pharmacology of depression

Question 1

SSRI primary mechanism of action

Answer 1

Inhibition of serotonin reuptake results in an accumulation of serotonin. Serotonin in the central nervous system plays a role in the regulation of mood, personality, and wakefulness.

Question 2

SSRI primary target

Answer 2

serotonin transporters

Question 3

Main side effects of SSRIs

Answer 3

GI effects (nausea, diarrhoea), sexual dysfunction, anxiety, insomnia

Question 4

What does sertraline cause mild inhibition of

Answer 4

dopamine transporter

Question 5

How must SSRIs be discontinued

Answer 5

gradually

Question 6

What does sertaline partially inhibit at high doses

Answer 6

Partial inhibition of CYP2D6 at high doses (150 mg).

Question 7

What does citalopram mildly antagonise

Answer 7

muscarinic and histamine (H1) receptors

Question 8

Citalopram metabolised by

Answer 8

CYP2C19.

Question 9

fluoxetine has complete inhibition of what

Answer 9

CYP2D6

Question 10

fluoxetine has partial inhibition of what

Answer 10

CYP2C19

Question 11

What other drug should fluoxetine be used cautiously with

Answer 11

warfarin

Question 12

what type of anti depressant is venlaflaxine

Answer 12

SNRI

Question 13

Main drug targets of venlaflaxine

Answer 13

serotonin transporter

noradrenaline transporter

Question 14

Primary mechanism of venlaflaxine

Answer 14

Venlafaxine is a more potent inhibitor of serotonin reuptake than norepinephrine reuptake.

Noradrenaline in the central nervous system is implicated in the regulation of emotions and cognition.

Question 15

How must venlaflaxine be discontinued

Answer 15

gradually

Question 16

Side effects of venlaflaxine

Answer 16

GI effects (nausea, diarrhoea), sexual dysfunction, anxiety, insomnia, hypertension (at higher doses)

Question 17

Mirtazapine mechanism of action

Answer 17

Antagonises central presynaptic alpha-2-adrenergic receptors, which causes an increased release of serotonin and norepinephrine.

Antagonises central 5HT2 receptors, which leaves 5HT1 receptors unopposed causing anti-depressant effects.

Question 18

Mirtazapine targets

Answer 18

Alpha-2 receptor



5-HT2 receptor

Question 19

Side effects of mirtazapine

Answer 19

Low probability of sexual dysfunction. May exacerbate REM sleep behaviour disorder
Weight gain, sedation

Question 20

Screening tool GPs can use for depression

Answer 20

Patient Health Questionnaire 9

Question 21

Why should citalopram and erythromycin not be prescribed together

Answer 21

both increase QT interval

Question 22

Why does SSRI effectiveness plateau eventually

Answer 22

SSRIs block serotonin reuptake but at 1 point all the available serotonoin reuptake transporters are blocked so there’s no point increasing dose

Question 23

When do the adrenergic effects of venlaflaxine occur

Answer 23

Adrenergic effects of venlafaxine appear with doses administrated more than 150 mg/day, apparent increase in blood pressure and increased heart rate are observed when the daily dose exceeds 300 mg

Question 24

Describe mirtazapine drug targets from highest to lowest affinity

Answer 24

Histamine (H1) receptor - sedation
alpha 2 receptor - anti depressant
5HT2 receptor - antagonism
5HT3 receptor - anti emetic

Question 25

Why is mirtazapine’s sedative effects decreased at high doses

Answer 25

At low doses, mirtazapine preferentially blocks the histamine receptor, since at lower plasma concentrations it has a higher affinity to histamine receptors than to serotonergic receptors. Consequently, there is increased duration of sleep at low plasma concentrations and increased sedation at low doses of mirtazapine. At higher doses, the antihistamine activity is offset by increased noradrenergic transmission, which reduces its sedating effect

Question 26

Caution when switching anti depressants

Answer 26

Caution is required when switching from one antidepressant to another due to the risk of drug interactions, serotonin syndrome, withdrawal symptoms, or relapse.
Washout required before starting new drug