MCQs PHARMACOLOGY: Peripheral nervous system

23.4 Depolarizing neuromuscular blockers differ from com-petitive blockers in the following attributes except: A. They induce contraction of isolated frog rec-tus abdominis muscle B. Ether anaesthesia intensifies block pro-duced by them C. Tetanic nerve stimulation during partial depolarizing block produces well sustained contraction D. Neostigmine does not reverse block produced by them

23.5 Succinylcholine produces spastic paralysis in: A. Rabbits B. Frogs C. Birds D. Patients with atypical pseudocholinesterase

23.6 The fall in blood pressure caused by d-tubocurarine is due to: A. Reduced venous return B. Ganglionic blockade C. Histamine release D. All of the above

23.7 Select the skeletal muscle relaxant that is commonly used for endotracheal intubation despite causing histamine release, K+ efflux from muscles and cardiovascular changes: A. Pipecuroniun B. Succinylcholine C. Pancuronium D. Cisatracurium
ANSWERS
2 3 . 4 B 2 3 . 5 C 2 3 . 6 D 2 3 . 7 B

23.8 Neuromuscular blocking drugs do not produce central actions because: A. They do not cross the blood-brain barrier B. Nicotinic receptors are not present in the brain C. They are sequestrated in the periphery by tight binding to the skeletal muscles D. They do not ionise at the brain pH

23.9 Pancuronium differs from tubocurarine in that: A. It is a depolarizing blocker B. Its action is not reversed by neostigmine C. It can cause rise in BP on rapid I.V. injection D. It causes marked histamine release

23.10 Which of the following drugs undergoes ‘Hofmann’ elimination: A. Succinylcholine B. Pancuronium C. Vecuronium D. Atracurium

23.11 The neuromuscular blocker that does not need reversal of action by neostigmine at the end of the operation is: A. d-Tubocurarine B. Doxacurium C. Pipecuronium D. Mivacurium

23.12 The most rapidly acting nondepolarizing neuromus-cular blocking agent which can be used as an alter-native to succinylcholine for tracheal intubation is: A. Rocuronium B. Pancuronium C. Doxacurium D. Pipecuronium
ANSWERS
2 3 . 8 A 2 3 . 9 C 23.10D 23.11D 23.12 A

23.13 Succinylcholine is the preferred muscle relaxant for tracheal intubation because: A. It produces rapid and complete paralysis of respiratory muscles with quick recovery B. It does not alter heart rate or blood pressure C. It does not cause histamine release D. It does not produce postoperative muscle soreness

23.14 Which of the following is applicable to mivacurium: A. It undergoes Hoffmann elimination B. It is the shortest acting nondepolarizing neuromuscular blocker C. It is excreted unchanged by kidney D. It does not cause histamine release

23.15 Neostigmine reverses the following actions of d-tubocurarine except: A. Motor weakness B. Ganglionic blockade C. Histamine release D. Respiratory paralysis

23.16 Postoperative muscle soreness may be a side effect of the following neuromuscular blocker: A. d-tubocurarine B. Succinylcholine C. Pancuronium D. Atracurium

23.17 The following antibiotic accentuates the nuromuscular blockade produced by pancuronium: A. Streptomycin B. Erythromycin C. Penicillin G D. Chloramphenicol
ANSWERS
23.13 A 23.14 B 23.15 C 23.16 B 23.17 A

23.18 Dantrolene sodium reduces skeletal muscle tone by: A. Reducing acetylcholine release from motor nerve endings B. Suppressing spinal polysynaptic reflexes C. Inhibiting the generation of muscle action potential D. Reducing Ca2+ release from sarcoplasmic reticulum in the muscle fibre

23.19 Which of the following is a centrally acting skeletal muscle relaxant: A. Carisoprodol B. Dantrolene sodium C. Quinine D. Decamethonium

23.20 Select the muscle relaxant that is used to control spasticity associated with upper motor neurone paralysis: A. Vecuronium B. Succinylcholine C. Chlorzoxazone D. Baclofen

23.21 The GABAB receptor: A. Is an intrinsic ion channel containing receptor B. Mediates neuronal depolarization C. Is insensitive to blockade by bicuculline D. Regulates intracellular cAMP

