Unit 4 Flashcards
What is the therapeutic action of a vasoconstrictor?
- decreases absorption into the bloodstream to prevent solution being carried away from the site
- increases the duration
- decreases the toxicity
- decreases risk of bleeding
What should be considered when selecting LA?
- the duration of pain control based on the length of procedure for soft tissue and pulpal
- the need for post operative pain control
- the patient’s health history including medication
- any local anesthetic, sodium bisulphite or metabisulphit allergy
- the need for haemostasis
How are LA agents categorized?
into short, intermediate, long acting
all marked with a unique color
What are the properties of Lidocaine?
- amide
- potent vasodilator (used in cardiac emergencies)
- short: intermediate acting
- low risk of allergy (no documented reactions)
- has anticonvulsant properties initial signs of CNS overdose likely more depressive
- metabolized in the liver, excreted by kidneys
- injectable and topical
- safest for pregnant women
- pKa 7.7
- pH 3.3-5.5
- MRD 7.0 mg/kg and 500mg
- available as a topical (to be used when esters are contraindicated, pregnant)
- 2% with 1:50,000epi - hemostasis during surgery
- 2% with 1:100,000 epi pulpal 1.5hrs, soft tissue 3-5hrs
- without epi: short acting
- with epi: intermediate acting
- onset 2-3 mins
- half life: 96 mins
What are the properties of mepivacaine
- Less vasodilation than lidocaine therefore effective without epi
- Injectable only not effective as topical
- Pulpal anesthesia of 20-40 min, 2-3 hrs soft tissue
- Equal in potency to lidocaine 2/3 Articaine
- Metabolized in the liver, excreted by the kidney(16% unchanged)
- pKa is 7.6 pH 4.5-6.8 (higher pH can be more effective in areas of infection)
- MRD 6.6 mg/kg 400mg
- Onset 1.5=2 min
- half life 1.9 hrs longer than lidocaine
What are the properties of prilocaine?
- not injected at CC/in Oraqix
- Equal potency to lidocaine, 2/3 as potent as Articaine
- Less toxic that lidocaine
- Less vasodilation than lidocaine more than mepivicaine
- 4% solution 40-60 min pulpal anesthesia, 2-4 hours of tissue anesthesia
- More easily metabolised by liver, excreted by kidneys (least toxic therefore good for medically compromised with minimal effects on the CNS and CVS
- Integral part of EMLA can penetrate tissue well (topical preparation for skin)
- Risk of methemoglobinemia
- MRD 8.8mg/kg 600mg
- pKa 7.9
- pH 6.0-7.0
- Half life is 96 minutes
- FDA pregnancy category B
What is methamoglobinemia?
- A condition in which a form of hemoglobin called methemoglobin builds up in the blood and oxygen is unable to be carried effectively to body tissues which results in cyanosis.
- In severe cases can be life threatening
- Symptoms include: pale, gray/blue skin, lips and nail beds, shortness of breath, fatigue, confusion, headache, lightheadedness and increase heart rate
What are the properties of articaine?
- 1/3 more potent than lidocaine
- Intermediate duration 60-75 min of pulpal anesthesia, 3-6 hours of soft tissue anesthesia
- Classified as an amide, but different aromatic ring structure with an ester component attached..this promotes more rapid biotransformation, more lipophilic
- Metabolized by plasma esterase and by the liver advantage is that it decreases the half life therefore decreasing the risk of toxicity.
- Better diffusion properties than lidocaine
- MRD 7 mg/kg 500mg
- Some controversial increase in risk of parathesia with the IANB “not due to any proven increased incidence of parathesia but due to the opinion that articaine may cause paresthesia more frequently than other drugs”
- 4% 1:200,000 and 1:100,000 clinically equivalent
- Risk of methemoglobinemia when used in higher than therapeutic devices
- 2% excreted unchanged
- Vasodilation equal to lidocaine, greater than mepivicaine
- pKa is 7.8,,but since articaine is slightly more lipophilic a slightly faster onset is reported
- ph 4.6-5.4 half life, 44.4 min
- Onset on infiltration is 1-2 min (most rapid), 2-3 min with a nerve block
What are the properties of bupivacaine?
