Sedative Hypnotics. Isopropyl Alcohol H H H H OH H. H H Ethyl Alcohol (Ethanol)

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1 Sedative Hypnotics Alcohol - The most commonly used Sedative- Hypnotic. Probably the oldest psychoactive drug used by humans. Alcohol use is common our society. 2/3 of people drink. 10% are problem drinkers 5% are alcoholics What is alcohol? A compound composed of Carbons, Hydrogens, and a Hydroxy group. Ethyl alcohol is only one of many different alcohols. H H H H C C C H H OH H Isopropyl Alcohol H H H C C OH H H Ethyl Alcohol (Ethanol) 1

2 Production of ethanol Produced by fermentation. Yeast converts sugar (glucose) into ethanol. Type of sugar determines beverage. Fermentation is limited to producing 12% ethanol. Distillation produces higher ethanol concentrations (distilled spirits). Ethanol concentration measured in proof. Measuring the amount of ethanol in the body. Blood Alcohol Content (BAC) grams of ethanol / 1 ml of blood..001 g ethanol / 1 ml blood = 0.10% BAC 0.08 BAC - Legal driving limit in CA. Crude method for calculating 0.08 BAC 1 standard drink / 50 lbs. of body weight. 1 drink =.6 ounces of pure ethanol. 1.5 Ounce of distilled spirits. 5 Ounces of wine. 12 Ounces of beer. 2

3 Problems with estimating BAC Body weight isn t a good measure. Fat contains less ethanol. More fatty tissue = higher BAC. The standard drink may not be standard. Behavioral Effects of Ethanol Low Dose of Ethanol 0.05 BAC Disinhibition Light Impairment of judgement Lowered Alertness Feelings of Euphoria Behavioral Effects of Ethanol Moderate Dose of Ethanol 0.08 BAC 0.10 BAC Legally intoxicated in CA Slowed reaction times. Impaired motor coordination Gross judgement impairment. 3

4 Behavioral Effects of Ethanol High Dose of Ethanol 0.2 BAC Severe motor disturbances. Severe sensory disturbances. Memory Deficits Behavioral Effects of Ethanol Very High Dose of Ethanol 0.3 BAC 0.35 BAC 0.4 BAC Stupor. Surgical Anesthesia Unconsciousness LD50 by respiratory depression. Ethanol is a dangerous drug. Therapeutic Index is < 10 ED 50 of.05 BAC (or greater) LD 50 of.4 BAC 4

5 Pharmacokinetics of Ethanol Lipid soluble enough to be easily absorbed. Crosses the BBB easily. Not lipid soluble enough to dissolve into fat. Circulates until metabolized. Ethanol Absorption Stomach 10% Small intestine 90% Duration in the stomach can affect the onset of intoxication. Food Carbonation Ethanol Metabolism Ethanol Alcohol dehydrogenase Acetaldehyde Acetic Acid Aldehyde dehydrogenase HO 2 CO 2 5

6 Site of Ethanol Metabolism Stomach( 10%-20%) via alcohol dehydrogenase in stomach. Stomach metabolism is affected by: Duration of drug in stomach. Amount of alcohol dehydrogenase. Liver ( 80% - 90%) via alcohol dehydrogenase and other enzyme systems. First pass metabolism eliminates 40% of ethanol. Ethanol is metabolized at a fixed rate. Doesn t follow half-life rule. Limited by amt of alcohol dehydrogenase. BAC drops points / hour 1/4 drink for every 50 pounds of body weight. Pharmacodynamics of ethanol. Ethanol has a VERY low potency. Moderate dose of 30 grams. 1500X less potent than cocaine. This is evidence for very nonspecific effects. 6

7 Ethanol is a Dirty Drug. Membrane Fluidity Glutamate Antagonist GABA Agonist R GABA antagonist that reverses ethanol intoxication. Acutely facilitates opioid release. Naltrexone (ReVia) as treatment of alcholism. Facilitates dopamine release. Other notable physical effects: Suppresses release of antidiuretic hormone (ADH). ADH causes the kidneys to retain water. So the effect of suppressing ADH is... Acute Toxicity Death through respiratory depression. Vomiting or passing out usually prevents death. Consuming large amounts very quickly can defeat this protective mechanism. 7

