PHYSICAL EVALUATION & PHARMACOLOGY OF LOCAL ANESTHESIA & PHARMACOLOGY OF VASOCONSTRICTORS
Order by
67 terms
Terms | Definitions |
|---|---|
 Drug-drug interactionsCimetadine and Lidocaine: | increases 1/2 life, overdose potential |
| Drug-drug interactions Sulfonamides and Esters: | inhibits antibacterial action |
| Drug-drug interactions Non-selective beta-blockers and epinephrine: | elevated BP and bradycardia Tricyclic antidepressants and epinephrine/norepinephrine/levonordefrin hypertensive crisis |
| Drug-drug interactions Monoamine Oxidase Inhibitors and Epinephrine: | hypertensive crisis |
| Drug-drug interactions Phenothiazines & Epinephrine: | postural hypotension |
| Drug-drug interactions Cocaine & Epinephrine/LAs: | hypertension, cardiac arrest, overdose of local anesthetic |
| Malignant Hyperthermia | Most intense life-threatening complication associated with general anesthesia 1/15,000 children 1/50,000 adults Genetically transmitted syndrome Relative contraindication to AMIDE local anesthetics Rise in Calcium concentration in myoplasm Tachycardia, fever, cardiac dysrhythmias, muscle rigidity, cyanosis, and death after exposure to triggering agent 10% mortality rate Not likely with dental anesthesia (consult M.D., use caution) Normal doses or amides and esters may be used Nitrous oxide/oxygen has induced a case of Malignant Hyperthermia do not use if history of Malignant Hyperthermia! Management--discontinue inhalation anesthetics and give 100% oxygen, 911, administer sodium bicarbonate, "cool" |
| Atypical Plasma Cholinesterase | 1 out of 2,820 inherit this trait Apnea and overdose of esters possible because esters hydrolyzed in blood by plasma cholinesterase Amides OK (liver metabolism) |
| Methemoglobinemia--Inborn or Acquired | Cyanosis with out cardiac/respiratory abnormalities;oxygen won't help Articaine, Prilocaine, and topical Benzocaine can induce it Elevation of methemoglobin due to iron in ferric state in blood 3 to 4 hours after Treatment, cyanosis, brown blood, respiratory distress |
| Local Anesthetics v.s. Other Drugs | Local anesthetics have clinical effect when absorbed from site of administration Others need to get into cardiovascular system in order to work |
| Classification of Local Anesthetics ESTERS: | •Butacaine •Cocaine •Benzocaine •Hexylcaine •Piperocaine •Tetracaine •Chloroprocaine •Procaine •Propoxycaine |
| Classification of Local Anesthetics AMIDES: | •Articaine •Bupivicaine •Dibucaine •Etidicaine •Lidocaine •Mepivicaine •Prilocaine |
| Classification of Local Anesthetics QUINOLINE: | •Centbucridine |
| Pharmacokinetics of Local Anesthetics Uptake: | •Vasodilating activity •**Procaine (ester)—most •Cocaine (ester)—exception •More is absorbed AWAY from site •Shorter duration •More chance of overdose |
| Route of Administration affects Peak Time in Blood: Oral | only cocaine absorbed orally |
| Route of Administration affects Peak Time in Blood: Topical | not absorbed through intact skin; tracheal mucosa, fast; pharyngeal, slower |
| Route of Administration affects Peak Time in Blood: Injection | I V most rapid; subcutaneous and I M depends on vascularity and vasoactivity of drug |
| Distribution of Drug to all tissues | •Highly perfused have more initially •Skeletal more due to mass •Drug level in certain organs related to toxicity •Blood level influenced by rate of absorption, distribution, and elimination •Healthy people faster; esters faster elimination |
| Metabolism (Biotransformation) ESTERS: | •Hydrolyzed in plasma by enzyme pseudocholinesterase •Rapid hydrolysis means less toxic •Paraaminobenzoic acid (major metabolic product) + diethylamino alcohol (excreted in urine •Most allergies related to PABA •1/2800 has atypical pseudocholinesterase •Cannot hydrolyze esters or like drugs •Hereditary, note Medical History for problem with general anesthetic/succinylcholine •Absolute contraindication: toxic, lethal •Relative contraindication: risk/benefit/dose |
| Metabolism (Biotransformation) Amides: | •More complex metabolism •Metabolized in liver, most at same rate •70% biotransformed in healthy individuals •Relative contraindication for those with poor liver function, congestive heart failure due to increased blood level, toxicity •Metabolites of amides can cause sedation, methemoglobinemia if accumulated |
| Excretion | •Kidneys—urine •Esters—small percent of parent compound •Amides—high percent of parent compound •Relative contraindication to local anesthetic significant renal impairment due to toxicity |
| Systemic Actions of Local Anesthetics | •CNS and CVS most affected •(Quinoline Centbucridine—little effect, long lasting, potent--NEW) •Effect depends on blood level •Crosses blood-brain barrier •Pharmacological effect is depression |
