This document discusses vasoconstrictor drugs used in dentistry including epinephrine, norepinephrine, and levonordefrin. It explains that vasoconstrictors decrease blood flow to the injection site, lower anesthetic blood levels, reduce risk of toxicity, increase duration of local anesthetics, and decrease bleeding. It provides details on the mechanisms and effects of different adrenergic receptors and considers the selectivity, potency, benefits and interactions of various vasoconstrictor drugs. The document also lists conditions where vasoconstrictor use should be avoided or minimized such as certain heart diseases.

1. R E Z A T A B R I Z I
A S S O C I A T E P R O F O R A L A N D
M A X I L L O F A C I A L S U R G E R Y
S H A H I D B E H E S H T I U N I V E R S I T Y O F
M E D I C A L S C I E N C E S
Pharmacology of
vasoconstriction drugs
Email:tabmed@gmail.com

2. Rule of vasoconstrictors
Decrease blood flow to the site of injection
Lower anesthetic blood level
Reduce risk of l/A toxicity
Increase duration of action of most L/A
Decrease bleeding in site of surgery

3. The adrenergic drug
β
β1
β2
α
α1
α2

4. α: mainly peripheral
β: mostly systemic

5. β1: receptor in heart ,increase heart rate via SA node
β2: locate in the vascular beds of skeletal muscle and
pulmonary vasculature : lead to vasodilation and
relaxation of the trachea
α1: in peripheral vasculature and cause sever
vasoconstriction of the peripheral art and vein
α2: mostly found in the CNS, lead to decreased
sympathetic outflow from brain and decrease in the
release of NE from the presynaptic neuron

6. α:mainly cause vasoconstriction at the peripheral
circulation , skin ,and mucous membranse , with a
nominal increase in the blood flow
β1: increase blood pressure
β2:decrease blood pressure

7. Vasocostrictor selectivity and potency

10. Epinephrine
Equal affinity for both α and β ,causing no dramatic
increase in blood pressure as a result of β2 activity
The vasodilatory β2 receptors are believed to be
more sensitive to low blood levels of epinephrine
than the vasoconsrictive α1 receptors
Small dose pf epinephrine often increase heart rate
and systolic blood pressure yet actually reduce
diastolic blood pressure with mean arterial pressure
remaining unchanged

11. Norapinephrine
Β1 properaties
Rebound bradycardia
Impair left ventricular diastolic function

12. levonordefin
Least potent caecholamines
Is most similar NE , less α1 but slightly β2 action
Patients with hypertension should not receive NE or
lenonordefrin

13. Potential benefits of vasocostictors
.IDecrease the clearance of the L/A
.IIReduced the total required amount
.IIIIncrease the duration and depth of anesthesia
.IVHemostasis
The presence of vasocostrictor also seems to be
benefical in patients with cardiovascular disease
because it reduces the release of reactionary
endogenous NE

14. Potential drug-drug interaction with vasoconstriction
MAO inh :interact with certain adrenergic drugs,
such as phenylephrine and ephedrine , which a
noncatecholamine structure.
TCA no reaction with epinephrine
Non selective β blocker ; reduce dose of epinephrine
and not used NE and levonordefrin

15. Felypressin
Synthetic analogue of the antiduretic hormone
vasopressin. nonsympathomimitic amine
It acts as a direct stimulant of vascular smooth
muscle .It actions appear to be more pronounced on
the vein than arterial
Contraindicate on pregnant patients

17. Conditions in which the use of vasoconstriction should be avoided
or minimized
Heart diseases:
BP >200/150
Unstable angina
MI under 6 mo
CVA under 6 mo
CABG under 6 mo
Uncontrol cardiac arrhythmias
CHF
Untreated hyperthyroidism
Sulfite –sensitive asthema

18. In patients with high risk epinephrine with
maximum dose of 0/04 mg and levonordefrin with
maximum dose of 0/2 mg is used