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39 Cards in this Set
- Front
- Back
What are vasoconstrictors?
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an agent that causes narrowing the blood vessels.
prolong and increase the depth of anesthesia reduce the toxic effect of the drug render the area of injection with less bleeding decrease blood flow to the site of injection |
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Describe the chemical structure of vasoconstrictors
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chemically identical or quite similar to the sympathetic nervous system mediators epinephrine and norepinephrine
resemble the response of adrenergic nerves to stimulation and they are classified as sympathomimetic, or adrenergic. |
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What makes a vascoconstrictors sympathomimetic?
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Based on whether or not is has a cathecholamine. if they have amine attached to aliphatic chain, they are called cathecolamines
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Name some catecholamines..
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Epi, Norepi, levonordefrin, isoproterenol, dopamine
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What are some noncatecholamines
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amphetamine
ephedrine phenylephrine |
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Direct acting drugs vs. indirect
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-exert their action directly on adrenergic receptors
indirect: release cathecholamine NE from adrenergic nerve terminals (tachyphylaxis) |
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Direct acting drug names
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Epinephrine
Norepinephrine Levonordefrin Isoproterenol Dopamine Methoxamine Phenylephrine |
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Indirect acting drugs
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Tyramine
Anphetamine Methamphetamine Hydroxyamphetamine |
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Mixed action drugs
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Metaraminol
Ephredine |
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What happens if you activate alpha receptor by a sympathomimetric drug?
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produces a response that includes the contraction of smooth muscle in vessels (vasoconstriction).
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What happens if you active beta receptor? B1 and B2?
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Activation of receptors produces smooth muscle relaxation (vasodilatation and bronchodilatation) and cardiac stimulation.
1 stimulates the heart 2 produces bronchodilatation and vasodilatation |
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Describe the end effect of stimulating alpha and beta receptors by epinephrine
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alpha: increase systolic and diastolic pressure
beta: vasodilation or bronchodilation with a beta blocker: vasodilation and bronchodilation does not occur |
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What affect predominates with a low dose epinephrine? high dose?
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for low dose, Beta effects predominate so you get vasodilation.
for high dose, alpha effects predominate |
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Describe teh cardiovascular dynamics of epiephrine
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Increased systolic and diastolic pressures
Increased cardiac output (CO = HR X SV) Increased stroke volume Increased heart rate Increased strength of contraction Increased myocardial oxygen consumption |
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Describe the respiratory system effects of epinephrine
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Is a potent dilator (2 effect) of the smooth muscle of the bronchioles.
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Describe the termination of action and elimination of epinephrine
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Reuptake by adrenergic nerves ** most commonly done.
Inactivated in the blood by the enzyme catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), both of which are present in the liver. |
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What else do we use epinephrine for in the clinic?
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acute allergic reactions
bronchospasm cardiac arrest vasoconstrictor for hemostasis vasoconstrictor for local anesthetics to produce mydriasis |
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Max amt of epinephrine you can give to someone for a normal healthy patient..?
Patient with clinically sig cardiovascular disease? |
0.2 mg per appointment
concentration may be dependent on whether you want hemostasis. ex: 1/50,000 may be better in hemostasis vs. 1/100,000. Cardiac disease: 0.04 mg per appt. |
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Side effects and overdose of epinephrine..
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CNS stimulation
increases fear, anxiety, tension, restlessness, headache, tremor, weakness cardiac dysrhythmias Increased systolic and diastolic pressures angina |
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Norepinephrine (Levarterenol)..
Chemical properties |
Is relatively stable in acid solution, deteriorating on exposure to light and air.
Acetone-sodium bisulfite is added to retard deterioration (preservative) Is available in both synthetic and natural forms. Actions are 90% receptors and 10% . Mostly used in different parts of the world, but not here. |
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Systemic actions of NE: cardiovasc. dynamics
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Decreased heart rate
Increased systolic pressure Increased diastolic pressure Unchanged or slightly decrease cardiac output Increased stroke volume Increased total peripheral resistance not as good as epinephrine to activate alpha. |
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NE: respiratory system actions
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Does not relax bronchial smooth muscle as does epinephrine.
It is not clinically effective in the management of bronchospasm. |
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NE: termination of action and elimination
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Reuptake at adrenergic nerve terminals and its oxidation by MAO. Exogenous norepinephrine is inactivated by COMT.
