Anti-Depressants

Question 1

Tricyclic antidepressants

Answer 1

Amitriptyline

TCAs block the re-uptake of noradrenaline and serotonin at nerve terminals

Depressive Disorder

• • TCAs no longer used much due to side effects & risk of OD (cardio-toxic). Do not need many tablets to OD – big limitation to TCAs
• • Less well tolerated than SSRIs
• • Side affects arise due to their affinity to bind to histamine and muscarinic ACh receptors.
• Histamine receptor binding leads to a sedated, hungover feeling.
• Alpha 1 noradrenergic receptor binding leads to postural hypotension, tachycardia, arrythmia
• Anti-cholinergic receptors lead to dry mouth, blurred vision, constipation, urinary retention
• Weight gain
• Compliance is reduced with such hefty side effects

Question 2

Selective Serotonin Re-uptake Inhibitors (SSRIs)

Answer 2

Fluoxetine
Citalopram
Escitalopram

Major Depressive Disorder
Generalized Anxiety Disorder (GAD)
Obsessive Compulsive Disorder (OCD)

GI upsets (nausea, vomiting, dyspepsia) 
- Headache 
- Sexual dysfunction
 - Insomnia? 
- Suicidal tendencies increased in the U25’s. 
-QT prolongation (-oprams)
*NO weight gain
Interactions: -St John’s Wort -Other antidepressants -They are CYP enzyme inhibitors and increase the levels of antipsychotics, benzodiazepines.

Question 3

Serotonin-Noradrenaline Reuptake Inhibitors (SNRIs)

Answer 3

Venlafaxine

Major Depressive Disorder
Also used in anxiety disorders, including social phobias

As with SSRIs, except with more adrenergic symptoms also:
-Increased sweating
-Agitation, anxiety
-Elevation of blood pressure @ high doses.
Interactions: -St John’s Wort -Other antidepressants -Metabolised by CYP2D6/34A