IV diazepam has which of the following effect which is not seen by other routes ?
Ans. is 'd' i.e., Coronary dilatation Mechanism of action of benzodiazepines (BZDs) Benzodiazepines act preferentially on midbrain ascending reticular formation (which maintains wakefulness) and on limbic system (thought and mental function). Muscle relaxation is produced by action on medulla. Ataxia is due to action on cerebellum. BZDs acts on GABAA receptors. GABA,,, receptor has 5 subunits a / p, p, a / y. GABA binding site is on p. subunit, while BZDs binding site is on a / y subunit. BZDs receptor increase the conductance of Cl- channel. BZDs do not themselves increase Cl- conductance, i.e. they have only GABA facilitatory but no GABA mimetic action. (Barbiturates have both GABA facilitatory and GABA mimetic actions). Effect on CNS In contrast to barbiturates, BZDs are not general depressant, but exe relatively selective anxiolytic, hypnotic, muscle relaxant and anticonvulsant effects. The antianxiety action of BZDs is not dependent on their sedative propey --> with chronic administration relief of anxiety is maintained, but drowsiness wanes off due to development of tolerance. Stage 2 sleep is increased, while REM, Stage 3 & 4 sleep are decreased. Nitrazepam is the only benzodiazepine, which increases REM sleep. Clonazepan and diazepam have more marked muscle relaxant propey. Clonazepam, diazepam, nitrazepam and flurazepam have more prominent anticonvulsant activity than other BZDs. Diazepam (but not other BZDs) has analgesic action. Diazepam produces sho lasting coronary dilatation on i.v. injection. Diazepam decreases nocturnal gastric secretion and prevents stress ulcers.
Analgesia
Sedation
Hypotension
Coronary dilatation