Vasoconstrictors Flashcards
Functions of vasoconstrictors (3)
Prolong duration of local anesthesia
Decrease likelihood of toxicity
Provide hemostatic effect
Groups of vasoconstrictors (3)
Pyrocathetic (epi & ne)
Benzol (levo)
Phenol (phenylephrine)
Mode of action of vasoconstrictors
are direct acting agents that attach directly to adrenergic receptors to produce sympathetic reactions
Adrenergic receptor that produce vasoconstriction when stimulated
alpha receptors
Adrenergic receptors that produce vasodilation when stimulated
beta receptor
beta receptor in the heart and small intestine
beta 1
beta receptor in the bronchi and vascular beds
beta 2, for bronchodilation
Vasoconstrictor drugs (5)
Epinephrine
Norepinephrine
Levonordefrin
Phenylephrine
Felypressin
Explain the rebound activity
excessive bleeding following use of epinephrine, vasodilation after vasoconstriction
Dominant effect of norepinephrine stimulates which adrenergic receptor
Alpha
Dominant effect of epinephrine stimulates which adrenergic receptor
Equal alpha and beta
at higher dose = alpha
at lower dose = beta
T/F. Epinephrine stimulates the CNS even below toxic levels
F. After toxic level is reached
Vasoconstrictor that increases blood glucose
Epinephrine
Dosage of epinephrine for healthy patients
0.2mg
Dosage of epinephrine for patients with cardiac problems
0.04mg
Dosage of norepinephrine for patients with cardiac problems
0.14mg
Dosage of norepinephrine for healthy patients
0.34mg
Tissue necrosis due to intense vasoconstriction
Ischemic effect
Vasoconstrictor associated with ischemic effect
norepinephrine
Dosage of levonordefrin for patients with cardiac problems
0.4mg
Dosage of levonordefrin for healthy patients
1mg
Dosage of phenylephrine for patients with cardiac problems
1.6mg
Dosage of phenylephrine for healthy patients
4mg
Dosage of felypressin
0.27 IU (9ml of 0.03 IU/ml soln)
Vasoconstrictor that mostly affect smaller blood vessels such as arterioles
levonordefrin
Vasoconstrictor associated with arteriolar constriction
levonordefrin
Least potent vasoconstrictor
phenylephrine
Most stable vasoconstrictor
phenylephrine
Vasoconstrictor similar to an antidiuretic hormone
felypressin
Nonsympathomimetic vasoconstrictor
felypressin
Contraindication of felypressin
preggers
Vasoconstrictor whose action is more pronounced in the venous microcirculation
felypressin
Termination of action of endogenous vasoconstrictors
reuptake in the blood stream and restorage in the adrenal medulla
Termination of action of exogenous vasoconstrictors (3)
- Deactivation by extraneuronal enzymes (Catechol-O-methyl-transferase)
- Uptake by the bloodstream
- Intraneuronal enzymatic destruction (monoamine oxidase/MAO)
Selection of vasoconstrictor is based on: (2)
Duration of desired effect
Physical condition of the patient
Potential drug interaction of vasoconstrictors (4)
- Tricyclic antidepressants
- MAO inhibitors (for hypertension and certain states of mental depression)
- Alpha blockers (phenothiazine, phentolamine, -osin hypertension meds)
- Beta blockers (-olol hypertension meds)
Systemic conditions that limit the use of vasoconstriction (5)
- Thyrotoxicosis
- Cardiovascular conditions (also a contraindication)
- Diabetes Mellitus
- Desire to produce hemostasis
- Concurrent Medication