23.22 The following is a skeletal muscle relaxant that acts as a central α2 adrenergic agonist: A. Tizanidine B. Brimonidine C. Chlormezanone D. Quinine
ANSWERS
23.18D 23.19 A 23.20D 23.21 C 23.22A

23.23 Which of the following is not true of tizanidine: A. It is a clonidine congener used in spasticity due to stroke or spinal injury B. It reduces muscle tone by activating GABAB receptors C. It inhibits release of excitatory amino-acids in spinal interneurones D. It reduces muscle spasms without produ-cing weakness

23.24 Diazepam is used as a muscle relaxant for: A. Deep intra-abdominal operation B. Tracheal intubation C. Tetanus D. Diagnosis of myasthenia gravis

23.25 Indications of centrally acting muscle relaxants include all of the following except: A. Balanced anaesthesia B. Traumatic muscle spasms C. Torticollis D. Electroconvulsive therapy

24.1 The clinically used local anaesthetics have the follow-ing common features except: A. They are amphiphilic weak bases B. They are used for surgery in non-cooperative patients C. In their use, care of vital functions is gene-rally not needed D. They are safer than general anaesthetics in patients with respiratory and cardiovascular disease
ANSWERS
23.23 B 23.24 C 23.25 A 2 4 . 1 B

24.2 The local anaesthetics having amide linkage differ from those having ester linkage in that the amide-linked local anaesthetics: A. Are not surface anaesthetics B. Have a shorter duration of action C. Are degraded in the plasma D. Do not show cross-sensitivity with ester-linked local anaesthetics

24.3 The following is not true of local anaesthetics: A. The local anaesthetic is required in the unionized form for penetrating the neuronal membrane B. The local anaesthetic approaches its receptor only from the intraneuronal face of the Na+ channel C. The local anaesthetic binds to its receptor mainly when the Na+ channel is in the resting state D. The local anaesthetic combines with its receptor in the ionized cationic form

24.4 Local anaesthetics block nerve conduction by: A. Blocking all cation channels in the neuro-nal membrane B. Hyperpolarizing the neuronal membrane C. Interfering with depolarization of the neuro-nal membrane D. Both ‘B’ and ‘C’ are correct

24.5 Sensitivity of a nerve fibre to blockade by lignocaine depends on: A. Whether the fibre is sensory or motor B. Whether the fibre is myelinated or nonmyeli-nated C. Internodal distances in the fibre D. Both ‘B’ and ‘C’ are correct

2 4 . 2D 2 4 . 3 C 2 4 . 4 C 2 4 . 5D

24.6 A resting nerve is relatively resistant to blockade by lignocaine compared to one which is repeatedly stimulated because: A. Lignocaine penetrates resting nerve memb-rane poorly B. Lignocaine binds more avidly to the inactiva-ted Na+ channel C. Nerve impulse promotes ionization of lignocaine D. Nodes of Ranvier are inaccessible in the resting state

24.7 Which of the following is not the reason for greater susceptibility of smaller sensory fibres to blockade by local anaesthetics than larger motor fibres: A. Sensory fibres are inherently more sensitive than motor fibres B. More slender fibres have shorter internodal distances C. Small sensory fibres generate higher frequency longer lasting action potential D. Smaller fibres have shorter critical lengths for blockade

24.8 Which sensation is blocked first by low concentra-tions of a local anaesthetic: A. Pain B. Temperature C. Touch D. Deep pressure

24.9 Injection of adrenaline along with a local anaesthetic serves the following purpose: A. Lowers the concentration of the local anaes-thetic to produce nerve block B. Prolongs the duration of local anaesthesia C. Increases the anaesthetised area D. Reduces the local toxicity of the local anaes-thetic
ANSWERS
2 4 . 6 B 2 4 . 7 A 2 4 . 8 A 2 4 . 9 B

24.10 Adrenaline added to local anaesthetic solution for infiltration anaesthesia affords the following except: A. Prolongs the duration of local anaesthesia B. Makes the injection less painful C. Provides a more bloodless field for surgery D. Reduces systemic toxicity of the local anaes-thetic

24.11 The following local anaesthetic raises BP instead of tending to cause a fall: A. Cocaine B. Dibucaine C. Lignocaine D. Procaine

