What symptoms might indicate a more severe local anesthetic overdose?
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Drowsiness and disorientation.
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What symptoms might indicate a more severe local anesthetic overdose?
Drowsiness and disorientation.
What is pharmacokinetics?
The study of the action of drugs within the body.
How are local anesthetics absorbed when administered orally?
With the exception of cocaine, local anesthetics are poorly absorbed from the gastrointestinal tract.
What is the elimination half-life of local anesthetics?
The rate at which local anesthetics are removed from the blood, or the time necessary for a 50% reduction in the blood level.
In what form does procaine primarily appear in the urine?
Procaine appears in the urine primarily as PABA (90%) with 2% unchanged.
What does the toxicity of a local anesthetic depend on?
A balance between absorption and metabolism.
Which method of injection produces the most rapid elevation of blood levels of local anesthetics?
Intravenous (IV) injection.
What is a primary metabolite of prilocaine and what condition can it cause?
Orthotoluidine, which can cause methemoglobinemia.
What does procaine (an ester local anesthetic) undergo hydrolysis to?
p-aminobenzoic acid (PABA).
What is metabolism in the context of local anesthetics?
The means by which the body transforms the active drug into an inactive form.
Where is the primary site of biotransformation for amide local anesthetics?
The liver.
Into what two major groups are local anesthetics divided?
Esters and amides.
What are the consequences of peripheral vasodilation caused by local anesthetics?
Peripheral vasodilation leads to blood vessel relaxation, increased blood flow, increased drug absorption, decreased depth and duration of local anesthetic action, increased bleeding, and increased local anesthetic blood levels.
What are the four main actions included in pharmacokinetics?
Absorption, Distribution, Metabolism, Excretion.
What factors influence the rate of absorption of local anesthetics after injection?
The site vascularity and the vasoactivity of the drug.
Which local anesthetic produces cutaneous vasoconstriction?
Ropivacaine produces cutaneous vasoconstriction.
What is the pharmacologic action of local anesthetics on the CNS?
The pharmacologic action of local anesthetics on the CNS is depression.
How does the blood level of local anesthetics affect their clinical action?
The higher the blood level, the greater the clinical action.
Where does prilocaine primarily undergo metabolism?
In the liver, with some occurring in the lung.
Do the metabolites of lidocaine produce sedation?
Yes, unlike lidocaine itself, its metabolites can produce sedation.
What is the general effect of most local anesthetics on peripheral blood vessels?
Most local anesthetics produce peripheral vasodilation.
What auditory disturbances might occur during a local anesthetic overdose?
Tinnitus (ringing in the ears).
What are the CNS effects of local anesthetics at low (therapeutic, nontoxic) blood levels?
At low (therapeutic, nontoxic) blood levels, there are no significant CNS effects.
What is the effect of a normal dose of local anesthetics on the respiratory system?
It has a direct relaxant action on bronchial smooth muscle.
Which amide local anesthetics primarily undergo liver metabolism?
Lidocaine, mepivacaine, etidocaine, and bupivacaine.
How are ester local anesthetics metabolized?
They are hydrolyzed in the plasma by the enzyme pseudocholinesterase.
What effect does bupivacaine have on blood vessels?
Bupivacaine produces vasodilation.
What unusual taste might be experienced during a local anesthetic overdose?
Metallic taste.
Which organs initially have higher anesthetic blood levels due to high perfusion?
Brain, head, liver, kidneys, lungs, and spleen.
Is a proportion of local anesthetics excreted unchanged in the urine?
Yes, a proportion of local anesthetics is excreted unchanged in the urine.
Which system is more resistant to the effects of local anesthetic drugs, the cardiovascular system or the central nervous system?
The cardiovascular system is more resistant than the central nervous system to the effects of local anesthetic drugs.
What is the cause of allergic reactions that rarely occur in response to ester local anesthetics?
They are related to p-aminobenzoic acid (PABA).
What can increasing local anesthetic blood (plasma) concentration lead to?
Increasing local anesthetic blood (plasma) concentration can lead to overdose (toxic reaction).
What is a critical symptom indicating a severe local anesthetic overdose?
Loss of consciousness.