- Most potent and toxic
- 4X more potent than lidocaine
- Increased duration long acting used with post operative pain control needed
- 1.5-3 hours of pulpal anesthesia,4-9 hours of soft tissue anesthesia
- Metabolized in the liver slowly, half life 2.7-3.5 hrs
- Highest pKa – slower onset
- MRD 1.3mg/kg 90mg
What are the therapeutic actions of topical anesthetics?
block nerve conductions at the surface of the skin….decreased permeability of sidum, decreased polarization
What are the uses of topical anesthetics in dentistry?
- tx of minor injuries (sprays, gels)
- reduce gag reflex (sprays)
- teeth, apthous ulcers, dentures
- rubber dam clamp placement
- prior to injection
- calculus removal??
What are the ideal properties of a topical anesthetic
- nonallergenic
- produce no local damage to tissue
- allow pain-free application
- have an acceptable taste
- remain at the site of application
- produce reliable anesthesia
- produce sufficient duration of anestheisa
- produce no systemic toxicity
What are some delivery systems of topical?
- gels, creams
- liquids
- sprays
- patches
- injectables
List any potential toxicity and adverse effects
- concentration higher to facilitate diffusion, therefore increased risk of toxicity
- irritation, sloughing, alteration o ftaste, discoloration at the site of injection
- CNS and CVS effects: excitatory effects followed by depression, rare
- esters increased risk of allergic reaction
- do not apply to bleeding tissue
- unlike injectable anesthetics, MRD information is limited and the amount of topical provided to the client challenging to determine
What are the properties of benzocaine topical?
-most common, many flavours, MRD (not published)
-Ester, rapid onset 30s, poorly absorbed into the bloodstream so low risk of toxicity
-20% (range 6-20%) peak effect 2 min duration 5-10
Metabolized in the plasma to PABA (allergen)
-Caution with sprays. FDA category C(excretion in breast milk unknown)
-Note: benzocaine has been use in conc of 7.5%-10%..due to the risk of methemoglominemia. FDA recommends that these preparations should not be used on children under 2 years..parents should be aware of the signs and symptoms to watch for
What is the benzocaine spray warning?
avoid use with priocaine
What are the properties of lidocaine (xylocaine) topical?
- Gaining favour 2-5% concentrations
- Amide, 1-2 min onset peak 5-10 min
- MRD 200mg. FDA category B(enters breast milk)
What are the properties of tetracaine (surpacaine) topical?
Most potent .25%, ester, slow onset
What are the properties of oraqix
- 2.5% lidocaine, 2.5% prilocaine
- amide
- MRD (5cartridges)
- Eutectic mixture of lidocaine/prilocaine amide anesthetics
- Onset: 30 seconds
- Duration: 20 minutes
- MRD 5 cartridges
What are the properties of cetacaine topical
- Mixture of 14% benzocaine, 2% tetracaine, 2% butambem
- Spray, liquid and gel
- Increased speed of onset compared to individual agents
- Other advantage is depth to anesthesia which can be enough for some procedures
What are the side effects of topical anesthetics?
- Burning at site of injection
- Sloughing
- Tissue discolouration
- Alteration of taste
- CNS: excitatory: dizziness, tinnitus, disorientation..then depressant: slurred speech, drowiness, respiratiory impairment
- Some allergic reactions are delayed
What is the technique to applying topical?
- dry area first
- apply small amount of gel
- leave in place for 1-2 mins
- anesthesia should be achieved 2-3 mm into the tissue
What is the technique to applying topical?
- dry area first
- apply small amount of gel
- leave in place for 1-2 mins
- anesthesia should be achieved 2-3 mm into the tissue
What are the properties of vasoconstrictors?
- Epinephrine** and levonordefrin)
- ↓ blood flow
- ↑ duration by localizing the solution
- Will slightly ↓ rate of onset…why?
