Alcohol/Hypnotics Flashcards
Alcohol- Pharmacokinetics (absorption, bio-availability, distribution, metabolism)
(1) Rapid absorption from gut, peak in 40 minutes “on an empty stomach”
(2) Optimum concentration for bio-availability is around 20% EtOH
(3) Distributes easily to all tissues (volume of distribution = 0.7L/kg)
(4) Metabolized mainly in the liver, but some is metabolized in the gut, particularly in men.
T/F The bio-availability of alcohol depends on the percentage of alcohol and the preparation that you are using.
TRUE; on an empty stomach you’ll get a different bio-availability whether you’re drinking beer, wine, spirits, etc.
Equivalents of alcoholic beverages (beer vs. distilled spirits; male vs. female)
- Consuming 12 fl. oz. of beer produces the same blood ethanol level as consuming 1 fl. oz. of distilled spirits (~20%)
- Males blood ethanol level after consuming the same beverage is ~4-5mg/dl less than when women consume the same amount of alcohol
T/F Alcohol metabolism is first-order mechanics.
FALSE; zero-order (i.e. a fixed amount per unit time (7-10 g/hr))
T/F Alcohol has no half-life.
TRUE
What are the two enzymes that work to break down alcohol? Where are they located? Why does the body need the second enzyme?
Alcohol dehydrogenase and Acetaldehyde dehydrogenase; they are located in the liver; the body uses Acetaldehyde dehydrogenase to convert acid aldehyde (a toxic acid byproduct from alcohol dehydrogenase) into acetate (used for metabolism in Kreb’s cycle).
Alcohol- Pharmacodynamics (Acute CNS effects- 4)
(1) Continuous CNS depressant, like general anesthetics and barbiturates
- low concentrations depress the reticular activating system and those parts of the cortex involved in highly integrated functions
- initial phase succeeded by general impairment of nervous function
- high concentrations (>300 mg/dL) cause general anesthesia (NOT GOOD THOUGH)
(2) CNS effects are generally in proportion to the concentration of alcohol in blood
(3) Anticonvulsant- in amounts that cause general CNS depression but it followed by a long period of hyper-excitability
- alcohol withdrawal in heavy users may cause seizures
(4) Enhancement of CNS depression occurs with sedatives, hypnotics, or tranquilizers
How much of alcohol is metabolized in the liver? What about an alcoholic/barbiturate user?
- 90%
- Alcohol/barbiturate user will have an induction of P450 enzymes that will bump of up metabolism of alcohol twice as much as a non-alcohol user; does effect metabolism of other drugs (alcoholic will metabolize barbiturates faster)
T/F Alcohol is indicated in epilepsy
FALSE; contraindicated because there is a high period of hyper-excitability
Correlates of Blood Alcohol Concentration (BAC)- What happens when you drink alcohol and drive a car? What percentage of people are considered “drunk” in this situation?
- When your BAC is 50 mg/dL (0.05) then you are twice as likely to get in a road accident, yet only 15% of the people are considered “drunk”
- As you drink more, the risk gets extremely high and the percentage is still low-
Alcohol- Pharmacodynamics (Other effects-7)
(1) Good topical antiseptic
(2) Respiration- ventilatory response to CO2 is depressed; respiratory depression can be dangerous
(3) G.I. tract- pronounced increase in gastric juices (contraindicated in peptic ulcer); also causes spasming in the gut
(4) Kidney- diuretic effect due to inhibition of pituitary secretion of ADH
(5) Liver- accumulation of fat in liver caused by - increased NADH/NAD ratio and mobilization of fat from peripheral tissues
(6) Cardiovascular: Vasodilation- moderates doses
(7) Physical dependence- big thing!
What are the 3 types of tolerance with alcohol?
(1) Metabolic- associated with increased metabolism, inducible enzymes in the liver, esp. microsomal oxidizing enzymes
(2) Functional- most of the PD effects of EtOH are due to the fact that EtOH changes the lipid environment of cell membranes, “fluidizes.” Changes the functional properties of many membranes. Chronic EtOH leads to more rigid membranes, more EtOH for the same effect.
(3) Behavioral- recovery of the ability to function socially in spite of the drug. May refer as much to how others perceive the drug user.
What is the abstinence syndrome? (consequences of dependence)
A physical consequence; it is the opposite of what the drug does to the body
What is the psychological consequence of dependence?
It leads to “purposeful behavior,” a condition where sustaining a dependence becomes a primary motivational factor. The person seems the need to always seek the drug.
What is the etiology of Alcoholism? Do genetic factors exist?
Behavior that establishes a pattern of tolerance, physical dependence, and withdrawal avoidance; Animal models suggest genetic factors exist.
