Drug Biotechnology Questions and Answers – Mechanism of Action of Local Anesthetic

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This set of Drug Biotechnology Problems focuses on “Mechanism of Action of Local Anesthetic”.

1. What is the function of local anesthetics?
a) Suppress the activity of the brain
b) Render a specific portion insensitive to pain
c) Suppress the function of a whole organ
d) Make the patient’s full body insensitive to pain
View Answer

Answer: b
Explanation: Local anesthetics are also called regional anesthetics. Used to render a specific portion of the body insensitive to pain. They interfere with nerve impulse transmission to specific areas of the body. These anesthetics do not cause loss of consciousness.
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2. Which of the following is the parenteral application of local anesthetics?
a) When applied to the mucous membrane
b) When applied to the skin
c) When injected to CNS through spinal injection techniques
d) Using ophthalmic drops
View Answer

Answer: c
Explanation: Parenteral applications are injected to the CNS through various spinal injection techniques. Topical application is applied directly to the skin or mucous membranes. These can be done through creams, solutions, ointments, gels, ophthalmic drops, lozenges, suppositories, etc.

3. Which of the following are natural local anesthetics?
a) Cocaine
b) Benzocaine
c) Benzyl alcohol
d) Clove oil
View Answer

Answer: a
Explanation: Natural anesthetic is cocaine. Due to its uses in drug abuse, this is not used anymore in practices. Synthetic nitrogenous local anesthetics are procaine, benzocaine, lignocaine, cinchocaine, bucricaine. Synthetic non-nitrogenous will be benzyl alcohol and propanediol. Clove oil, phenol, chlorpromazine can also be used as a local anesthetic.
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4. Which of the following is synthetic nitrogenous local anesthetic?
a) Cocaine
b) Benzocaine
c) Benzyl alcohol
d) Clove oil
View Answer

Answer: b
Explanation: Natural anesthetic is cocaine. Synthetic nitrogenous local anesthetics are derivatives of PABA e.g. procaine, benzocaine, a derivative of acetanilide e.g. lignocaine, a derivative of quinoline e.g. cinchocaine, bucricaine. Synthetic non-nitrogenous will be benzyl alcohol and propanediol. Clove oil, phenol, chlorpromazine can also be used as a local anesthetic.

5. Which of the following is synthetic non-nitrogenous anesthetic?
a) Cocaine
b) Benzocaine
c) Benzyl alcohol
d) Clove oil
View Answer

Answer: c
Explanation: Natural anesthetic is cocaine. Synthetic nitrogenous local anesthetics are procaine, benzocaine, lignocaine, cinchocaine, bucricaine. Synthetic non-nitrogenous will be benzyl alcohol and propanediol. Clove oil, phenol, chlorpromazine can also be used as a local anesthetic.
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6. Apart from natural, synthetic, synthetic non-nitrogenous, which of the following is also a local anesthetic?
a) Cocaine
b) Benzocaine
c) Benzyl alcohol
d) Clove oil
View Answer

Answer: d
Explanation: Natural anesthetic is cocaine. Due to its uses in drug abuse, this is not used anymore in practices. Synthetic nitrogenous local anesthetics are procaine, benzocaine, lignocaine, cinchocaine, bucricaine. Synthetic non-nitrogenous will be benzyl alcohol and propanediol. Clove oil, phenol, chlorpromazine can also be used as a local anesthetic. Clove oil is being used in dentistry purposes.

7. Which of the following is the pharmacological action of local anesthetics?
a) Reversible block of conduction in nerve
b) Class II antidysrhythmic like action
c) Contraction of smooth muscle
d) Excitation of neuro-muscular transmission in skeletal muscle
View Answer

Answer: a
Explanation: Pharmacological action by local anesthetics are a reversible block of conduction in nerve, direct relaxation of smooth muscle & inhibition of neuromuscular transmission in skeletal muscle producing vasodilatation. Local anesthetics gives Class I antidysrhythmic like action on the heart.
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8. What does membrane expansion theory states?
a) The mechanism is not similar to the general anesthetics
b) Does not rely upon the lipophilic moiety of drugs
c) The molecules of the agent get incorporated into the lipid membrane
d) Causes nerve polarization
View Answer

Answer: c
Explanation: The membrane expansion theory depends upon the lipophilic moiety of local anesthetics agents. The molecules of the agent get incorporated into the lipid cell membrane which results in the swelling of the membrane. This provides physical obstruction of the sodium channels thus prevents nerve depolarization.

9. What does the specific receptor theory state?
a) Local anesthetics bind to various receptors
b) Produces chemical changes to the receptors
c) Tries to open all the closed sodium gates
d) Binding produces conformational changes
View Answer

Answer: d
Explanation: Local anesthetics bind to specific receptors within the sodium channel producing physical obstruction to the entry of sodium ions. The act of binding produces conformational changes within the channel. It binds to a closed gate and maintains it in the closed position.
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10. Which of the following factor do not affect the absorption of local anesthetics?
a) Vasodilating ability of drug
b) Volume and concentration
c) Vascularity of the tissue
d) Presence of vasodilator
View Answer

Answer: d
Explanation: Many factors influence the entry of local anesthetic into the circulation some of these are vasodilating ability of the drug, volume, and concentration of the drug, vascularity of the tissues, the route of administration of the drug, the presence of vasoconstrictor.

11. Which is the first local anesthetic?
a) Cocaine
b) Benzocaine
c) Benzyl alcohol
d) Clove oil
View Answer

Answer: a
Explanation: The first and most potent local anesthetic agent is cocaine though it is rarely used now used because of the problems of misuse. It is unique in it is the ability to produce intense vasoconstriction. The half-life of cocaine is 30 minutes. Dosage of cocaine when used as topical administration 4 – 10% solution of cocaine.

12. Which of the following is being used in dentistry when patients have an allergy from procaine?
a) Cocaine
b) Benzocaine
c) Benzyl alcohol
d) Procaine
View Answer

Answer: d
Explanation: Procaine is used in dentistry when the patients have proven allergy to the amide group. Used intra-arterially, to treat the arteriospasm which might occur during intravenous sedation. It has excellent vasodilatory properties. The first and most potent local anesthetic agent is cocaine used topically.

13. Which of the following is amide type drug?
a) Lignocaine
b) Cocaine
c) Procaine
d) Benzocaine
View Answer

Answer: a
Explanation: Benzocaine, procaine, and cocaine are ester type drugs. Procaine is used in dentistry when the patients have proven allergy to the amide group. Lignocaine is an amide-type drug. It is highly lipophilic and rapidly absorbed.

14. Which of the following is topical with high concentration?
a) Lignocaine
b) Cocaine
c) Procaine
d) Benzocaine
View Answer

Answer: d
Explanation: Used mainly as topical, due to its poor water solubility, and because of its low toxicity, it can be used in concentration up to 20%. Hydrolysed rapidly by plasma esterase to p-aminobenzoic acid accounting for its low toxicity. Lignocaine is an amide-type drug. It is highly lipophilic and rapidly absorbed.

15. Cocaine, when used for local anesthetics, has a half-life of 30 minutes.
a) True
b) False
View Answer

Answer: a
Explanation: The first and most potent local anesthetic agent, rarely used because of the problems of misuse. It is unique in it is the ability to produce intense vasoconstriction. Cocaine, when used topically for local anesthetic, has a half-life of 30 minutes.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter