851.Phenytoin
A.Is used for post herpetic neuralgia
B.Is a class I antiarrhythmic
C.Works by abolishing the primary discharging focus of seizures
D.Is only 40% protein bound
E.Is a potent enzyme inhibitor

852.Regarding the mode of action of opioid drugs
A.Kappa receptors may produce analgesia and euphoria
B.Delta receptors display selectivity for dynorphins
C.Opioid analgesic actions at omega receptors are blocked by naloxone
D.Opioid peptides activate synapses in the CNS and gut
E.Pentazocine predominantly binds to Kappa receptors

853.Benzodiazepines
A.Are primarily excreted unchanged in the urine
B.Decrease the frequency of the Cl-channel opening
C.Act upon GABAareceptors
D.All have shorter half-lives than flumazenil
E.Do not cross the placenta during pregnancy

854.Suxamethonium
A.Phase II paralysis may be overcome by acetylcholinesterase
B.Metabolism at the synapse is rapid
C.Low K is a relatively common S/E
D.Onset of action is approximately 4-8 minutes
E.Metabolism in the circulation is by specific cholinesterase

855.Regarding phenytoin
A.Small increases in dose can result in large increases in concentration
B.Apparent half-life increases because of drug accumulation in adipose tissue
C.With concentrations in the toxic range, once dosing is stopped concentrations drop rapidly to therapeutic
D.It demonstrates similar pharmacokinetics to lignocaine
E.Large dose adjustments are required to achieve concentrations in the therapeutic range

856.Regarding the opioid receptor, which is false
A.They are closely linked with the cAMP system
B.Analgesia at a supraspinal level results principally from kappa receptors
C.They are highly concentrated in the dorsal horn of thespinal cord
D.They may be involved with pain modulation
E.Sigma receptors are related to the hallucinogenic effects of opioids

857.Naloxone
A.Has an increased half life in the presence of renal failure
B.Does not produce an abstinence syndrome after withdrawalsubsequent to chronic administration
C.Is a weak opiate agonist/antagonist
D.Has a half life of 30 minutes
E.Binds specifically with kappa receptors

858.The cholinesterase inhibitor with the shortest duration of action is
A.Physostigmine
B.Edrophonium
C.Neostigmine
D.Parathion
E.Malathion

859.The half life of lignocaine is
A.1 min
B.5 min
C.10 min
D.30 min
E.120 min

860.Which of the following is a direct serotonin agonist
A.fluoxetine
B.Amitriptyline
C.moclobemide
D.ondansetron
E.sumatriptan