Pharmacology - antidepressants

Question 1

SSRIs mechanism of action

Answer 1

Increase serotonin activity by reducing the presynaptic reuptake of serotonin after release

Question 2

Common side effects of SSRIs

Answer 2

Restlessness and agitation on initiation

Last for few weeks:

• Nausea and GI disturbance
• Headache

Long term:

• Weight changes
• Sexual dysfunction
• Bleeding
• Suicidal ideation - more energy but bleak outlook

Question 3

Examples of SSRIs

Answer 3

Sertraline
Citalopram
Fluoxetine - give to under 25’s
Paroxetine

Question 4

Cautions for specific SSRIs

Answer 4

Sertraline - safest in cardiac disease
Citalopram - Long QTc syndrome especially with antipsychotics
Fluoxetine - serotonin syndrome (long half-life)
Paroxetine - discontinuation syndrome (short half -life)

Question 5

Use of SSRIs

Answer 5

Antidepressant used in depression and anxiety

Question 6

SNRI method of action

Answer 6

Act in the same way as SSRIs plus binds to noradrenaline reuptake receptors as well

Question 7

SNRI use

Answer 7

Neuropathic pain

Question 8

SNRI side effects

Answer 8

Same as SSRIs but more likely to have sedation, nausea and sexual dysfunction

Question 9

SNRI examples

Answer 9

Duloxetine - low dose

Venlafaxine - greater efficacy and can use higher doses

Question 10

Venlafaxine cautions

Answer 10

Caution with heart disease

Monitor BP at higher doses

Question 11

Mirtazapine mechanism of action

Answer 11

Acts of 5HT-2 and 5HT-3 antagonist

Strong histamine activity - sedation

Question 12

Mirtazapine side effects

Answer 12

Sedation

Weight gain

Question 13

TCA use

Answer 13

Low dose - neuropathic pain

High dose - second-line antidepressant if SSRI’s not tolerated

Question 14

TCA side effects

Answer 14

Muscarinic side effects
Histaminic side effects
Long QTc syndrome and arrhythmias

Question 15

Monoamine oxidase inhibitors types

Answer 15

MAOI A - serotonin receptors
MAOI B - dopamine receptors

Irreversible and reversible

Both can potentially increase adrenaline

Question 16

Uses of MAOI

Answer 16

Used as an adjunct to increase the effectiveness of SSRIs

Effective for atypical depression

Question 17

Examples of MAOI

Answer 17

Irreversible - more dangerous

• Phenelzine
• Isocarboxazid

Reversible - less dangerous

• Moclobamide
• Tranylcypromine

Question 18

Side effects of MAOI

Answer 18

Tyramine reaction - hypertensive crisis
- avoid amino acids in cheese, pickled meats, wine

If changing to another antidepressant, needs a washout period of up to 6 weeks

Question 19

Vortioxetine features

Answer 19

Serotonergic agonist and antagonist

• effective
• well-tolerated
• used to treat cognitive symptoms

Question 20

Monitoring on antidepressants

Answer 20

Measure weight before antidepressants

Question 21

Anti muscarinic side effects

Answer 21

Dry Mouth 
Palpitations
Difficulty swallowing 
Thirst 
Urinary retention 
Hot and flushed skin 
Dry skin

Question 22

Histamine side effects

Answer 22

Dry mouth
Drowsiness
Dizziness
Nausea and vomiting

Question 23

Discontinuation syndrome

Answer 23

Antidepressants are not addictive but there can be withdrawal symptoms

• sweating
• agitation and tremor
• insomnia
• headaches
• nausea and vomiting
• clonus
• paraesthesia
• increased mood change

Shorter half-life, bigger problem

Question 24

How to minimise discontinuation syndrome

Answer 24

• Alternate days of taking and not taking
• Take half tablets
• Can switch from paroxetine to fluoxetine before reducing

Question 25

Serotonin syndrome features

Answer 25

Cognitive - headaches, agitation, hypomania, confusion, coma

Autonomic - shivering, sweating, hyperthermia, tachycardia, nausea and diarrhoea

Somatic - myoclonus, hyper-reflexia and tremor

Question 26

Treatment of serotonin syndrome

Answer 26

Fluids and monitoring

Question 27

Cause of serotonin syndrome

Answer 27

SSRI + MAOIs

Question 28

How to prevent serotonin syndrome

Answer 28

Give a 14 day SSRI washout period before starting MAOIs

Question 29

Antidepressant interactions

Answer 29

NSAIDs - increased risk of bleeding

Other antidepressants - serotonin syndrome

Carbamazepine, diuretics - hyponatraemia

Question 30

How to withdraw from antidepressants

Answer 30

Withdraw slowly for at least 4 weeks to reduce the severity of discontinuation syndrome