8 The dreaded hangover Symptoms: Headache Thirst Body Aches Nausea and Vomiting Possible causes of Hangovers Toxic byproducts of ethanol metabolism. Acetaldehyde Congeners Dehydration Digestive Tract Irritation Sleep Deprivation Acute Ethanol Withdrawal? hair of the dog that bit you Chronic Toxicity Liver Disease Alcohol-Related Fatty Liver Alcoholic Hepatitis Normal Liver Cirrhosis (scarring) 75% of alcohol related deaths. Cirrhotic Liver 8

9 Chronic Toxicity continued... Brain Damage - Heavy, chronic use probably leads to death of brain cells. Chronic Toxicity continued... Organic Brain Syndromes Wernicke s Disease Confusion and deficits of coordination. Caused by a vitamin (thiamin) deficiency. Korsakoff s Psychosis Loss of memory for recent and new events. Confabulation Brain Damage continued... Besides organic brain syndromes are there less obvious impairments? No effect on Verbal Intelligence. Deficits in Abstract Reasoning. Visual-Spatial Abilities Logical Thinking Cognitive Shifts Card Sorting Tasks 9

10 Other examples of chronic toxicity Damage to most other organs. Heart Pancreas Sex Hormone Production Cancer, especially when combined with tobacco use. Harm to the fetus. Beneficial Effects of Ethanol 1-2 drinks a day might prevent heart disease and strokes. Reduces blood clotting. Raises HDL cholesterol. Psychological benefits? However, risk due to accidents, cancer, etc negate all or most of this benefit. Tolerance, Addiction, and Withdrawal Tolerance developed from regular use. Due to all 3 mechanisms. WARNING: Tolerance to lethal effects develops slower than tolerance to other effects. 10

11 Psychological and Physical Dependence Alcoholics account for 20% of people treated by psychiatric facilities. Animals will self-administer. Promotes DA transmission in nucleus accumbens. Ethanol withdrawal can be serious. Starts within a day and lasts for 1-2 weeks. Mild symptoms of ethanol withdrawal: Anxiety, Tremor, Rapid Heartbeat, Insomnia Serious symptoms of ethanol withdrawal (5-10%) Delirium Tremens (DTs) Hallucinations, Delusions, Seizures About 30% of untreated DTs are fatal. Preferred treatment for DTs: Long acting benzodiazepine (e.g., diazepam) before DTs develop. Barbiturates Earliest medically prescribed sedativehypnotic. Originally used to reduce anxiety, produce sedation and anesthesia. 11

12 3 barbiturate categories determined by lipid solubility and fat depot binding. Category Onset Duration Example Ultra short 10-20s min Thiopental Acting (Pentothal) Intermediate min 5-8 hrs Pentobarbital Acting (Nembutal) Long Acting 1+ hrs hrs Phenobarbital (Luminal) Pharmacokinetics determine clinical use. Class Ultra short Used for/treats preanesthesia Intermediate anesthesia, insomnia (formerly) Long Acting seizure disorders, anxiety (formerly) Safety Barbiturates are fairly dangerous. High Risk of overdose (low TI). Risk is much higher when combined with other sedative-hypnotics. Shared pharmacokinetic and pharmacodynamic features. Strong potential for tolerance and addiction. Medical use has greatly diminished. 12

13 Mechanism of action of barbiturates. GABA binding normally causes Cl- influx and IPSPs. At low-moderate doses, barbiturates increase the duration of Cl- channel opening. At high doses, barbiturates activate GABA receptor directly. Inhalants - Psychoactive substances that are volatile (a gas) at room temperature. Categories of Inhalants Gas Anesthetics (e.g., Nitrous Oxide, Halothane) Easier and safer than barbiturates for general anesthesia. Inhalants of Abuse Solvents (glue, paint thinner, correction fluid. Aerosols (hair spray, butane) Anesthetics (nitrous oxide, halothane) 13

14 Inhalant abuse can cause: Euphoria Hallucinations Ethanol-like intoxication High doses or chronic use can cause: Heart or liver failure. Anoxia (lack of oxygen to brain) Seizures Brain Damage Date-Rape Drugs Flunitrazepam (Rohypnol) Benzodiazepine used in other countries as a sleep aid. Very potent. Defensive beverage selection. Gamma Hydroxy Butyrate (GHB) Endogenous neurotransmitter. Can be illegally synthesized. May be useful for narcolepsy. These drugs exert classic sedative-hypnotic effects. Euphoria Disinhibition Amnesia (Blackouts) Unconsciousness Respiratory Depression Effects are greatly enhanced when mixed with alcohol. 14