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Chapter 10 - Sedatives
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Sedative-Hypnotics: calm us down and produce sleep Antianxiety Drugs: tranquelizers
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Acute Effects From normal to coma and death Low doses: relaxation; euphoria; disinhibition of cerebral cortex (like having a few drinks) As dose levels increase: lower brain regions are affected Therapeutic doses: sedated and drowsy; impairs motor performance
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Main use: was to treat insomnia; significantly depresses REM; REM rebound With alcohol-synergistic effects All barbs: agonists of GABA
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Chronic Effects Tolerance develops-may experience anxiety and insomnia at original dose Both phramacodynamic and metabolic tolerance Withdrawal: tremors, nausea & vomiting, sweating, general confusion, convulsions, hallucinations, fever, elevated heart rate May be life-threatening-approx. 5% chance of death without med supervision
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Current medical uses: epileptic seizures; convulsions Dependence potential: lab animals-self- administer at rates equal to coke Use peaked in 1950s & 1960s U. of Mich survey-hs seniors-2008-9% lifetime; 1975-17% lifetime; 2008-6% within past year; 1975-11% within past year
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Nonbarbiturate Sedative-Hypnotics Chloral hydrate-1832-a depressant used for treating insomnia Not as great an effect on REM as barbs Very irritating to stomach Synergistic effects with alcohol “Mickey Finn”-a few drops in glass of whiskey
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Methaqualone: Quaalude; Sopor 1965 1970s-recreational use spread 1984-Schedule I Still available-underground labs; imported
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Anxiety Disorders Six major types: panic disorder, obsessive- compulsive disorder, post-traumatic stress disorder, specific phobias, social phobias, generalized anxiety disorder First antianxiety drug-meprobamate (Miltown)- 1955 Became a household word First drug in history to be marketed as an antianxiety drug; actually produces sedation; both physical and psych dependence; Schedule IV – very infrequently prescribed
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Benzodiazepines
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Acute Effects Relatively slow absorption-effects more gradual than barbs (absorbed through small intestine; barbs through stomach) Do not affect respiratory centers in medulla; 50-60 times the normal dose won’t stop breathing Dangerous with alcohol
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Elderly-slowed elimination-dangerous build- up: drug induced dimentia: confusion and loss of memory All ages: drowsiness and poor coordination- driving is dangerous Problems learning; can prevent brain from recording and adapting to new information Amnesia-Rohypnol (roofies)-much more potent than valium-2 mg in drink
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Chronic Effects Tolerance to sedative effects No tolerance to antianxiety effects at therapeutic doses Withdrawal-high anxiety, insomnia, restlessness, agitation Psychological dependence-the real problem
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Effects on Brain
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Agonist of GABA 3 binding sites: sedative-hypnotics; barbs; benzodiazepines; benzodiazepines and alcohol GABA attaches to binding site; if benzodiazepines are occupying the site; greater inhibition
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Receptors: primarily in limbic system and cerebral cortex Limbic system: antianxiety action Cerebral cortex: sedation
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Drugs Designed Specifically to Induce Sleep Ambien: 1993 Chemically unrelated to benzodiazepines; but act on a benzodiazepine receptor that induces sleep Doesn’t reduce anxiety; little or no relaxation Short half-life: 2 hours Should be used 7-10 days Lower abuse potential than benzos.
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Sleepwalking, binge eating, and driving without remembering Lunesta: 2005 Also not a benzodiazepine but acts on receptors to induce sleep Lower abuse potential than benzodiazepines
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GHB gamma –hydroxybutyrate Odorless, colorless liquid Europe: general anesthetic Used by bodybuilders; sales banned in 1990 Still available by prescription-narcolepsy Pharmacologists think GHB may be a neurotransmitter; synthesized in brain; has specific receptor sites; effects can be blocked by antagonists
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Produces relaxation, mild euphoria, then headache, nausea, drowsiness, loss of consciousness, seizures, coma, death Not addictive at therapeutic doses; problems at higher doses Routine tox screens in Ers-not set up to detect GHB; tell medical personnel if taken Very dangerous with alcohol; additive; lower blood pressure and decrease blood oxygen
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Tolerance and Withdrawal very serious problem: users learn that you get a high like alcohol; sedation at higher doses Use recreationally for euphoria; uses as sedative for falling asleep; may reach point where using every few hours, 24 hrs a day Withdrawal: very severe
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Insomnia, anxiety, psychosis; like alcohol Tremors, high heart rate, high blood pressure Should be done under medical supervision
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