| Local Anesthetics CNS Effects | •At lower levels—lidocaine, procaine, mepivicaine ANTI-convulsants to TREAT seizures •1st signs of overdose/toxicity in CNS •At TOXIC level—tonic/clonic seizure •Anti-convulsive .5-4 microgram/ml •Pre-seizure 4.5-7 microgram/ml •Tonic/clonic more than 7.5 microgram/ml |
| Local Anesthetics Pre-Convulsive State Objective observed | •Slurred speech •Shivering •Muscle twitching •Tremor in face and distal extremities |
| Local Anesthetics Pre-Convulsive State Subjective felt | •Numbess—tongue, circumoral •Warm, flushed skin •Dreamlike state •Lightheadedness •Dizziness, drowsiness •Visual and auditory disturbance •Disorientation |
| Local Anesthetics Toxicity | •Lidocaine and procaine, mild sedative or drowsiness effect •If noted in first 10 minutes after anesthetic administration WATCH for convulsion or other serious effect |
| Local Anesthetics Convulsive Phase | •Duration of seizure related to blood level of local anesthetic and inversely to arterial PCO2 •Higher CO2, less anesthesia necessary to cause toxicity or seizures of longer duration •Most seizures self-limiting as blood flows and level reduces •If level of local anesthesia in blood increases: seizures stop, generalized CNS depression, and respiratory depression |
| Why Stimulation before Depression of CNS? | •Selective depression of inhibitory impulses before facilitory impulses •Excitable impulses still get through first •Eventually both get depressed and respiratory depression occurs |
| Other CNS Effects Analgesia | I V for chronic pain in 1940-50 Narrow safety margin, not used today |
| Other CNS Effects Mood Elevation | Cocaine Wm. Halsted, father of American Surgery, 1st to administer local anesthetic: ADDICT! |
| Cardiovascular System | •not as affected as CNS •Direct action on myocardium and peripheral vasculature •Procaine and lidocaine used to TREAT cardiac arrhythmias |
| Myocardium | •Depression related to blood level of LA •no cardio depressant activity by 1 -2 cartridges of Lidocaine •Overdose signs and symptoms •more than 6 micrograms/ml |
| Peripheral Vasculature | •Vasodilation (except cocaine) •Increased blood flow •rate of absorption •blood levels/toxicity •bleeding time in Treatment area •Decreased duration of anesthesia •Primary effect on BP is HYPOTENSION |
| Sequence of LA Induced Actions on the CVS Normal level | slight increase in BP, peripheral vasoconstriction |
| Sequence of LA Induced Actions on the CVS Just below overdose | mild hypotension |
| Sequence of LA Induced Actions on the CVS Overdose | profound hypotension |
| Sequence of LA Induced Actions on the CVS Lethal | cardiovascular collapse, massive vasodilation, decreased contractility and heart rate |
| Local tissue toxicity | reversible skeletal muscle irritation, no overt clinical signs |
| Respiratory | normal: relaxant overdose leads to respiratory arrest |
| Clinical Manifestations of Local Anesthetic Overdose | •Confusion •Talkativeness •Apprehension •Excitedness •Slurred speech •Stutter •Muscle twitching •Nystagmus •Elevated heart rate, BP, respiration •Headache •Lightheadedness •Dizziness •Blurred vision •Ringing in ears •Numb tongue, perioral •Flushed or chilled •Drowsiness •Disorientation •Loss of consciousness •Seizure—CNS depression, Low BP, pulse, respiration |
| VASOCONSTRICTORS as additions to local anesthetics | •Drugs that constrict blood vessels and control tissue perfusion •1. Decreases blood flow to site •2. Slows absorption into CVS •3. Decreases risk of toxicity •4. Increases duration of anesthesia •5. Decreases bleeding at site |
| Chemical Structure | •Like epinephrine or norepinephrine: natural •Isoproterenol & levonordefrin: synthetic •Sympathomimetic or adrenergic drugs •Classification related to presence or absence of catecholnucleus •With amine group, they are catecholamines |
| Modes of Action Direct acting | on adrenergic receptors are epinephrine, norepinephrine, and levonordefrin |
| Modes of Action Indirect acting | by releasing •norepinephrine from adrenergic nerve terminal: amphetamines,methamphetamines |
| Modes of Action Mixed acting | both direct and indirect: •ephedrine |
| Adrenergic Receptors | •Alpha and beta •Activation of alpha receptors causes contraction of smooth muscle in blood vessels •Activation of beta receptors causes relaxation of smooth muscle, vaso and bronchodilation, and cardiac stimulation |
| Release of Catecholamines | •Some drugs act INDIRECTLY •Causes release of catecholamine and norepinephrine from stores in adrenergic nerve terminals •Actions similar to norepinephrine •Repeated doses is less effective tachyphylaxis is not seen with drugs that act DIRECTLY on adrenergic receptors |
| Dilutions of Vasoconstrictors | •Ratio--mg of drug/ml of solution •1:100,000 dilution = 0.01 mg/ml •Common dilutions used in dentistry •1:100,000* 1:50,000 1:200,000 •Adrenaline discovered in 1897 •Braun--1903 add to LA to prolong duration •(1:100,000 epinephrine most commonly used by RDH**) |
