Miscellaneous Drugs & Ganglionic Blockers Flashcards
What are the Alpha-2 Agonists?
- Clonidine
- GuanaBenz
- Guanfacine
- Methyldopa but its a prodrug
What happens with chronic activation of Alpha-2 and Beta-2 receptors?
Down regulation and loss of sensitivity to the Alpha-2 Agonist.
What complex/compund blocks the GRKs receptor complex formation?
Spinophilin
What happens when Beta-arrestins bind to phosphorylated Alpha-2 adrenoceptors?
This activates B-arr dependent signaling, these processes desensitize G protein signaling
What is the end result of B-arr binding?
The initiation of Alpha-2 adrenoceptor endocytosis
What are the Alpha-2 herteroreceptors?
Expression of the Alpha-2 receptor on Non-cholinergic tissue (Also presynaptic)
Where do Alpha agonist have most of their activity (Bradycardia, hypotension, sedation etc)
Alpha-2 heteroreceptors
How are the Bradycardia and hypotension achieved by the Alpha-2 agonists?
By activation of the parasympathetics especially the Vagal nerve system
What are the 2 functions of Alpha-2 Autoreceptors?
- Limit release of Norepi from sypathetic nerves
2. Limit release of Epi from Adrenal Chromaffin cells at rest
What is a requirement for an Alpha-2 agonist to be able to clinically lower BP?
Must cross the Blood Brain Barrier
What are the clinical effects of Alpha-2 Agonists?
- Parelled and Balanced drop in PVR and Systolic and Diastolic BP
- Withdrawal of SNS tone
- NO REFLEX TACHYCARDIA
- Decrease in Plasma renin activity
- Regression of Left Ventricular Hypertrophy
What are some of the Benefits of Alpha-2 agonists?
- Useful in Blocking reflex Tachycardia
2. No meaningful effect upon blood glucose or Lung function
Which two Alpha-Agonists are available by IV?
Clonidine and Methyldopa
Clonidine transdermal Patch
Which Alpha-2 Agonist has the Longes Half life?
Methyldopa Longest & Guanfacine Shortest
What spplement would chelate alphamethyldopa?
Iron supplements, suggested 2 hour gap between consumptions
What is indicated as a hazard in Methyldopa use?
Dose dependent renal Failure
Why is Alphamethyldopa contraindicated in Pheochromocytoma?
It interfers with catecholamine quantitation
What are the most complained about side effects of the Alpha-2 Agonists
- Somnolence
2. Dry mouth which increases likelyhood of caries, periodontal disease, and oral candidiasis
Which two Alpha-Agonist have the best profiles for use in pregnancy?
Methyldopa and Guanfacine
Which transporter does Reserpine inhibit?
VMAT2
What are the contraindications for Reserpine?
- Depression, increases suicidal tendencies
- Peptic ulcer dis or Ulcerative Colitis
- Pregnancy
- Breast feeding
What are the nicotinic postsynaptic receptors?
Ligand gated ion channels in the postsynaptic membrane
