personal and social concerns of drug-taking behavior in Coos Bay oregon. Just from the link belowDue in Two Hours
“How strange would appear to be this thing that men call pleasure! And how curiously it is related to what is thought to be its opposite, Pain!
Wherever the one is found, the other follows up behind.”
Plato, Phaedo, fourth century B.C.
http://www.youtube.com/watch?v=uMBozVgO77A
Necro - I Need Drugs
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Terminology
Pharmacology – science of how drugs affect the body
Psychopharmacology – how drugs affect the brain and behavior
Pharmacokinetics – basic principles of drug absorption,distribution,metabolism and excretion.
Pharmacodynamics – interaction of the drug with its receptor or other cell functions
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Names of drugs
Chemical name – using the chemical jargon, i.e. 7-chloro-1,3-dihydro-1-methyl1-5phenyl1-2H-1,4-benzodiazepin-2-one.
Generic name – diazepam. Textbooks use the generic name.
Trade name – property of the company that sells the drug. In this case, the trade name is Valium
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PHARMACOKINETICS
DOSAGE
use metric system
ROUTES OF ADMINISTRATION
Injection (intravenous, intramuscular, or subcutaneous injection)
Inhalation (smoking)
Oral administration (by mouth)
Absorption through the skin or membranes (intranasal sniffing, sublingual absorption, rectal suppository, transdermal patch)
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Dosage
Use the metric system: a milligram is 1/1,000of a gram. ( a little over 28 grams in 1 ounce)
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Dosage continued
Doses are therefore reported in terms if milligrams per kilogram (kg) of body weight. A kg is 2.2 pounds)
LSD is the exception. Reported in micro grams
1 gr of LSD = 4,000 hits (McKim,1987)
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Dose Response Curves DRC
Necessary to give a range of doses
Range needs to cover a dose so low that there is no detectable effect and a dose so high that increases in dose have no further effects (McKim,1987)
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DRC continued
Plot the effects on a plot
Dose is reflected on the horizontal axis
Effect is plotted on the vertical axis
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The majority of clinical benefit is achieved at low doses, after which the efficacy curve begins to flatten out.
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DRC characteristics
Potency – how much is required to get a response
Efficacy - maximum effect obtained
Variability – individual differences in drug response
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Effectiveness of drugs
Use ED (effective dose) and LD (lethal dose)
Drugs’ toxicity is measured by looking at the ratio of lethal and effective dose
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EFFECTIVE DOSE (ED) LETHAL DOSE (LD)
The effective dose (ED) is the minimal dose necessary to produce the intended drug effect in a given percentage of the population under study
The lethal dose (LD) is the minimal dose necessary to produce death in a given percentage of the population under study
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Effectiveness of drugs continued
The ratio of LD50/ED50 is called the therapeutic index
Margin of safety – another ratio which uses 1% and 99% - the higher the ratio, the safer the drug
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AN EXAMPLE OF ED-RESPONSE AND LD-RESPONSE CURVES THAT WOULD PRESENT SERIOUS TOXICITY PROBLEMS
Allyn and Bacon
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Examples of LD
Nicotine - LD50 (in mice) orally is 0.23g/kg
Caffeine – 250mg/kg in mice; 70 to 100 cups of brewed coffee (Barnes,1973)
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EXAMPLES continued
Cocaine – depends on route of administration
The LD50 in a 150 pound man is about 500 mg
When it is taken intranasally,however,the LD50 may be as low as 30 mg.(Crowley, 1987)
(Related to sudden increase in drug levels in the brain)
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More examples
Amphetamine deaths – the lethal dose ranged from 5 mg to 630 mg (O.J. Kalant,1973)
Barbiturates – 4,000 to 6,000 mg is the estimated lethal dose. (Moeschlin,1971)
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EXAMPLES continued
Alcohol – blood alcohol level of about 500 mg per 100 ml – probably a lethal dose for most people ( 25 ounces of liquor)
LSD – 0.3 mg/kg I.V. for mice,rats, and rabbits. It is, in the toxic sense, one of the safest drugs known
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Poisons
Botulinum toxin A
5g – about a teaspoonful could kill a quarter of the world’s entire current population.
1 out of 4 persons alive today
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Poisons continued
Tetanus toxin
1 teaspoon could kill about 7 million people
Sarin (nerve gas) – 0.01mg/kg
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Remember
Drugs do not create any unique effects- they merely modulate normal neuronal functioning – they mimic or antagonize the actions of a specific neurotransmitter.
(Julien,R.2001)
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Factors influencing Drug Responses some of these you listed this morning in class!
Route of administration Dose
Other drugs Genetics
Gender Age
Health Weight
Biorhythms Mood
Setting Tolerance
Expectancy Learning
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Many Factors
Affect Drug
Response
MERCK MANUAL
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Tolerance (McKim,1987)
Cross Tolerance- tolerance to one drug may diminish the effect of another drug (i.e. opiates)
Behavioral tolerance/conditioned tolerance
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Tolerance
Metabolic tolerance – metabolism increase (i.e. enzyme induction to destroy the drug)
Cellular or pharmacodynamic tolerance
( body makes adjustments to maintain homeostasis)
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Tolerance
Acute tolerance – i.e. alcohol- effects of alcohol are more pronounced while the BAL is rising
( Vogel-Sprott,1992)
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Half-life of a drug
Time it takes for half the dose to be eliminated from the body
need to maintain steady-state level (i.e. prescription medication)
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Half-life calculations
Amount of drug in the body
Number of half lives % eliminated % remaining
0 0 100
1 50 50
2 75 25
3 87.5 12.5
4 93.8 6.2
5 96.9 3.1
6 98.5 1.6
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Examples
Aspirin ca. 1 hr
Morphine ca 2 hours
Lithium 24 hours
Valium several days
Assuming liver and kidneys are up to par!
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http://www.youtube.com/watch?v=mp93nPUzHqM
A good video on pharmacokinetics
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“
How strange would appear to be this thing that
men call pleasure! And how curiously it is related
to what is thought to be its opposite, Pain!
Wherever the one is found, the other follows up
behind.
”
Plato,
Phaedo,
fourth century B.C.
http://www.youtube.com/watch?v=uMBozVgO77A
Necro
-
I Need Drugs