Transcript Epinephrine

Experiment no. 2
FACTORS AFFECTING
DRUG ACTION
Influence of Chemical Structure
C3
A. Macasaet, P. Macatangay, G. Madulara, C. Magno, P.
Magsino, M. Malig, F. Mallari, S. Mamba, Jr., A. Manguba, Jr.,
M. Mangubat, S. Mansukhani, A. Manzana, C. Manzano, C.
Maranion, K. Marasigan, E. Marayag, P. Marcelo, K. Marcial,
E. Martin, M. Matematico, E. Matias, M. Maulion
General Objective
To determine the effects of
Epinephrine, Dobutamine, and
Terbutaline on heart rate and
amplitude based on their chemical
structure
2
Specific Objectives
• To measure the rate and amplitude
of baseline contractions of the
turtle’s heart
• To measure the rate and amplitude
of contractions caused by each drug
• To evaluate the results of each drug
with p value set at 0.05 using oneway ANOVA
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Animals
8 Turtles per drug
Materials
•Kymograph set-up
•Dissecting set
•Kymograph paper
•Paste
•Cotton thread
•Surgical gloves
•Tuberculin syringe
•Tyrode solution
•Heart hook
• Surgical thread
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Drugs
Epinephrine
(1:1000 ampule)
Dobutamine
(250mg/20mL)
Terbutaline
2.5mg/mL
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Methodology and Rationale
1. Apex of turtle’s heart was attached
to a kymograph set up
2. Baseline rate and amplitude were
obtained for 1 minute.
3. Drugs were directly instilled to the
heart muscle (1 mL in 1 minute).
4. Rate and amplitude of contraction
were recorded for three minutes
from instillation
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5. Tyrode or NSS solution was
used to wash the heart after
each drug administration
6. Results were recorded and
subjected to statistical analysis.
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Drugs
Epinephrine
• sympathomimetic, direct-acting
• a potent vasoconstrictor and
cardiac stimulant
• acts on alpha-1, alpha-2, beta-1,
and beta-2 receptors
• increase peripheral resistance via
alpha-1 vasoconstriction; beta-1
response is increased cardiac rate
and output
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Dobutamine
• synthetic catecholamine
• Beta agonist
– beta-1 receptors >>> beta-2 receptors
• lesser effect on alpha 1 receptors
• primary activity: stimulation of the betaadrenoceptors of the heart
–  contractility,  cardiac output
• Used often in patients with heart failure
– ( cardiac output  ventricular filling pressure)
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Terbutaline
• Beta-2 selective
• used as a fast-acting
bronchodilator
– often used as a shortterm asthma treatment
• tocolytic to delay
premature labour.
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Rationale of Drugs
• The structure of a sympathomimetic
drug influences:
– relative affinity for alpha and beta
adrenergic receptors
– intrinsic activity
– pharmacokinetic properties
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Structure-Activity Relationship
Increase of the size
of alkyl substituents
on the amino group
:
increase beta receptor
activity
–  activity is further increased if there is
an isopropyl substitution at the amino
nitrogen.
– 2 selective agents: typically have a
large amino substituent group.
– as size of the substituent , activity at 
receptors .
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DOBUTAMINE
EPINEPHRINE
TERBUTALINE
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• Catecholamines have maximal  and 
activity.
– replacing the -OH groups at the 3 and 4
positions will reduce such activity
– In terms of degree of reduction in potency at 3
& 4 positions:
3 position substitution > 4 position
• Absence of the -OH groups
– increases bioavailability & duration of action
because the drug is no longer a substrate for
COMT metabolism.
• Replacing the -OH groups
– also makes the resulting drug more widely
distributed in the body
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DOBUTAMINE
EPINEPHRINE
TERBUTALINE
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• substitution at the  carbon
– prevents metabolism of a drug by MAO.
– prolongs action of non-catecholamines.
• substitution at the  carbon is typical
for direct-acting agonists.
