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72 Cards in this Set
- Front
- Back
General depressants which decrease CNS activity at low doses
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Barbiturates
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Decrease neural and skeletal muscle activity at higher doses
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Barbiturates
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Block activity in reticular activating system thereby producing sedation and inducing sleep
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Barbiturates
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Barbiturates block activity in the __ thereby producing sedation and inducing sleep
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reticular activating system
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Barbiturate with the longest half-life
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Phenobarbital
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Barbiturate with an intermediate half-life
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Butabarbital
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Barbiturates enhance __ receptor activity
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GABAa
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Barbiturates increase Cl- conductance as with benzodiazepines, however
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through a separate site
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inhibits GABA transaminase
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Thiopental
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Enzyme responsible for inactivation of GABA
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GABA transaminase
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At low doses, barbiturates block __ excitation
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glutamate receptor-mediated
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At high doses, barbiturates
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Block K+ and Na+ channels
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Net effect of a barbiturate is enhancement of __ and blockade of
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inhibitory neurotransmission;
excitatory neurotransmission |
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Barbiturates are anxiolytic, but with substantial
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drowsiness and ataxia
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Barbiturates depress higher cortical centers, resulting in
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euphoria
impaired judgment giddiness excitement |
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barbiturates have this effect on body temp
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decrease it
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barbiturates have this effect on monosynaptic reflexes
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none
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why don't barbiturates have an effect on monosynaptic reflexes
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not centrally active muscle relaxants
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do barbiturates have analgesic activity
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no
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Barbiturates depress respiration increasingly with
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increasing doses
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Very high doses of barbuiturates result in collapse of
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vasomotor center
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Barbiturates depress sympathetic ganglia activity which has this effect on bp
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decrease blood pressure
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barbiturates induce liver microsomal enzymes which
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alters drug metabolism
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Metabolism of barbiturates is achieved this way
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in the liver by oxidation
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barbiturates are generally well absorbed from
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GI tract and muscle
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Oxybarbiturate (e.g., phenobarbital) onset parallels
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rate of absorption
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Oxybarbiturate duration of action parallels
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rate of elimination
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Thiobarbiturate (e.g., thiopental) onset and duration of action related to
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distribution
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Rapid distribution to brain due to high lipid solubility thus rapid onset of action
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thiobarbiturates
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thiobarbiturates have rapid distribution to brain, but slower distribution to
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muscle and fat tissues
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Usefulness of barbiturates for anxiolysis is limited by
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low selectivity
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use of barbiturates as anxiolytics
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Pre-anesthetic to reduce anxiety
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barbiturates are effective hypnotics; however...
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other medications are more selective
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problem assoc with use of barbiturates for anticonvulsant activity
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Respiratory depression
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barbiturates decrease __ associated with surgery or head injury
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cerebral edema
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barbiturates are useful in treating __ arising from disease or poisoning
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acute seizures
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Idiosyncratic effects of barbiturates are seen mainly in these patients
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geriatric and debilitated
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Common ADRs of barbiturates are just extended __ effects
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CNS depressant
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Uticaria
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hives
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swelling in deep layers of skin
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Angioneurotic edema
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scaly skin disorder
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Exfoliative dermatitis
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lesion resulting from death of liver parenchymal cells, resulting in jaundice
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Parenchymatous hepatitis
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in a few cases, barbiturates result in __; a blood disorder involving loss of white blood cells
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Agranulocytosis
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dose of barbiturate which results in poisoning
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5 – 10x therapeutic dose
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dose of barbiturate which results in death
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15 x therapeutic dose
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Stupor or coma
Respiratory depression Circulatory collapse are all sx of |
barbiturate toxicity
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can be used as a supportive measure in treatment of barbiturate toxicity
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Dopamine
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Altered porphyrin synthesis
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Porphyria
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with barbiturates, tolerance develops to CNS depressant effects in this amount of time
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within a few weeks
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Chronic use of barbiturates has this effect on GABAa receptor
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down-regulation
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are barbiturates habit-forming?
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yes!
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dependance of an individual to barbiturates are both
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psychological and physical
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Withdrawal from barbiturates is more dangerous than withdrawal from
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opiates
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GABAA receptor down-regulation leads to __, which persists following drug withdrawal
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elevated central cholinergic activity
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The net effect of abstinence from barbiturates
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CNS excitation
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treatment for abstinence syndrome with barbiturates
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Hospitalization and stabilization on lowest dose that prevents abstinence syndrome
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Gradual withdrawal from barbiturates happens over this period of time
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2 – 3 weeks
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Substitution with __ to treat abstinence sydrome is not recommended
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non-barbiturates
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benzodiazepines and barbiturates are generally
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sedative hypnotics
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Chloral hydrate
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Noctec
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Methyprylon
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Noludar
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Glutethimide
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Doriden
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Ethinamate
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Valmid
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Methaqualone
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Sopor® Parest® Quaalude
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Ethchorvynol
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Placidyl
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Chloral hydrate is metabolized by
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alcohol dehydrogenase
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active metabolite of chloral hydrate
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trichlorethanol
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trichloroethanol is further oxidized to
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trichloroacetic acid
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Trichloroethanol half life is
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8 hrs
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Superior to barbiturates with respect to modifying sleep patterns, REM rebound
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Chloral hydrate
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When combined with ethanol, chloral hydrate rapidly and effectively
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promotes sleep
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chloral hydrate slows ethanol metabolism, thereby
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enhancing effects of ethanol
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