drugs?
Many
PPB:TCA effects
Hepatic microsomal enzymes: TCA effects (neuroleptics, oral contraceptives)
Potentiation of CNS depressants (alcohol)
Antihypertensive drugs (monitor closely)
What are the two forms of MAOI?
MAO-A: NA and 5-HT
MAO-B: DA
How selective are most MAOIs?
Fairly non-selective
How do MAOIs have an effect?
They cause irreversible inhibition (long duration of action)
Rapid effects: Cytoplasmic NA and 5-HT
Delays effects: Clinical response- down regulation of beta-adrenoceptors and 5-HT2 receptors
What are the pharmacokinetics of MAOIs like?
Rapid oral absorption
Short plasma t1/2 but longer d.o.a
Metabolised in liver and excreted in urine
What are the unwanted effects of MAOIs including droog interactions?
Atropine like effects Postural hypotension Sedation Weight gain Hepatotoxicity Drug interactions Cheese reaction- tyramine containing foods and MAOI -> Hypertensive crisis (headache, b.p, intracranial haemorrhage) MAOIs and TCAs-> Hypertensive episodes MAOIs and pethidine -> Hyperpyrexia, restlessness, coma and hypotension
What is the mechanism of action of SSRIs?
Selective 5-HT re-uptake inhibition
What are the side effects for SSRIs like?
Less troublesome (but less affective against severe depression
What are the pharmacokinetics of SSRIs like?
p.o. administration
Plasma t1/2- 18-24 hours
Delayed onset of action- 2-4 weeks
What are the unwanted effects of SSRIs?
Nausea, diarrhoea, insomnia and loss of libido
Interact with MAOIs
Increase in suicidality
What is currently the most prescribed antidepressant drug?
Fluoxetine (prozac)- SSRI
What is venlafaxine?
Dose-dependent reuptake inhibitor
5HT -> NA -> DA
2nd line treatment for severe depression
What is mertazapine?
Alpha 2 receptor antagonist
Increased NA and 5HT release
Other R interactions (sedative)
Useful in SSRI intolerant patients
