This document discusses screening models for evaluating anti-asthmatic, COPD, and anti-allergic drugs. It describes various in vitro and in vivo models used to test these drugs. The in vitro models discussed include histamine receptor assays, Cultex technique, and WST assays. The in vivo models described are the Konzett-Rossler method using guinea pigs, arachidonic acid/PAF-induced respiratory dysfunction in guinea pigs, anaphylactic microshock models in guinea pigs and rabbits, serotonin aerosol-induced asphyxia in guinea pigs, and bronchial perfusion of isolated lungs. The document provides details on the procedures and principles of each screening model.

1. Screening Models of Anti-
Asthmatic Drugs, Drugs for
COPD and Anti- Allergics
Presented by Ananya Upadhyay
Department of Pharmacology

2. What Is Asthma
Introduction : - Asthma is characterised by hyper responsiveness of
tracheobronchial smooth muscle to a variety of stimuli ,resulting in narrowing of air tubes ,often
accompanied by increased secretion of mucosal edema and mucus plugging .
Symptoms :- wheezing, Cough, running nose.
Types of Asthma :-
 Extrinsic Asthma :- It is mostly episodic ,less prone to status asthmaticus.
 Intrinsic Asthma :- it tends to br perennial ,status asthmaticus is more common

3. Drugs For Cough
Drug For Cough
Pharyngeal Demulcents Expectorants (Mucokinetics) AntiTussives(Cough Centre
Suppressant)
Adjuvant Anti Tussives
Lozenges
Syrups
Glycerine
Liquorice
Secretion Enhancer
Pot.Citrate
Pot.Iodiate
Tolu Balsam
Vaska
Mucolytics
Bromohexine
Ambroxol
Acetylcysteine
Carbocisteine
Opiods
Codeine
Ethylmorphine
Pholocodine
Nonopioids
Noscapine
Dextromethorphan
Chlophedianol
Antihistaminic
Chlorpheniramine
Diphenhydramine
Promrthazine
Bronchodilators
Salbutamol
Terbutaline

4. Drugs for Asthma
Asthma
Montelukash Sod.Cromoglycate
Zafirlukash Ketotifen
Corticosteroids
Anti IgE
Antibody
Mast cell
Stabilizer
Leukotriene
Antagonist
Bronchodilators
Systemic Inhalational
Omalizumab
B2 sympathomimetics Methylxanthines Anticholinergic
Hydrocortisone
Prednisolone
Other Glucocorticoids
Beclometasone
Dipropionate
Budesonide
Fluticasone
Propionate
Flunisolide
Ciclesonide
Salbutamol
Terbutaline
Bambuterol
Salmeterol
Theophylline
Aminophylline
Choline
Hydroxyethyl
Ipratropium Br.
Tiotropium Br.

5. What are Anti-Asthmatic Drugs?
 Anti-Asthmatic drugs are medicines that treat or prevent Asthma attacks.
 “Drugs for Asthma” refers to drugs that help open up the airways when they
become narrowed due to disease.
 Other drugs may be used on people with asthma and COPD, such as antibiotics
for infection, but they are not used to directly “open up” airways.

6. In-Vitro
 Histamine Receptor Assay
 Cultex Technique
 WST assay
 Spasmolytic activity in Guinea pig lungs
 Vascular & Airway responses to isolated lung

7. Histamine Receptor Assay
 Animal Used – Guinea Pig brain plasma (Male, 300-600g)
 Aim – To measure inhibitory activity of test compound on binding of 3H pyrilamine
(H1 antagonist)
 Total binding
 Non specific binding
 Specific binding (Total binding – Non specific binding)
 % inhibition of 3H pyrilamine binding (100-specific binding)

8. Procedure
Brain is homogenised in ice
cold Tris solution
Centrifuge for 10 minutes
Discard Supernatant
Resuspend pellets in buffer
& centrifuge again
Resuspend pellet in buffer
(1g/5ml)
Freeze alliquets of 1ml at -
70oc
Take 50μ 3H pyrilamine, 50μ
test drug, 100μ membrane
suspension in shaking bath
(25oC)
Incubate for 30 mins in Tris
HCL buffer
11 concentrations of 3H
pyrilamine saturation

