What are the unwanted effects of MAOi?
Atropine-like effects (< TCAs) Postural hypotension (common) Sedation (Seizures in OD - long term use can lead to drowsiness) Weight gain (possibly excessive, which would lead to termination of treatment) Hepatotoxicity (hydrazines; rare)
What are the drug interactions of MAOi?
What are SSRIs, MoA and their structures?
Selective 5-HT re-uptake inhibition
Less troublesome side-effects;
safer in o.d.
But less effective vs severe depression
What is the pharmacokinetics of SSRIs?
p.o. administration Plasma t1/2 (18-24 hrs) Delayed onset of action (2-4 weeks) Fluoxetine competes with TCAs for hepatic enzymes (AVOID COADMIN)
What are the unwanted effects of SSRIs?
Nausea, diarrhoea, insomnia & loss of libido Interact with MAOIs (avoid co-administration) ↑ Suicidality (< 18 years old) Fewer than TCAs/MAOIs Fluoxetine (‘Prozac’): currently most prescribed antidepressant drug -> side effect profile is superior, but the effects are the same
What is Venlafaxine?
Dose-dependent Reuptake inhibitor 5HT > NA > DA 2nd Line treatment for severe depression
What is mertazapine?
α2 Receptor antagonist; ↑ NA & 5HT release; Other R interactions (sedative); Useful in SSRI-intolerant patients
How do inhalational GA reduce neuronal excitability?
TREK (background leak K channels) -> tend to hyperpolarise neurones, leading to reduced neuronal excitability -> inhalation agents facilitate the opening of these channels then you will get enhanced hyperpolarisation, which is important in suppression of reflex responses
What are the characteristics of a good GA?
LOW blood:gas partition coefficient, so effects come on very fast, very easy to control; once GA removed from lungs, then effects on brain will go very quickly
What is the difference between inhalational and intravenous GAs?
Airway irritation can lead to cough reflex initiated
Which GAs can you use in each type of clinical setting?