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Clinical applications of NE
What are the max doses of NE in a normal healthy patient? |
It is used as a vasoconstrictor in local anesthetics and for the management of hypotension
0.34 mg per appt cardiac pat: 0.14 mg |
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What are the cardiac alterations after injection of 2% lidocaine with NE 1/50,000
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increase in SBP, DBP, and MAP, and decrease in HR.
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Levonodefrin - Neo-Cobefrin: chemical properties. Max dose?
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Synthetic vasoconstrictor
Direct receptor stimulation (75%) with some activity (25%) Systemic actions similar to epinephrine, but to a lesser degree Maximum Dosage: 1 mg per appointment 20 ml of a 1:20,000 dilution (11 cartridges) Obtain with Mepivacaine 2% with Levonodefrin 1: 20,000 dilution |
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Neo-synephrie (phenylephrine hydrochloride)
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Phenylephrine is quite soluble in water.
It is the weakest vasoconstrictor used in dentistry. Direct receptor stimulation (95%). Exerts little or no action on the heart. |
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Cardiovascular actions of phenylephrine hydrochloride
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Cardiovascular dynamics:
Increased systolic and diastolic Reflex bradycardia Slightly decreased cardiac output Rarely associated with provoking cardiac dysrhytmias |
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1. Pheylephrine hydrochloride. resp system
2. termation 3. side effects and overdose |
Respiratory system:
Bronchi are dilated but to a lesser degree. Is not effective in treating bronchospasm. Termination of action and elimination: Undergoes hydroxylation to epinephrine, and then follows a similar pattern as epinephrine. Side effects and overdose: CNS effects are minimal Headache and dysrhythmias have been noted following overdose. |
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Phenylephrine HCL clinical apps..
max dose? |
Vasoconstrictor in local anesthetics
Management of hypotension Nasal decongestant Ophthalmic solutions to produce mydriasis Max dose: 4 mg per appt for healthy pt ASA III or 4: 1.6 mg |
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Felypressin (octapressin) chemical characteristics
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Is a synthetic analogue of the antidiuratic hormone vasopressin
It acts as a direct stimulant of vascular smooth muscle. Its action appears to be more pronounced on the venous microcirculation. No direct effects on the myocardium |
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What factors must be considered in selecting a vasoconstrictor
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the length of the dental procedure
the need for hemostasis during and following the procedure. the requirement for post operative pain control medical status of the patient |
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Wht are some relative contraindications for epinephrine?
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Patients with more significant disease.
Patients with certain noncardiovascular diseases (such as thyroid dysfunction, diabetes, sulfite sensitivity). Patients receiving MAO inhibitors, tricyclic antidepresants and phenothiazines. |
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OraVerse (phentolamine mesylate)
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Indicated for the reversal of soft-tissue anesthesia and the functional deficits resulting from an intraoral submucosal injection of a local anesthetic containing a vasoconstrictor
It is not recommended for use in children less than 6 years of age or weighing less than 15 Kg. can either do infiltration or block injection. 1/2 cartiage is equal to 0.2 mg. 0.4 mg/ 1.7 ml soln per cartridge |
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What are some warnings and precautions for oraverse
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MI, cerebrovascular spasm, and cerebrovasular occlusion have been reported to occur following the parenteral administration of phentolamine. The events occurred in association with marked hypotensive episodes producing shock-like states.
tachycardia, arrythmias may occr |
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Mechanism of action for OraVerse
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Produces an alpha-adrenergic block of relatively short duration resulting in vasodilation when applied to vascular smooth muscle
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What may occur with epinephrine towards the latter end of the dental procedure?
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The concentration will decrease and the beta affects (vasodilation) will dominate over alpha affects (vasoconstriction). This leads to increase post operative blood loss and may compromise a patient's cardiovascular status.
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What is an advantage with phenylephrine over epinephrine in terms of application during the dental procedure?
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Phenylephrine does not have any beta effects and is a pure vasoconstrictor. This is longer acting than epinephrine. However, it is a weaker vasoconstrictor than epinephrine so even though it has a longer duration, hemostasis during the procedure isn't as effective. but post operative bleeding passes with less bleeding.
We must note that phenyephrine is not included with any dental cartridge. |
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What vasoconstrictor constricts venous circulation more than arterial circulation?
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Felypressin. It is of minimal value for hemostasis during a procedure and is not in dental cartridges.
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