12 Questions
What are some examples of soluble surface anesthetics?
Cocaine, Lignocaine
What are some examples of insoluble surface anesthetics?
Benzocaine, Oxethazaine
What are the differences between Ester LAs and Amide LAs?
Ester LAs have shorter duration, less intense analgesia, and higher hypersensitivity risk. Amide LAs have longer duration, more intense analgesia, and lower hypersensitivity risk.
What is the mechanism of action of local anesthetics?
Local anesthetics block action potential generation by blocking sodium channels. They interact with a receptor within the voltage sensitive Na channel and raise the threshold of channel opening.
What are the main unwanted effects of local anesthetics?
CNS effects (agitation, confusion, tremors, convulsions, respiratory depression), cardiovascular effects (myocardial depression, vasodilatation, fall in BP), allergic reactions, and hypersensitivity reactions.
What are some examples of Amides LA?
Lidocaine, Bupivacaine, Mepivacaine, Prilocaine
What are some characteristics of vasoconstrictors in local anesthesia?
Vasoconstrictors decrease the rate of vascular absorption, allowing more anesthetic to reach the nerve membrane, improving the depth of anesthesia, increasing duration of action, and decreasing systemic toxicity.
How does 1:200,000 epinephrine affect local anesthesia?
1:200,000 epinephrine is the best vasoconstrictor, which appears to improve the depth of anesthesia and increase the duration of action.
Explain the properties of ideal local anesthetics as mentioned in the text.
The properties of ideal local anesthetics include low systemic toxicity, quick onset of action, sufficient duration of action for the surgical procedure, solubility in water and stability in solution, and completely reversible effects.
What are the advantages of local anesthesia over general anesthesia?
Local anesthesia interrupts pain impulses in a specific region of the body without causing a loss of consciousness. It is normally completely reversible and does not have a residual effect on the nerve fiber. This is advantageous over general anesthesia.
List and briefly describe the two main types of local anesthesia mentioned in the text.
The two main types of local anesthesia mentioned are local infiltration and topical anesthesia. Local infiltration involves direct injection into tissues to reach nerve branches, while topical anesthesia is applied to the nose and mouth and is not as effective for skin.
Classify local anesthetics based on their chemical class, and provide examples for each class.
Local anesthetics can be classified into ester linked LA (-COO) and amide linked LA (-NHC-). Examples of ester linked LA include cocaine, procaine, tetracaine, and benzocaine, while examples of amide linked LA include lignocaine, bupivacaine, articaine, ropivacaine, mepivacaine, and etidocaine.
Study Notes
Surface Anesthetics
- Soluble surface anesthetics: Benzocaine, Tetracaine
- Insoluble surface anesthetics: Diphenhydramine
Local Anesthetics Classification
- Ester Local Anesthetics (LAs): Derived from benzoic acid or para-aminobenzoic acid, e.g., Tetracaine, Benzocaine
- Amide Local Anesthetics (LAs): Derived from amino acids, e.g., Lidocaine, Mepivacaine
Mechanism of Action
- Local anesthetics block nerve conduction by inhibiting sodium channels, preventing nerve impulses
Unwanted Effects
- Systemic toxicity, allergic reactions, and methemoglobinemia are possible unwanted effects of local anesthetics
Examples of Amide LAs
- Lidocaine, Mepivacaine, Bupivacaine, Ropivacaine, Prilocaine
Vasoconstrictors in Local Anesthesia
- Characteristics: Reduce bleeding, prolong anesthetic effect, and improve quality of anesthesia
- Examples: Epinephrine, Norepinephrine, Phenylephrine
Effect of Epinephrine on Local Anesthesia
- 1:200,000 epinephrine increases the duration of anesthesia and reduces bleeding
Ideal Local Anesthetics
- Properties: Fast onset, long duration, high potency, low toxicity, and minimal unwanted effects
Advantages of Local Anesthesia
- Less risk of respiratory and cardiac complications compared to general anesthesia
- Faster recovery and reduced risk of post-operative nausea and vomiting
Types of Local Anesthesia
- Central blockade: Spinal, epidural, and caudal anesthesia
- Peripheral blockade: Nerve blocks, field blocks, and infiltration anesthesia
Test your knowledge on local anesthetics with this quiz. Learn about the advantages, properties, classification, mechanism of action, rational uses, and differences between ester and amide local anesthetics. Understand the main unwanted effects and enhance your understanding of this important aspect of pharmacology.
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