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Drugs and Our Society
The Physiological Impact of Drugs
Part 5
1.
2.
How drugs impact the physical
aspects of the body
Timing
- how often drugs are taken
- once a drug is taken there is a latency
period
Concentration of the drug is increasing in the
blood
- but not high enough to feel effects of drug
- many times you can feel the drug sensation
building
- you may feel warm / your skin is tingling /
your head feels as if it is expanding
How long is this latency period?
1.
2.
3.
4.
It depends on the absorption time of the drug
- as concentration of the drug continues to
rise
- effects become stronger
Even when maximum effect is reached
- concentration can continue to rise
Alcohol:
- drink and visit
- feel giddy and uninhibited
- you are becoming intoxicated
Maximum effect is reached when you pass out
- concentration continues to rise = death
latency period, cont
5.
6.
Timing is important
- whether a prescription drug or an illicit
drug
Both can result in a toxic effect
- either an overdose or death
Drug Interactions
This refers to the effects of two or more
substances
- also called a ‘polydrug’
- they can be additive / antagonistic / or
synergistic
- 25 % of emergency room admissions are
for alcohol + medications
2. Additive effect
- combination of drugs are purely additive
- one a value of 4 / other a 6 / additive effect
equals 10
- aspirin + pain reliever have a greater effect
1.
Antagonistic Effect
1.
2.
3.
Effect of one drug is diminished or
negated when combined with another
One has a value of 6 / second value of a 4
- effective value of a 3
- drug has been diminished
- Valium and Librium diminish the value of
oral contraceptives
Using the antibiotic tetracycline with milk
or antacids
- negates the antibiotic
Synergistic Effect
1.
2.
3.
The total effect is greater than the sum of
their individual effects
The action of two or more agents
- synergism: enhanced / unpredictable
effect
- caused by combining two or more
substances
- such as barbiturates and alcohol
Hyperadditive effect
- produce greater effect than administered
separately
Synergistic Effect, cont
3.
4.
- one drug may double or even triple the
effect of another
Potentiation
- one drug will have no effect
- unless taken with another drug
One drug with no effect
- combined with a drug value of 6
- potentiation effect equals a 10
Factors influencing the effects of
drugs
1.
Age
- infants and elderly are more sensitive to
drug effects
- elderly makeup 12% of the population
but take between 1/4th and 1/3rd of all
prescription drugs
- 2 of every 3 senior citizens aged 65 and
older take one or more daily
- tolerance for alcohol lessens as you age
- BAC’s are higher / less bodily fluids
Factors, cont
2.
- as people age, the percent of body fat
increases
- some drugs accumulate in adipose tissue
- this increases sensitivity to those drugs
and a toxic reaction can occur
Gender
- females and males respond differently to
drugs
- the differences are related to water and
body fat
Factors, cont
-
-
women who weigh the same as men have
higher percentage of body fat
and a lower percentage of water
this makes women more sensitive to drugs
fat stores drugs
water dilutes the amount of drug in the
bloodstream
hormones also make a difference
PMS / pregnancy
Factors, cont
3.
4.
Dosage
- already discussed the ED and LD
- the smallest amount of a drug required
to produce the desired effect
- is called the “threshold dose”
Purity and potency
- purity: the quality of a substance / the
state of non-contamination of a drug
- potency: ability to produce an effect
relative to other drugs (the less needed
to produce a response, the more
potent the drug)
Factors, cont
5.
6.
Many health problems that users experience
are due to the purity of a drug
- the quality varies greatly in illicit drugs
- it becomes a significant factor in the drug’s
effect
A DEA report on heroin:
- purchased in the mid-1970’s: 6% purity
- early 1980’s: less than 4% purity
- early 1990’s: more than 20% purity
- today: it ranges from 20% to 90%
depending on the location
Factors, cont
7.
8.
Potency
- looking at heroin / morphine / and aspirin as
pain relievers (?)
- heroin is the most potent
- next is morphine
- and then aspirin
- so a smaller amount of heroin is needed to
reduce the same pain
Some drugs vary naturally in potency
- percentage of THC ranges from 1% to 10%