Antidepressants

Question 0

What is the mechanism of action for TCAs?

Answer 0

Inhibition of neurotransmitter reuptake (serotonin and noradrenaline) by binding competitively to pre-synaptic neurone receptors (also act on muscarinic, acetylcholine and histamine receptors)

Question 1

Name 3 classes of antidepressant

Answer 1

• Tricyclics (TCAs)
• Monoamine Oxidase Inhibitors (MAOIs)
• Selective Serotonin Reuptake Inhibitors

Question 2

List the adverse side effects of TCAs

Answer 2

Sedation
Confusion
Motor inco-ordination
Weight gain

Question 3

How do you minimise the adverse effects of TCAs when starting a patient on them?

Answer 3

Titration them up slowly to build a tolerance

Question 4

What are the anti-muscarinic side effects of TCAs?

Answer 4

Blurred vision (dilated pupils)
Dry mouth
Constipation
Urinary retention

Question 5

How would someone present having overdosed on TCAs?

Answer 5

Tachycardic
SOB
Dry mouth
Dilated pupils

Question 6

How do TCAs cause postural hypotension?

Answer 6

Alpha 1 adrenoceptor blocking

Question 7

How do TCAs cause tachycardia (ventricular dysrhythmias and prolongation of the QT interval)?

Answer 7

Through vagal blockade

Question 8

What are the main contraindications for TCAs?

Answer 8

Prostatism
Recent MI
Narrow angle glaucoma
Heart Block
(Cautions inc. ischaemic heart disease; epilepsy)

Question 9

Name 3 drug types that TCAs interact with.

Answer 9

Other sedative agents (e.g. Opioids, anxiolytics, alcohol, sedative antihistamines)
Drugs the prolong the QT interval (e.g. Amiodarone)
Catecholamines and other sympathomimetics (e.g. Nor-/Adrenaline)

Question 10

Name 3 MAOIs

Answer 10

Phenelzine
Isocarboxazid
Tranylcypromine

Moclobemide (more preferable these days - safer)

Question 11

What is the mechanism of action for MAOIs?

Answer 11

Inhibit the Monoamine oxidase enzyme

Question 12

What are the 2 subtypes of MAOI and the substrate preference(s) for each?

Answer 12

MAO-A : preference for serotonin

MAO-B: preference for dopamine and phenylethylamine

Question 13

What are the main adverse effects if MAOIs?

Answer 13

Postural hypotension (sympathetic block)
Atropine-like effects (but less so than TCAs)
Weight gain
CNS stimulation (restlessness; insomnia; hallucinations)

Question 14

What must you advise patients to avoid when taking MAOIs?

Answer 14

Mature cheese Ephedrine-containing products (e.g. sudafed)
Beer. Pethidine
Game. Antidepressants (need dose titration)
Yeast/soy extracts
Pickled Herring

Question 15

Give 3 examples of Selective Serotonin Reuptake Inhibitors (SSRIs)

Answer 15

Fluoxetine
Paroxetine
Citalopram
Sertraline

Question 16

What are the most common side effects of SSRIs?

Answer 16

Nausea
Anorexia
Insomnia
GI disturbance
Loss of libido / failure to orgasm

Question 17

List some less common side effects of SSRIs

Answer 17

Hyponatraemia
GI bleeding
Serotonin syndrome (tremor, hyperthermia)
QT prolongation

Question 18

In which group of patients are SSRIs contraindicated? Why?

Answer 18

Under 18s. Risk of self harm and suicidal thoughts.

Question 19

SSRIs can cause hyponatraemia via SIADH (syndrome of inappropriate antidiuretic hormone).
What are the signs of hyponatraemia?

Answer 19

Dizziness
Lethargy 
Nausea
Confusion
Cramps.           Seizures

Question 20

What are the risk factors for hyponatraemia?

Answer 20

Old age. Reduced renal function
Female sex. Co-morbidity (diabetes, COPD, hypertension)
Low body weight
Low baseline sodium conc.
Concurrent drug treatment (e.g. NSAIDs, diuretics)

Question 21

What interactions can occur with SSRIs?

Answer 21

Drugs with increased GI bleed risk (antiplatelet, NSAIDs, corticosteroids)
Other antidepressants (particularly MAOIs)
Lowers seizure threshold

Question 22

Which antidepressant is considered most effective for the treatment of severe depression?

Answer 22

Venlafaxine (serotonin reuptake inhibitor with some noradrenaline reuptake at higher doses)

Question 23

In what way is Mirtazapine different to SSRIs?

Answer 23

No action on serotonin or noradrenaline reuptake. Enhance release of them from synapse.
Antagonist for presynaptic alpha-2 adrenoceptors

Question 24

With which antidepressant is there the greatest risk of suicide?

Answer 24

Venlafaxine

Question 25

Which particular antidepressant is being actively phased out? Why?

Answer 25

Dosulepin. Window between therapeutic benefit and fatal dose is narrow

Question 26

What is the average length of time it takes a prescribed antidepressant to start taking effect?

Answer 26

2-3 weeks

Question 27

A patient comes to see you, they are clearly suffering with depression, struggle to sit still and mention trouble sleeping. What would you prescribe.

Answer 27

Anxiolytic sedative antidepressants e.g. Amytriptyline or Mirtazapine

Question 28

A depressed patient comes to ask for some treatment for their depression. On examination she tells you she is always tired and has noticed a real reduction in her reaction time lately. What antidepressant would you prescribe?

Answer 28

SSRI or Imipramine (less sedative effect)

Question 29

A 65 year old gentleman is having difficultly following the death of his brother and recent split with his wife. In his history he tells you he suffering a heart attack 2 years ago. What antidepressant do you prescribe him?

Answer 29

Sertraline

Question 30

What is considered first-line treatment for depression?

Answer 30

SSRIs

Question 31

Can Fluoxetine be stopped abruptly?

Answer 31

Yes

Question 32

List some discontinuation symptoms

Answer 32

Flu-like. GI disturbances (SSRIs) Insomnia. Cardiac arrhythmia (TCAs) Vivid dreams. Mania Agitation Irritability

Question 33

Why can Paroxetine and Venlafaxine not be withdrawn abruptly?

Answer 33

Shorter half-life than other antidepressants

Question 34

What are the 2 types of benzodiazepines?

Answer 34

Hypnotics and Anxiolytics

Question 35

List some hypnotic benzodiazepines

Answer 35

Temazepam Nitrazepam (hangover effect) Z-related compounds (Zopiclone, Zopidem, Zaleplon)

Question 36

List some Anxiolytic benzodiazepines

Answer 36

Diazepam Lorazepam Oxazepam

Question 37

What is the mechanism of action for Benzodiazepines?

Answer 37

Benzodiazepine agonists Enhances inhibitory effect of GABA by opening chloride channels Binds to benzodiazepine sites on GABA (a) receptor Inhibition of neurotransmitters leads to sedation and reduction in anxiety

Question 38

In guidelines what is the only true indication for use of benzodiazepines?

Answer 38

Severe, disabling or distressing anxiety or insomnia | Short-term relief; 2-4weeks

Question 39

What are the major adverse effects of benzodiazepine?

Answer 39

Drowsiness and falls Impaired dexterity and judgement Forgetfulness, confusion, irritability, aggression, paradoxical dis-inhibition Dependence / Highly Addictive (withdraw cautiously)