- Slow absorption into CVS
- ↓ probability of toxicity
- during debridement, soft tissue manipulation can lead to bleeding, vasoconstrictors can counteract unwanted bleeding
What are vasoconstrictors?
: structurally identical to natural, non steroid mediators of sympathetic nervous system epinephrine and norepinephrine secreted by the adrenal medulla of the brain
Define sympathetic
fight or flight component of autonomic nervous system
Define derenergic sympathomimetic
mimic similar effects as those caused by stimulation of adrenergic nerves
Define catacholamines
naturally occurring
such as epinephrine
What are catacholamine
sympathetic receptors
B1, B2, A1, A2
What are the sympathetic responses indicative to fight or flight response?
-heart - increase rate and force of contraction
-blood pressure increases
-dilated airway
-respirations increased
increase metabolism and glucose levels
What is the mode of action of epinepherine?
- Slowing of the vascular uptake allows more time for drugs to enter nerve membranes and block receptor sites
- Increases duration
- Also some direct action of epinephrine that may contribute to the profoundness of the anesthesia
What are the therapeutic effects of vasoconstrictors?
α receptors: vasoconstriction, excitatory action of α receptors on smooth muscle in blood vessels
Α effects occur first, Β2 dilation occurs later
What are the non-therapeuitc inhibitory effects of vasoconstrictors?
Β1 receptors**:cardiac stimulation
increases heart rate, stroke volume,
and cardiac output and the small
intestines (causing lipolysis)
Β2 receptors: bronchi, bronchodilation, vascular beds and the uterus
α effects occur first, Β2 dilation occurs later
What are the uses of vasoconstrictors in anaphylaxis?
- Anaphylaxis presents as peripheral vasodilation and bronchial constriction
- α adrenergic stimulation provides peripheral vasoconstriction and B provides bronchodilation
What is the debate surrounding vasoconstrictors?
- Use of vasoconstrictor or not?
- Must balance the potential benefit of increased duration verses risk of production of endogenous epinephrine
- Endogenous epinephrine release can be greater than the amount given
- What could happen if the client was anxious prior to injection?
- Potential allergy-synthetic epi not stable therefore sodium bisulfite is added to prevent oxidation. This increases allergy potential and decreases pH (3.3-5.5) ↓dissociation
What is the concentration of vasoconstrictors?
-Referred to as a ratio rather than % listed with the concentration or solution
4% Articaine 1:200,000 epinephrine
-1:100,000
1 g dissolved in 100,000ml or .01/mg/ml)
-1:50,000 – used for hemostasis
What must the DH consider when selecting an anesthetic agent?
- Length of procedure
- Medical status of the client(significant CVD, hyperthyroidism, sulfite allergies, some meds)
- Need for hemostasis…important to weigh the benefit of 1:50,000 with risk
- Vasoconstrictor rebound: as the tissue level of the vasoconstrictor begins to decline, Β2 actions begins to predominate which can potentially increase bleeding ( post op bleeding approx 6 hours after procedure)
What is vasoconstrictor rebound?
as the tissue level of the vasoconstrictor begins to decline, Β2 actions begins to predominate which can potentially increase bleeding ( post op bleeding approx 6 hours after procedure)
What is the termination of action of vasoconstrictors?
- Absorption of epinephrine is retarded by vasoconstrictive properties
- Once absorbed epinephrine is inactivated by enzymes catechol-O-methyltransferase(COMT) and monoamine oxidase (MAO) in the blood
- 1% of epinephrine is excreted by the kidney
What are some precautions when using vasoconstrictors?
- Hypertension
- Cardiovascular disease (unstable angina, arrhythmias )
- Hyperthyroidism
- Demonstrated hyper responder
- Phenothiazides reduce max dose to .04 mg/appt
Note: with accidental deposition directly intravascularly..body very efficient at removing 5-10 min
What are contraindications to using vasoconstrictors?
