621.Doxycycline
A.acts to inhibit nucleic acid synthesis
B.may cause photosensitivity

622.All of the following inhibit nucleic acid synthesis except
A.norfloxacin
B.trimethoprim
C.rifampicin
D.sulfasalazine
E.chloramphenicol

623.Gentamicin (2 CORRECT)
A.is not nephrotoxic
B.increases the effect of neuromuscular junction blocking drugs
C.may be given orally
D.enters cells by an oxygen dependent influx
E.has a large therapeutic index

624.Regarding trimethoprim, which is false
A.It is uselful in the treatment of UTI
B.It is bactericidal
C.It is an antifolate, anti-metabolite drug

625.Which can cause hypoprothrombinaemia
A.Cefuroxime
B.Cefotetan
C.Cefazolin
D.Cefaclor
E.Ceftriaxone

626.Regarding propranolol which is correct
A.It antagonizes catecholamines at α-and β-adrenoreceptors
B.It stimulates renin secretion by catecholamines
C.It increases plasma TGs
D.It increases plasma HDL
E.It blocks β1receptors in bronchial smooth muscle

627.Regarding Amiodaronewhich is false
A.It causes hyperthyroidism
B.It achieves higher levels in cardiac tissue than plasma
C.It is a non-competitive α blocker
D.It has a half life of 24hours
E.It markedly prolongs the QT interval

628.Important effects of digoxin on heart muscle include
A.Increased force of contraction
B.Decreased AV conduction velocity
C.Increased ectopic automaticity
D.Decreased ejection time
E.All of the above

629.The effects of digoxin include all except
A.An increase in cardiac intracellular K+
B.An increase incardiac intracellular Na+
C.An increase in cardiac intracellular Ca2+
D.An increase in cardiac contraction
E.A reduced sympathetic outflow to the heart

630.Regarding lignocaine which is correct
A.It lengthens the action potential duration by blocking Na channels
B.Thedose does not need to be altered in liver disease
C.It is limited in its use by the high rate of cardiotoxicity
D.Its clearance is reduced by cimetidine
E.It is a class IC antiarrhythmic

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