Download Depressants - CDNIS Moodle

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Medicines and Drugs 4
Depressants (SL and HL)
1
The Drug Development Process
D.4.1
Describe the effects of depressants.
Distinguish between effects at low, moderate and high doses.
D.4.2
Discuss the social and physiological effects of the use and abuse of ethanol.
D.4.3
Describe and explain the techniques used for the detection of ethanol in
the breath, the blood and urine.
Include the breathalyzer, chromotagraphic tests of blood or urine, and the intoximeter.
D.4.4
Describe the synergistic effects of ethanol with other drugs.
D.4.5
Identify other commonly used depressants and describe their structures.
Only diazepam (Valium), nitrazepam (Mogadon) and fluoxetine hydrochloride (Prozac) are required.
2
Common Depressant Drugs
3
Mode of Action of Depressants
Depressants act on the
central nervous system.
i.e. brain + spinal cord
Depressants “depress” or slow down brain activity.
tranquilizers
sedative
hypnotic
Slowing down brain activity may also affect other organs.
muscle action
respiratory function
4
Mode of Action of Depressants
utube.com/
ugPM83c
Signals pass from neuron
to neuron in the brain.
http://www.youtube.com/watch?v=90cj4NX87Yk
Depressants often block receptors on
neurons, preventing the normal binding of
neurotransmitters.
Transmission of signals from neuron
to neuron stops.
X
X
X
Effect depends on the brain
pathway.
5
Dose Dependent Effect of Depressants
very high dose coma / death
high dose
hypnotic
respiratory depression
sleep inducing
slurred speech
staggered gait
moderate dose
sedative
low dose
tranquilizer
greater soothing and relief
of anxiety
mild relief of anxiety
muscle relaxant
6
Ethanol
C2H5OH
the “alcohol” in beer,
wine, hard liquor
produced through the fermentation of various crops
polar molecule (due to OH group)
small molecule → able to pass through cell membranes
7
Ethanol - Physiological Effects (Short Term)
low dose
sense of well being
loss of inhibitions
depressant action on brain
centres related to tension
and anxiety
impaired concentration
memory loss
high dose
staggered gait
impaired motor function
risk taking behaviour
very high dose
coma / death
depressant action on brain
centres related to
co-ordination, balance, pain
sensation, judgement
depressant action on brain
centres related to
respiratory control
8
Ethanol - Physiological Effects (Long Term)
cardiovascular
disease
brain damage
strokes
cirrhosis
long term effects
dependence
high blood
pressure
stomach
cancer
fetal alcohol
syndrome
9
Ethanol - Social Effects
use
abuse
celebrations and ceremonies
alcoholism
loss of productivity
motor vehicle accidents
illness → health care costs
others →
10
Ethanol - Synergistic Effects
1+1>2
synergy = combination of two drugs taken at the same
time is more powerful than either drug taken alone
(usually considered with respect to the negative side effects)
alcohol + aspirin → increased stomach
bleeding + ulcers
alcohol + other depressants →
heavy sedation
possibly coma
11
Methods Used to Measure Ethanol
Blood Alcohol Concentration (BAC)
BAC = mass of ethanol in grams per 100 mL of solution
legal limits = 0.08 g in 100 mL
What mass of ethanol is present in
a 50 cm3 blood sample with a BAC of 0.11?
0.11 g
3
mass ethanol =
x 50 cm
3
100 cm
= 0.055 g
12
Methods Used to Measure Ethanol
1. The Breathalyser Test
portable device for roadside testing
→ measures alcohol vapour in breath
chemical reaction =
oxidation of alcohol by potassium dichromate
ethanol + acidified dichromate → ethanoic acid + chromium (III)
C2H5OH + H2O → CH3COOH + 4 H+ 4 e–
x3
Cr2O72– + 14 H+ + 6 e– → 2 Cr3+ + 7 H2O
x2
3 C2H5OH + 2 Cr2O72– + 16H+ → 3 CH3COOH + 11H2O
13
Methods Used to Measure Ethanol
1.The Breathalyser Test
redox reaction
→ generates a small voltage
→ converted to a BAC reading
often inaccurate and unreliable
results not admissible in court
disposable single use tests
Cr2O72–
Cr3+
14
Methods Used to Measure Ethanol
2. The Intoximeter
measures alcohol level in breath
→ more reliable
→ confirms roadside test results
based on infra-red spectroscopy
→ molecules absorb IR radiation
→ molecules start to vibrate
→ bonds stretch
→ different bonds absorb different wavelengths of IR radiation
15
Methods Used to Measure Ethanol
2. The Intoximeter
C-H bonds
in ethanol can
be analyzed on
this profile to
determine
ethanol conc’n
O-H bonds
not used in the
analysis
(O-H bonds also
present in water
vapour)
IR spectrum
profile = type of substance
peak heights = concentration
16
Methods Used to Measure Ethanol
3. Gas Liquid Chromatography
can analyse alcohol levels in breath, blood and urine
(separates molecules based on mass and solubility in column matrix)
retention time
area under peaks = concentration
17
Other Depressants
benzodiazepams
suppress brain activity in regions that control emotion
used as tranquilizers, anti-anxiety drugs and sleep inducers
diazepam
similarities:
2 benzene rings
nitrazepam
heterocyclic ring
amide
(diazepine)
differences:
halogen vs nitro group
3º amide vs 2º amide
properties:
nonpolar ∴ ...
18
Other Depressants
SSRI Inhibitors
SSRI = selective serotonin reuptake inhibitor
serotonin → neurotransmitter used in brain pathways for “well-being”
→ low levels associated with depression
→ SSRI keep serotonin levels high
http://www.youtube.com/watch?v=sc-4zhqViQ4
SSRI ≠ not truly a depressant → does not depress CNS activity
Prozac - antidepressant
19