BENZODIAZEPINES.ppt - BENZODIAZEPINES HISTORICAL NOTES Widely used as sedative-hypnotics and anxiolytics Have supplanted the barbiturates Were 1st real

BENZODIAZEPINES.ppt - BENZODIAZEPINES HISTORICAL NOTES...

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BENZODIAZEPINES HISTORICAL NOTES Widely used as sedative-hypnotics and anxiolytics Have supplanted the barbiturates Were 1 st real selective anxiolytics by mechanisms not through sedation Were prototype real anxiolytics Barbiturates: though 1 st anxiolytics Not truly anxiolytics Cause sedation latter masking anxiety CHLORDIAZEPOXIDE 1st benzodiazepine synthesized in 1950s 1 st to be introduced clinically in 1960s Was more effective than barbiturates Had better safety margin Fatalities rare from overdose DIAZEPAM Marketed in 1963 Was 3-10 fold more potent than chordiazepoxide as anxiolytic Several others since marketed
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…Cont. Examples of long-acting BDZs Chlordiazepoxide, diazepam, prazepam and clorazepate Flurazepam and nitrazepam also have active metabolites with long t1/2 CLINICAL IMPLICATION OF LONG DURATION OF ACTION: 1. Cumulative effects on multiple dosing may occur 2. Excessive drowsiness may occur: Hang-over effect next day 3. Toxicity may occur, especially: the elderly hepato-compromized slow metabolizers
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…Cont . EXAMPLES OF SHORT-ACTING BDZs Estazolam, oxazepam, lorazepam…etc: Metabolized directly into inactive metabolites (glucuronides) Alprazolam, triazolam Also short acting THERAPEUTIC IMPLICATIONS OF SHORT ACTIVITY: Short-acting BDZs favoured as hypnotics But disadvantage: May be associated with: Daytime anxiety Tenseness or panic or Early morning insomnia next day form of withdrawal symptoms (since they are short-acting )
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…Cont. ADVANTAGES OF LONG-ACTING BDZs Less frequent dosing Less variation in plasma concentration Less severe withdrawal symptoms DISADVANTAGES OF LONG-ACTING BDZs Risk of drug accumulation Risk of daytime psychomotor impairment Risk of daytime sedation
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