Do local anesthetics cross the blood-brain barrier?
Yes, local anesthetics cross the blood-brain barrier.
What are some signs of minimal to moderate overdose levels of local anesthetics?
Talkativeness, apprehension, excitability, slurred speech, muscle twitching (face and extremities), euphoria, sweating, vomiting, elevated blood pressure, elevated heart rate, and elevated respiratory rate.
How are local anesthetics absorbed when applied topically?
Local anesthetics are absorbed at differing rates after application to mucous membranes.
What percentage of a cocaine dose is found unchanged in the urine?
10% of a cocaine dose is found unchanged in the urine.
What are the initial symptoms of local anesthetic overdose?
Lightheadedness and dizziness.
Which local anesthetic produces vasoconstriction?
Cocaine produces vasoconstriction.
What are most of the systemic actions of local anesthetics related to?
Their blood or plasma level in a target organ (CNS, CVS).
Which local anesthetics can produce surface anesthesia of intact skin?
Lidocaine and prilocaine (EMLA).
How is methemoglobinemia managed?
With methylene blue.
What effect do most local anesthetics (LA) have on blood vessels after injection?
Most local anesthetics produce dilation of the blood vessels after injection.
How can you distinguish amide local anesthetics from ester local anesthetics based on their names?
Amides contain a double 'i' in their names.
What can an overdose of local anesthetics cause in the respiratory system?
It can produce respiratory arrest as a result of generalized CNS depression.
For what medical condition is intravenous injection of local anesthetics used?
Management of ventricular dysrhythmias.
What represents a relative contraindication to ester local anesthetics?
Atypical pseudocholinesterase.
What symptoms might follow lightheadedness and dizziness in a local anesthetic overdose?
Restlessness and nervousness.
What visual disturbances might occur during a local anesthetic overdose?
Inability to focus.
What are some signs of moderate to high overdose levels of local anesthetics?
Tonic-clonic seizure activity followed by generalized CNS depression, depressed blood pressure, heart rate, and respiratory rate.
What is the primary excretory organ for local anesthetics and their metabolites?
The kidneys.
Why do patients with renal impairment have an increased potential for toxicity from local anesthetics?
Because their ability to excrete local anesthetics and their metabolites is reduced.
What are some examples of esters of benzoic acid used as local anesthetics?
Butacaine, Cocaine, Benzocaine, Hexylcaine, Piperocaine, Tetracaine.
How does vasodilation affect the absorption of local anesthetics?
Vasodilation increases local anesthetic absorption into the blood, thus decreasing the duration and quality of pain control.
Why does skeletal muscle contain the greatest percentage of local anesthetics?
Because it is the largest mass of tissue, despite not being highly perfused.
How is articaine metabolized?
Articaine is metabolized in the blood (primarily) and the liver due to its ester and amide components.
Which ester local anesthetic is the most rapidly hydrolyzed and least toxic?
Chloroprocaine.
What are some examples of esters of p-aminobenzoic acid used as local anesthetics?
Chloroprocaine, Procaine, Propoxycaine.
What factors can impair the biotransformation of amide local anesthetics?
Lower hepatic blood flow (hypotension, congestive heart failure) or poor liver function (cirrhosis).
Which ester local anesthetic is hydrolyzed 16 times more slowly than chloroprocaine and has the greatest toxicity?
Tetracaine.
What sensation might occur before actual twitching is observed in a local anesthetic overdose?
Sensation of twitching.
What effect does IV administration of local anesthetics have on pain threshold and analgesia?
IV administration of local anesthetics increases the pain threshold and produces analgesia.
What effect does cocaine have on blood vessels at commonly used dosages?
Cocaine produces vasoconstriction at commonly used dosages.
Which local anesthetic is the most potent vasodilator?
Procaine is the most potent vasodilator.
What can happen at higher (overdose, toxic) levels of local anesthetics?
At higher (overdose, toxic) levels, local anesthetics can cause generalized tonic-clonic convulsions.
What are some examples of amide local anesthetics?
Articaine, Bupivacaine, Dibucaine, Etidocaine, Lidocaine, Mepivacaine, Prilocaine, Ropivacaine.