- Significant cardiovascular disease ( ASA III or IV)
- Sulfite allergies
- Tricyclic antidepressants (↑BP worse if patient has potential for arrhythmias
- Non specific B blockers (↑BP and reflex bradycardia) now have selective B blockers
- suspected use of cocaine or
methamphetamine
-MI within last 6 months
-Coronary bypass within last 6 months
-Uncontrolled high BP (200/115)
-Uncontrolled angina (daily episodes)
-Uncontrolled arrhythmias
-Sulphite allergies **
-Adrenal gland tumours
-Uncontrolled hyperthyroidism (thryoid storm)
-Cocaine/ methamphetamine
-Glaucoma
What is the significance of cardiovascular disease when using vasoconstrictors?
-ASA III patients are treatable with appropriate modifications
What is the significance of patients taking tricyclic antidpressants when using vasoconstrictors?
increases effects of vasoconstrictor; both epinephrine and levonordefrin may cause acute hypertension and cardiac dysrhythmia but levonordefrin to a greater degree
What is the significance of patients taking nonselective beta blockers when using vasoconstrictors?
increased hypertension resulting in rebound bradycardia, potential cardiac arrest
What is the significance of patients with diabetes when using vasoconstrictors?
vasoconstrictors directly oppose effect of insulin, possible chagnes in blood levels of glucose; amounts used in dentistry are generally safe and do not significantly raise blood sugar levels
What is the significance of patients with controlled hyperthyroidism when using vasoconstrictors?
sensitivity to vasoconstrictors increasing their effect
What is the significance of patients taking phenothiazines when using vasoconstrictors?
haloperidol: chlorpromaxine (Thorazine) may reverse the pressor effect of vasoconstrictors resulting in an increased risk of hyptension, and have been noted to antagonize the peripheral vasoconstrictive effects of epinephrine
What is the significance of patients taking digitalis glycosides when using vasoconstrictors?
epinephrine increases the potential for cardiac arrhythmias
What is the significance of patients taking levodopa, thyroid hormones when using vasoconstrictors?
large doses of epinephrine may cause cardiac toxicity
What is the significance of patients taking COMT inhibitors when using vasoconstrictors?
may enhance systemic actions of vasoconstrictors
What is the significance of patients taking CNS stimulants when using vasoconstrictors?
effects of stimulant or vasoconstrictor may occur
What is the maxiumum dose of epinephrine for a healthy adult?
0.2 mg/appt (0.1 mg Levonordefrin)
what is the maximum dose of epinephrine for a cardiac patient?
0.04 mg/appt (0.2 mg Levonordefrin)
What is the formula for determining maximum dosage of epinephrine?
volume X concentration X 1,000 = mg of epi
eg: 1.8ml x 1/100,000 x 1000 = 0.018 mg
How do you determine the maximum dose in carpules of epinephrine in a healthy person assuming that the LA is not the limiting factor
MRD/#mg of epi
- 2/0.018 = 11 carpules
(0. 018 came from volume x concentration x 1000…. - 8 x 1/100,000 x 1000)
What are the specific vasoconstrictors?
epinephrine (adrenalin) norepinephrine levonordefrin phylephrine (neo-synephrine) felypressin
What are the properties of epinephrine?
most common, 1:50,000, 1:100,000, 1:200,000 receptor sites (alpha and beta1 and 2)
What are the properties of norepinephrine?
naturally occuring catecholamine..activates alpha receptors causing extreme peripheral constriction which can ↑BP use not recommended in dentistry
What are the properties of levonordefrin?
(Neo-Cobefrin)-synthetic vasoconstrictor 15% as potent as epinephrine, requires sulphites to stabilize , selective alpha receptor agonist with less beta activity. Inactivated by COMT and not MAO
What are the properites of Phenylephrine?
(Neo-Synephrine) alpha agonist, less potent than epinephrine (not used in dentistry)
What are the properties of felypressin?
used in Great Britain little to no effect on myocardium and is not metabolized by MAO