| Epinephrine Most Commonly Used | •Weigh risks and benefits especially if CV or thyroid disease •Absorbed at site of injection •Epinephrine blood levels influence heart and blood vessels is dose dependent •Resting plasma epinephrine levels doubled following 1 cartridge of LA with 1:100,000 epinephrine for several to 30 minutes |
| Epinephrine Reaction | •Apprehension, tachycardia, sweating, pounding in chest (palpitations) •Can happen EVEN if SAFE technique used •Due to: absorption of drug, drug interaction, •I V administration, hyper-responders •Increases heart rate 25 -70 beats/minute •Raises BP 20 -70 mg Hg •May cause rhythm disturbances •(often happens with intravascular injection prevent by frequent aspiration!) |
| Epinephrine (Adrenaline) | •Acid salt highly soluble in water •Oxidation hastened by heat and heavy metal ions •Sodium bisulfite prolongs shelf life •Vasoconstrictor in LA is what shortens shelf life of cartridges •Available from animals or synthetic form •Acts on alpha and beta*adrenergic receptors |
| Systemic Actions Cardiovascular System | •Increased systolic and diastolic pressures •Increased cardiac output •Increased stroke volume and heart rate •Increased strength of contraction •Increased oxygen consumption •Dilation of coronary arteries •OVERALL DECREASED EFFICIENCY |
| Beta receptors affected first (dilation) so: | •Initially, diastolic BP DECREASES •systolic and heart rate increase •Then with higher doses, diastolic BP INCREASES |
| Epinephrine: Other Systemic Effects Respiratory system | bronchodilator for acute asthma |
| Epinephrine: Other Systemic Effects CNS | not a potent stimulator at normal dose, only at excessive dose |
| Epinephrine: Other Systemic Effects Metabolism | increases oxygen consumption and blood glucose (4 cartridges 1:100,000) |
| Epinephrine:Termination of Action and Elimination | •Terminated primarily by re-uptake by adrenergic nerves •Rest is inactivated by liver enzymes •1% excreted unchanged in urine •Stimulatory phase brief due to rapid inactivation of epinephrine |
| Epinephrine:Side Effects and Overdose | •CNS stimulation •fear, anxiety, tension, restlessness, •tremor, headache, weakness, dizziness, •pallor, respiratory difficulty, palpitations •CV dysrhythmmias with increased blood level •BP elevation--systolic more than 300/diastolic more than 200 •Stroke, angina |
| Clinical Applications of Epinephrine | •Management of acute allergic reactions •Management of bronchospasm •Treatment of cardiac arrest •To produce mydriasis •*Vasoconstrictor for hemostasis and for decrease of absorptioninto CVS from LA •*Vasoconstrictor to increase duration of LA |
| Epinephrine: Maximum Doses | •For pain control, use least concentrated solution that produces effective pain control •CV disease--risk/benefit, limit or avoid •4 ml of 1:100,000 dilution or 2 cartridges (cardiac dose**) •Normal--.2 mg per appointment •20 ml of 1:100,000 dilution or 11 cartridges •(1:50,000--5 cartridges, 1:200,000--22 cartridges)--limited by max. volume of LA |
| Hemostasis | •Higher concentration = more hemostasis •Use 1:100,000 for dental procedures •Effective and better than no vasoconstrictor •Clinically for surgery--initial hemostasis, •LATER vasodilation and post-surgical bleeding (6 hours) |
| Other Vasoconstrictors Norepinephrine | 1/4 as potent as epinephrine, works on alpha receptors, causes decreased heart rate, not effective for bronchospasm, soft tissue necrosis on palate •not RECOMMENDED FOR DENTAL ANESTHESIA |
| Other Vasoconstrictors Levonordefrin (Neo-Cobefrin) | 15% as potent as epinephrine, less CV and CNS effect • is USED IN DENTISTRY with Mepivicaine or Propoxycaine/Procaine •1:20,000 dilution •Maximum dose 1 mg per appointment •20 ml of 1:20,000 solution or 11 cartridges |
| Other Vasoconstrictors Phenylephrine Hydrochloride (Neo-Synephrine) | not used in dentistry |
| Other Vasoconstrictors Fenylpressin (Octapressin) | wide safety margin, not recommended for hemostasis, not AVAILABLE IN U.S. |
| SELECTION OF VASOCONSTRICTOR | •Length of procedure--typically need 50 minutes of pulpal anesthesia •Need vasoconstrictor for long anesthesia: •Lidocaine without vasoconstrictor •5-10 minutes duration of anesthesia •Lidocaine with vasoconstrictor** •60 minutes duration of anesthesia •(usually best for scaling and root planing**) •Requirement for hemostasis-- •Epinephrine with alpha receptor effects is good, but rebound occurs--not usually a problem in dentistry •Small volume of anesthetic needed to achieve hemostasis deposited locally into area of bleeding •(hemostasis is benefit during scaling and root planing**) |
| Medical status of patient | CONSULT M.D. •Few contraindications except: •significant CV disease, •thyroid dysfunction, diabetes, sulfite •sensitivity, patients on MAO inhibitors, •tricyclic anti-depressants, phenothiazine •Usually best to use vasoconstrictor |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.