Week 9 Flashcards
What is an affective disorder
Characterised by disturbances in mood, associated with alterations in behaviour, energy, apetite and sleep.
Extremes range from mania to depressive states
eg. Bipolar, Depression, Anxiety
What are the major diagnostic criteria for depression?
- pervasive depressed mood and/or marked loss of interest in pleasure
along with 4 of the following:
- Marked change in weight
- Insomnia or hypersomnia
- fatigue/loss of energy
- Feeling worthlessness
- Excessive/inappropriate guilt
- indecisiveness or diminished concentration
- feelings of hopelessness
- thoughts of death, suicidal ideation
What is the monoamine theory of depression?
depression resulted from a decrease in activity of noradrenaline, serotonin in the CNS
What is an issue with the monoamine theory?
full antidepressant affect takes 6-8 weeks (some improvement seen in 1-3 weeks) but the drugs have an immediate effect on NA and serotonin
What are some of the treatments for depression?
- Psychotherapy (for mild to moderate depression)
- Cognitive behavioural therapy (eg hypnosis)
- improvement in socialisation, exercise and diet
- Electroconvulsive therapy
- Antidepressant medication
What is the goal of antidepressant pharmacology?
- provide relief from psychological and physiological symptoms
- enhance functional capacity
- reduce likelihood of self-harm or suicide
What % of adult patients respond to antidepressiant treatment (drugs)
half
30% with placebo.
Are antidepressant drugs equal in efficacy?
yes
What factors may influence the choice of antidepressants?
- the amount of sedation
- adjunctive drugs
- toxicity
- weight gain
What are some adverse effects of antidepressants?
- Serotonin toxicity can occur with just a single dose, resulting in hyperstimulation
- Most antidepressant drugs decrease threshold potential for seizures.
- in children has risk of increasing suicidal thoughts and behaviour - can work in adults too
- may provoke manic episode when used in people with bipolar
how do tricyclic antidepressants (TCA’s) work?
acts as an amine
- amine re-uptake pump
- stops neurotransmitters from being returned above synaptic cleft. Hang around in cleft longer. noradrenaline and serotonin
- keeps all neurotransmitters as it’s generalised. acts on all amine pumps
How are tricyclic antidepressants dangerous?
Most dangerous in overdose
- sedative
- autonomic side effects
what are autonomic side effects of Tricyclic antidepressants?
- include blocking of mAChR’s, histamine but more importantly SODIUM channel blocking.
Which has significant cardiovascular impact
What are the 3 signs of toxicity?
- Less than adequate perfusion
- QRS >0.12 (>0.16 indicates severe toxicity)
- QT prolongation (>1/2 R-R interval)
What are Selective Serotonin Reuptake Inhibitors (SSRIs)
- Works at the Amine reuptake pump but targets serotonin
What are some benefits of SSRIs?
Have a wide margin of safety and a different spectrum of side effects
Have fewer autonomic NS as lower effect of Noradrenaline
What are some disorder SSRI’s are prescribed for?
- Anxiety
- Panic
- OCD
- Bulimia nervosa
- premenstural dysphoric disorder
What are Monoamine Oxidase Inhibitors?
- Monoamine oxidase is an enzyme that breaks down neurotransmitters
- meaning more are left and less broken down
- works on both noradrenaline and serotonin
Why are Monoamine Oxidase Inhibitors used less often?
- dangerous interactions with some food and drugs
- hypertensive crisis common
What are some mood stabilisers?
Lithium - drug of choice
Mode of action unknown but it inhibits dopamine release
What is the therapeutic range for lithium?
is extremely low
0.5-1.2mmol
Where is emesis coordinated in the brain?
Vomiting centre in the medulla (medulla in brainstem)
Explain the Chemoreceptor trigger zone and its relationship to the vomiting centre
Chemoreceptor sits outside blood brain barrier, monitoring circulating toxins - triggers the vomiting centre
called chemoreceptor trigger zone
What nerve does the vomiting centre project to?
Vagus nerve… parasympathetic effects… and motor neurons supplying the abdominal muscles and coordinating emesis