24.12 Toxicity of local anaesthetics involves the following organs except: A. Heart B. Brain C. Kidney D. Skin and subcutaneous tissue

24.13 The local anaesthetic with the longest duration of action is: A. Procaine B. Chloroprocaine C. Lignocaine D. Dibucaine

24.14 Which of the following is a poor surface anaesthetic: A. Procaine B. Lignocaine C. Tetracaine D. Benoxinate
ANSWERS
24.10 B 24.11 A 24.12 C 24.13D 24.14 A

24.15 The local anaesthetic having high cardiotoxic and arrhythmogenic potential is: A. Lignocaine B. Procaine C. Bupivacaine D. Ropivacaine

24.16 Which of the following statements is true for lignocaine: A. It is an ester-linked local anaesthetic B. It is not likely to exhibit cross-sensitivity with procaine C. It has a shorter duration of action than procaine D. It is not a surface anaesthetic

24.17 Low concentration of bupivacaine is preferred for spinal / epidural obstetric analgesia because: A. It has a longer duration of action B. It can produce sensory blockade without paralysing abdominal muscles C. It distributes more in maternal tissues so that less reaches the foetus D. All of the above are correct

24.18 The following local anaesthetic is poorly water soluble, PABA derivative and primarily used for anorectal lesions, wounds and ulcers: A. Benzocaine B. Dibucaine C. Procaine D. Benoxinate
ANSWERS
24.15 C 24.16 B 24.17D 24.18 A

24.19 Choose the local anaesthetic that is specifically used to produce corneal anaesthesia for tonometry: A. Tetracaine B. Oxethazaine C. Ropivacaine D. Benoxinate

24.20 Eutectic lignocaine-prilocaine has the following unique property: A. It causes motor blockade without sensory block B. By surface application, it can anaesthetise unbroken skin C. It is not absorbed after surface application D. It has strong vasoconstrictor action

24.21 Oxethazaine is used for anaesthetizing gastric mucosa because: A. It is not absorbed from the gastrointestinal tract B. It remains largely unionized in acidic medium C. It is highly ionized in acidic medium D. It produces no systemic effects even at high doses

24.22 Surface anaesthesia is used for the following except: A. Ocular tonometry B. Urethral dilatation C. Tooth extraction D. Anal fissure

24.23 In which of the following techniques the concentration of the local anaesthetic used is the lowest: A. Infiltration anaesthesia B. Nerve block anaesthesia C. Spinal anaesthesia D. Epidural anaesthesia ANSWERS
24.19D 24.20 B 24.21 B 24.22 C 24.23 A

24.24 The segmental level of spinal anaesthesia depends on: A. Volume of the local anaesthetic injected B. Specific gravity of the local anaesthetic solution C. Posture of the patient D. All of the above factors

24.25 In spinal anaesthesia the segmental level of: A. Sympathetic block is lower than the sensory block B. Sympathetic block is higher than the sen-sory block C. Motor block is higher than the sensory block D. Sympathetic, motor and sensory block has the same level

24.26 The duration of spinal anaesthesia depends on each of the following except: A. Which local anaesthetic is used B. Concentration of the local anaesthetic used C. Posture of the patient D. Whether adrenaline has been added to the local anaesthetic

24.27 The following factor is not involved in the causation of hypotension due to spinal anaesthesia: A. Histamine release B. Reduced sympathetic vasoconstrictor tone C. Decreased venous return from the lower limbs D. Bradycardia

24.28 Spinal anaesthesia is not suitable for: A. Vaginal delivery B. Lower segment caesarian section C. Prostatectomy D. Operations on mentally ill patients
ANSWERS
24.24D 24.25 B 24.26 C 24.27 A 24.28D

24.29 Epidural anaesthesia differs from spinal anaesthesia in that: A. Epidural anaesthesia produces less cardio-vascular complications B. Headache is more common after epidural anaesthesia C. Blood concentrations of the local anaesthetic are lower after epidural anaesthesia D. Greater separation between sensory and motor blockade can be obtained with epidu-ral anaesthesia

24.30 Intravenous regional anaesthesia is suitable for: A. Orthopedic manipulations on the upper limb B. Vascular surgery on the lower limb C. Head and neck surgery D. Caesarian section
ANSWERS
24.29D 24.30 A