Pharm - pharmacology of depression Flashcards
the seven step process
- identify the patient’s problem
- Specify the therapeutic objective
- Select a drug on the basis of:
- comparative efficacy
- safety
- cost
- suitability - Discuss choice of meds with patient and carer and make a shared decision about treatment
- Write a prescription
- Counsel patient on appropriate use of medicine
- Make appropriate arrangements for follow up
how does angiotensin 2 receptor agonist raise bp?
Angiotensin II acts on the adrenal cortex, causing it to release aldosterone, a hormone that causes the kidneys to retain sodium and lose potassium.
-> Elevated plasma angiotensin II levels are responsible for the elevated aldosterone levels present during the luteal phase of the menstrual cycle.
What questionnaire can be used to diagnose depression?
PHQ-9
Why are SSRIs first line treatment for depression?
- typically have less side effects
Mechanism of action of SSRIs?
- they stop reuptake of serotonin
Most common SSRIs?
- sertraline
- citalopram
- fluoxetine
- fluvoxamine
- escitalopram
what effect do erythromycin and citalopram do on an ECG?
prolong QT interval
- > this is a severe interaction- can lead to torsades de pointes
- > don’t give to someone on antihypertensives
what’s a problem with SSRIs?
- Side effects can present before benefits
- slow acting so takes 4-6 weeks for an effect
Problem with SSRIs?
- the increase in positive effects is relatively small
- increase in side effects can be exponential
- got to get the dose right
Why do you taper off drugs when you stop taking them?
Give an example of drugs we have to do this for?
- to avoid withdrawal
- Sertraline and citalopram and venlafaxine
venlafaxine targets:
serotonin transporter (mood, personality, wakefulness) noradrenaline transporter (emotions, cognition) SNRI (serotonin noradrenergic reuptake inhibitors)
Venlafaxine works by increasing serotonin levels, norepinephrine, and dopamine in the brain by blocking transport proteins and stopping its reuptake at the presynaptic terminal.
mirtazipine (receptor antagonist) targets:
- alpha 2 receptors (Antidepressant effect)
- It blocks alpha 2 autoreceptors in noradrenergic neurons and alpha 2 heteroreceptors in serotonergic neurons.
- This means that when mirtazapine blocks alpha 2 receptors it blocks the inhibitory signal, which increases norepinephrine release to the synaptic cleft. - histamine H1 receptor (less vasodilation and sedation-> sleepiness)
- 5HT2A receptor (blocks serotonin binding- anti-depression effect)*
- 5HT3A receptor (blocks serotonin binding- antiemetic effect))*
*This means more serotonin binds to 5HT1A (related to depression)
what does noradrenaline do the the heart?
increase HR by beta 1
beta-1 receptor in the heart increases sinoatrial (SA) nodal, atrioventricular (AV) nodal, and ventricular muscular firing, thus increasing heart rate and contractility.
what does noradrenaline do to blood vessels?
constricts via alpha 1
“Blood vessels with α1-adrenergic receptors are present in the skin, the sphincters of gastrointestinal system, kidney (renal artery) and brain”
do antagonists have efficacy?
no - its an antagonist
what offsets anti-histamine activity of mirtazipine?
noradrenergic effect (at higher doses)
What are the two classes of MAOIs and what are the difference?
Non-selective monoamine oxidase inhibitors - targets MAO A and MAO B- increases dopamine, noradrenaline and serotonin
Selective monoamine oxidase inhibitor - targets MAO B only- increases dopamine only (often used to treat parkinson’s)
What’s the problem with non-selective MAOIs?
Have many side effects
Bind irreversibly to the enzymes