Pharmacology Notes - Flumazenil and Barbiturates - PDF

Fluma azenil_ Flumazzenil is a competitiv c ve antago nist at be enzodiazep pine recepttors. It is used to prevent or reverrse the CN NS effectss from beenzodiazep...

Fluma azenil_ Flumazzenil is a competitiv c ve antago nist at be enzodiazep pine recepttors. It is used to prevent or reverrse the CN NS effectss from beenzodiazep pine overd dose or to o speed recovery from th he effects of benzo odiazepines s used in anestheticc and dia agnostic proced dures. Precautions: avvoid BDZ use u in the ffollowing conditions: c : – Drivvers and machine m woorkers neeeding high attention. – Pre egnancy an nd lactatio on: fetal m muscular hypotonia anda impairred suckling may occ cur. – Hep patic ence ephalopathy. – Resspiratory depression d. – Com mbination with otherr CNS dep ressants e.g. e alcohol. 2. Bus spirone  It iss partial agonist on 5--HT1A rece eptors in th he midbrainn.  Sele ective anxiolytic with hout hypno otic or mus scle relaxant effect.  It su uppresses anxiety affter a long delay (2 or more weeks).  It iss the anxiolytic of cho oice in the elderly.  No liability forr drug dependence.  Adv verse effects include e dizzinesss, headach he, tachycaardia and nnervousne ess. 3. Barrbiturates s  Barrbiturates have h been largely re eplaced by y the more e safe benzzodiazepin nes and the SSRIs, forr the treatm ment of an xiety and sleep s disorders.  Pheenobarbitaal is a long acting bbarbituratee (~6-8h) used u as ann anticonv vulsant; opental is ultrashort agent (~15 thio 5-20 min) used u as an n i.v. generral anesth hetic. Mecha anism of action a  Barrbiturates have eithe er GABA-llike action n OR enhance the t effects s of GABA A at GABAA eptors ressulting in ↑ Cl- co nductance rece e and d hyperpolaarization.  Thee action off barbitura ates is non n-selective e i.e. increasing g the dos se of barb biturates → genneralized CNS and me epression. edullary de 341  Therap peutic use es  As sedative and hypn notics in the treatm ment of in nsomnia. They are largely replaced by benzodiaze b epines.  Phe al is used in the treattment of grand mal epilepsy. enobarbita e  Phe al is micro enobarbita osomal en nzyme ind ducer. It is s used in the treatm ment of hypperbilirubinaemia in neonates n (p physiologic cal jaundicce) to activvate liver enzymes (glu ucuronyl traansferase) and fasten n metaboliism of bilirubin.  Thio opental iss used as short s naesthetic in short prrocedures.. i.v. an Advers se effects – Phyysical depe endence. spiratory and myo – Res ocardial pression (in acute toxicity) dep enobarbital – Phe is hepatic crosomal enzyme inducer. mic – Pheenobarbital may increase porrphyrin synthesis. s It can preccipitate th he sympttoms of acu ute intermitttent porph hyria. 4. Ram melteon  Ram melteon is prescribe ed for patiients who have difficulty fallinng asleep.. It is a sele ective agonist at me elatonin MMT1 and MT2M recepttors that aare involved d in the promotion of sleep and that mainttain the noormal circadian rhyth m.  Advverse effects include e dizzinesss and fatig gue. 5. Chloral hydrrate  It iss one of thee oldest hyypnotic druugs. It is an n alcohol derivative. d  It prroduces hyypnosis in 30 min annd last for 6 hrs.  It iss used maainly as a hypnotic i n children n and elderly before short surgical or den ntal proced dures but itts use now w is very lim mited. 342