screening methods

1. Presented by
D.Sukumar
M.Pharm 1styear
pharmacology
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2. Antianginals
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It is a most common type of heart disease.
It is symptom of coronary artery disease.
Angina pectoris is a severe,sudden,substernal chest
pain due to ischemia of the heart muscle.
Caused whenheart needs more oxygen then coronary
blood vessel

3. TYPES
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Three types
1)stable(classic angina)
2)unstable
3)Prinzmetal angina(varient)
 Stable: Attacks are provoked by
exercise,emotion,eating
 Unstable: occur during rest and sleeping
and are rare unpredictable
 Prinzmetal:Due to rapid increase in
duration and severity of attack

4. Treatment
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 ORGANIC NITRATES: Isosorbide dinitrate,
mononitrate
 B-blockers: propranalol,metapronol
 Calcium channel blockers :verapamil
 K+ channel openers:Nicoranidil

5. Models to screen anti anginal drugs
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IN VITRO MODELS
>Langendorff heart preparation
>Isolated rabbit aorta preparation
>Calcium antagonism in pitched rats
>Relaxation of bovine coronary arery
>Coronary artery ligation inisolated rat heart
Isolated heart- lung preaparation
Plastic casts technique in dogs

6. INVIVO MODELS
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Occulision of coronary artery
Microspheres-induced acute ischemia
Isoproterenol-induced myocardial necrosis
Stenosis-induced coronary thrombosis model
Electrical stimulation-induced coronary thrombosis
Myocardial-ischemic preconditioning model
Models of coronary flow measurement

7. PRINCIPLE
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 Heart is perfused in a retrograde direction from the
aorta either at const pressurewith oxygenated saline
solution

8. INVITROMODELS
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 Langendorff heart preparation:
 Guinea pigs(wt -300-500) are sacrified by stunning
 Heart is isolated by transabdominal incision &cut
carefully.Heart is cradled b/w fingers and lofted before
incising the aorta ,vena cava & pulmonary veins
 Immediately after incision heart is dipped in cold perfusion
solution (4*c)
 Aorta is located & cut & cannula is inserted in to it and heart
is per fused with oxygenated ringer’s solution.
 Heart is transferred to a double wall plexiglas perfusion
apparturs maintained at 37*c.
 Oxygenated ringers solution is perfuse at constant pressure of
40m hg.

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 Small steel hook with a strin is attached to the apex
of the heart.
 Contractile force is measured isometrically by a
force transducer & recorded on a polygraph
 Heart rate is measured through chronometer
coupled to the polygraph.
 Drugs r injected in to perfusion medium.
 Test drug->incresase in coronary blood flow.
 Method is used to testing coronary vasodilator drugs.
 Application is widely in pharmacology & physiology

11. CALCIUM CHANNEL BLOCKERS
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 Sprague-dawley rats(250-350)are anaesthesized ip with
methohexitone sodium(50mg/kg).
 Trachea is cannulated .
 Rats are pitched through one orbit and maintain artificial
respiration.
 Pithing rod is a stimulating electrode and continous electrical
stimulation producing a cardio-accelerator response.
 Jugular vein is cannulated for administration for
administration of drugs & b.p is recoded via carotid artery
using a pressure transducer.
 In the femoral region,an in different electrode is inserted sc.
 ca+2blockers & B-blockers are administrated which cases
tracycardia.

12. 3.ISOLATED RABBIT AORTA PREPARATION
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 Aortic rings are used to evaluate S.M relaxant in this metod . Addng
kcl, to the organ bath sightly modifies krebs bicarbonate buffer
induces contracn of aorta
 Over dose of pentobarbitol NA Rabbits r either sex weighing 3-4kg
 Heart is opened in bilateral incision
 Thorax is rapidly removed and kept in kreb’s bicarbonate solution
maintained 37*c
 Eight ring of 4-5mm width are obtained and each is mounted in 20
ml tissue bath containing kreb’s cycle.
 For every 2hrs kreb’s solution is frequently changed followed by
sterilizN period 1hr
 A tension ofof 1gm is maintained during 3times.
 concN is generated by additN of kcl.
 20times of after adding agonist thetest drug is added
 The % relaxation is reading is taken every 30min after addition of
test drug.
 30min time interval b/w additN of diff test drugs.

13. Invivo models
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 Isoproterenol-induced myocardial necrosis :
 Wister rats (150-200g) are pretreated with test
drugs orally or s.c for atleast a week.
 Isoproterenol(85mg/kg) is injected sc on 2
consecutive days.
 Mortality as well as symptoms are recorded in each
group & compared to grp injected with isoproterenol
only.
 After 48hrs of of 1st dose animals r sacrified.
 A
 Heart is removed & weighed & preserved for for
various biochemical parameters.

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 Before sacrificing the animal haemodynamic
parameters such as sistolic /diastolic b.p & h.r are
noted & connected to pressure transducer.
 Degree of histological changes can be graded as
follows
 grade 0: No change
 Grade 1:fecal areas of necrosis
 Grade 2:Fecal areas of necrosis & muscle fiber
fragmentation
 Grade 3:confluent areas of necrosis, edema,
inflammation
 Grade 4:massive areas of necrosis , edema,&
inflammation & mural thrombi

15. Myocardial-ischemic preconditioning model
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 Rabbits (3-4kg) are anesthesized with ketamine
(50mg/ml)/ xylazine .(10)at dose 0.06ml/kg
 Trachea cannulated and animal is set up for artificial
respiration
 Right femoral artery and vein are catheterised for
measuring hemodynamic parameters
 A4-0 suture is looped loosely around the marginal
branch of left coronary artery to facilitate coronary
occlusion
 Ischemic preconditioning is induced by tightening the
loop around the coronary artery for 5 min and then
loosening to reperfuse the myocardium for 10min prior
to a subsequent 30min occlusion

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 After 30min ischemia, ligation is released for 120min
of reperfusion
 Per to 30min of occlusion rabbits r selected to
receive ischemic preconditioning, no preconditioning
or preconditioning along with the administration of
test compound.
 Animals are sacrificed after reperfusion duration.
 Compared with controlled groups.
 Data is analysed by ANOVA using statistical software