Sympathomimetics II: Examples of Synthetic Agonists Flashcards
What is oxmetazoline
its a sympathomimetic– a non selective alpha agonist and a synthetic
What are some other names for oxymetazoline?
generic, afrin, neo-synephrine 12 hour and many other over the counter nasal soultions
Whay is oxymetazolined used for?
its used for the short term treatment of nasal decongestion
relief of redness of the eyes from cold swimming and contacts
What are the formulations of oxymetazoline and what is important about these routes?
nasal: spray or drops
ophthalmic: drops
both route can lead to systemic absorption
What is the mechanism of action of oxymetazoline for nasal administration?
is the direct administration of alpha-receptors in the nasal mucosa-vasoconstriction; results in decreased blood flow and decreases congestion
What is the mechanism of action for ophthalmic administration?
the activation of alpha receptors- vasoconstriction in the arterioles of the conjunctiva; it result in decreased conjunctival congestion
What are the side effects of oxymetazoline?
headaches
nervousness
trouble sleepting
What side effects can nasal administration of oxymetazoline have on the body?
results in rebound congestion, buring of the nasal mucosa and sneezing
What effects does opthalmic administration of oxymetazoline have on the body?
results in rebound irritation, conjunctivitis with long term use
What are the drug interactions of oxymetazoline?
TCA- significant systemic absorption of oxymetazoline could lead to tachycarida and arrhythmias
What conditions are oxymetazoline contraindicated with?
heart disease, hypertension, and diabetes
What is phenylephrine?
its an alpha agonist; synthetic; sympathomimetic
What is are the other names for phenylephrine used to treat nasal congestion?
sinex, neo-synephrine- treatment of nasal congestion
What are neo-synephrine and neo-synephrine, relief?
neo-synephrine, relief: is used as a mydriatic (diagnostic) and conjuctival decongestant
neo-synephrine- usedd for acute hypotension and as an adjunt to local anesthesia
What are the nasal forms of phenylephrine and what is their duration of action?
spray or drops
duration of action is 30 min to 4 hours
How is opthalmic of phenylephrine administered and how long do its effects last ?
solution, effects occur within 30 min; last up to 3 hours
Where can phenylephrine be given or how is it dosed?
can be given IV, SC, and IM
What is the onset of action of IM and SC phenylephrine?
its 10-15 min
What is the onset of action of IV phenylephrine?
its immediate
How is phenylephrine metabolized?
its not broken down by COMT (because it has only one hydroxyls)—longer duration of action
What happens to the application of nasal and opthalmic routes when using phenylephrine?
can lead to systemic absorption
What is the mechanism of action of phenylephrine on nasal stuructures?
activation of alpha-1 results in vasoconstriction of the arterioles of the nasal mucosa
What is the mechanism of action of phenylephrine on the ophthalmics?
stimulation of alpha-1 receptors contracts the dilatory muscle of the pupil producing mydriasis. the alpha receptor activation constricts the arterioles of the conjuctiva to decreas congestion
What is the mechanism of action of systemic phenylephrine?
vasopressor-activates alpha-1 receptors to produce vasocontriction; an increase in total peripheral resistance occurs with an elevation in both systolic and diastolic blood pressure; the pressor effect leads to pronounced bradycardia via the vagus
What is the mechanism of action of phenylephrine with anesthetic adjunct?
constricts the vessels in the skin, mucous membranes and viscera (GI) via—alpha-1 receptor activation;
this decreases the rate of vascular absorption of the local anesthetics thereby prolonging their duration of action and decreasing the risk of to toxicity
What are the side effects of phenylephrine on the nasal structure?
its the same as oxymetazoline
What are the side effects of phenylephrine on opthalmics?
tachycardia, vomitting, tingling in the hands and feet and headache
What are the side effects of alpha-agonist on the CNS?
dizzinines
nervousness
restlessness
trembling
What
What is the inhalation anesthetics and phenylephrine?
increased risk of arrhythmias and senstization of the myocardium to sympathomimetics
What are the drug interactions beteween local anesthetics and phenylephrine?
may cut off blood flow to fingers and toes
What is the drug interaction between TCA and Cocaine + phenylephrine?
potentiation of the cardiovascular effects of these drugs manily tachycardia and arrhythmias
What is the drug interaction between phenylephrine and beta blockers?
unopposed alpha-receptor activity resulting in hypertension; inhibition of therapeutic effects
What is the drug interaction between digitalis and phenylephrine?
increased risk of arrythmias
What is the drug conbination between ergot dervatives and phenylephrine?
potentiated vascoconstriction, hypertension
What is the drug interaction between MAO inhibitors or phenylephrine?
potentiates and prolongs effects of phenylephrine; increased risk of hypertension and arrhythmias
What is clonidine?
its a selective alpha-2 agonist
What are some more commerical names for clonidine?
Oral; Catapres
generic, Transdermal; Catapres TTS
What is clonidine used for?
used for the treatment of hypertension, usually a step II addition or substitution
and treatment of hypertensive emergencies
What are the non-label uses of clonidine?
non-label uses include amelioration of nicotine and opiate withdrawal symptoms which are CNS mediated
How does the oral dose interact with the body?
the oral dose is well-absorbed duration of antihypertensive action is about 8 hours
Where is the clonidine transdermal patch located and what is its druation of action?
it is placed on the chest or upper arm–the drug is absorbed at a constant rate and the duration of action is between 7 dyas when the patch is presnent and for 8 hours folloing removal