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DOBUTAMINE
EPINEPHRINE
TERBUTALINE
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Expected Results
Rate:
Epinephrine>Dobutamine>Terbutaline
Amplitude:
Epinephrine>Dobutamine>Terbutaline
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HYPOTHESIS
Ho: There are no significant differences
among the effects of drugs
Ha: There are significant differences
among the effects of drugs
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Amplitude
(% Difference)
GROUPS EPINEPHRINE
DOBUTAMINE
TERBUTALINE
A1
-20.0
-36.36
14.29
A2
-125.0
-30.0
0
B1
7.69
-50.0
37.5
B2
0.0
5.88
0
C1
-40.0
55.55
-14.29
C2
0
7.69
0
D1
-37.5
66.6
-25.0
D2
21.05
8.33
0
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ANOVA: Single Factor
SUMMARY
Groups
Count
Sum
Average
Variance
Column 1
8
-193.76
-24.22
2120.089
Column 2
8
-43.17
-5.39625
1123.22
Column 3
8
12.5
1.5625
345.7324
ANOVA
Source of
Variation
SS
Between Groups
2846.654
Within Groups
Total
df
MS
F
P-value
F crit
2
1423.327
1.189727
0.323997
3.4668
25123.29
21
1196.347
27969.94
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• Since P value is not < 0.05, failed to
reject null hypothesis.
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RATE
(% Difference)
GROUPS
EPINEPHRINE
DOBUTAMINE
TERBUTALINE
15.22
6.0
6.25
-8.11
-2.22
3.85
-4.08
-4.76
0
6.12
2.70
-11.90
A1
0.0
A2
-11.63
B1
8.16
B2
0.0
C1
8.33
C2
-11.63
D1
2.08
2.44
4.76
6.12
D2
-11.63
4.76
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ANOVA: Single Factor
SUMMARY
Groups
Count
Sum
Average
Variance
Column 1
8
-32.69
-4.08625
87.4814
Column 2
8
35.06
4.3825
41.50894
Column 3
8
-10.53
-1.31625
33.41308
df
MS
F
P-value
F crit
2.755321
0.086575
3.4668
ANOVA
Source of
Variation
SS
Between Groups
298.3157
2
149.1578
Within Groups
1136.824
21
54.13447
1435.14
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Total
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• Since P value is not < 0.05, failed to
reject null hypothesis.
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SOURCES OF ERROR
• Bleeding
• Trauma
• Error on kymograph set-up
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CONCLUSION
•
Epinephrine, which is a direct acting, mixed alpha and beta
adrenergic agonist, has the greatest effect in increasing the
rate and amplitude of contractions, followed by Dobutamine, a
selective beta-1 agonist, and Terbutaline, a beta-2 selective
drug, has the least effect.
•
The chemical structures of Epinephrine, Dobutamine, and
Terbutaline indicates their selectivity and effect on heart rate
and amplitude of contraction.
•
The rate and amplitude of baseline contractions of the turtle’s
heart was measured using the kymograph.
•
Using One-Way ANOVA, the resulting P values of Amplitude
and Rate are not less than 0.05, therefore, there are no
significant differences among the effects of drugs.
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Thank you!
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Heart Rate
A
B
C
D
Baseline
Epinephrine
Baseline
Dobutamine
Baseline
Terbutaline
36
36
46
39
45
46
43
48
50
47
52
50
49
45
48
45
49
51
50
50
37
40
40
42
36
33
41
40
37
37
43
48
42
40
49
46
42
48
49
46
37
36
43
48
42
40
42
47
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Amplitude
A
B
C
D
Baseline
Epinephrine
Baseline
Dobutamine
Baseline
Terbutaline
10
12
11
15
14
12
4
9
10
13
4
4
13
12
6
9
8
5
5
5
8.5
8
9
9
10
14
9
4
7
8
6
6
13
14
4
4
8
11
9
8
8
10
19
15
12
11
20
20
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Recommendation
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