9. CULTEX Technique
 New experimental method for cultivation & exposure of cells of respiratory tract
to air borne pollutants at air/liquid interface
 Enhanced efficiency of in-vitro studies
 Principles – Direct exposure of bronchial epithelial cells to complex mixtures
 Aim – To study factors influencing susceptibility of human bronchial epithelial

10. Procedure
Bronchial epithelial cells
washed with PBS
Incubate with test drug
for 24 hours
Cells exposed to clean air
(different concentrations of
smoke for 1 hr (Cell exposure
unit)

11. In-Vivo
 Konzett Rossler method ( Bronchospasmolytic activity in anesthetized guniea pig)
 Arachidonic acid/PAF induced respiratory vascular dysfunction.
 Anaphylactic micro shock
 Serotonin aerosol induced asphyxia
 Bronchial perfusion of isolated lung

12. Konzett- Rossler method
 The method is based on registration of air volume changes of a living animal in a closed system consisting
of the respiration pump, of the trachea and the bronchi as well as of a reservoir permitting measurement of
volume or pressure of excess air.
 Bronchospasm decreases the volume of inspired air and increases the volume of excess air. Thus, the degree
of bronchospasm can be quantified by recording the volume of excess air.
Procedure
Animal: guinea pig
Sex: m/f
Weight: 250-500g

13. Anesthetized with
i.p. urethane
Trachea cannulated
by two way cannula
Animal artificially
respired using
starling pump
Excess air not taken
up by lungs
Internal jugular vein
cannulated
Carotid artery
cannulated to
measure BP

14. Arachidonic acid/PAF induced respiratory &
vascular dysfunction
 Animal used – Guinea pig (Male, 300-600g)
 Anaesthetic used – Pentobarbitone sodium 60mg/kg i.p.
 Principle – Thromboxane caused Bronchoconstriction & Thrombocytopenia
Prostacyclin SBP & DBP
 Aim – To study & compare
 % inhibition or increase of bronchospasm
 BP reduction (measure magnitude & duration)
 Thrombocytopenia & haematocrit

15. Procedure
 Trachea – Artificial respiration (70-75 strokes/min)
 Jugular Vein – Test Drug
 Carotid Artery – Blood withdrawal & transducer attached for BP measurement
Record Bp & changes in airflow
Animal given multiple intravenous injections of arachidonic acid till 2 bronchospasms of
equal intensity are obtained
Test drug administered intravenously
Repeat spasmogen injections

16. Anaphylactic Microshock
 Animals used
 Guinea pig (200-300g) sensitized with s.c. injection of egg albumin
 Rabbit (2000-3000g) sensitized with 2% histamine aerosol
 Ova transgenic mouse model (mouse sensitized with ova i.p – Gold Standard Model
 Aim – Measure degree of protection (p) = [1 – (C/T)] * 100
Where C = control animals, T = treated animals
(c ≤ 40 secs ≥ 165 secs are excluded)

17. Procedure
(After 3 weeks)
Animals exposed to
5% aerosol of albumin
in exposure chamber
Remove as soon as
they become dyspneic
Measure pre-
convulsion time
If no sign of shock
seen after 6 mins, then
animal is regarded as
protected
After control exposure,
animal treated with
test drug
4 - 7 days
Control exposure

18. Serotonin Aerosol Induced Asphyxia
 Animal used – Guinea pig (200-300g)
 Principle – Serotonin causes bronchoconstriction -> Asphyxia & Death
 Aim – To evaluate % protection = (1-T1/T2) * 100
Where T1 = mean of control pre-convulsion time 2 days before & 2 days after
administration of drug
T2 = Pre-convulsion time with administration of drug

19. Procedure
Animal placed in anaesthetic box
& given 2% serotonin aerosol
Progressive signs of difficulty in
breathing & convulsions observed
Animal is taken out and placed in
fresh air
Test drug given within 1 min with
infusion pump & alternatively by
oral/s.c
Pre-convulsion time noted
Compare & Calculate % protection

20. Bronchial perfusion of isolated Lung
 The method consist in perfusing fluid down the trachea through the bronchi ,and
allowing it to escape from the alveoli through scratches in the surface of the lungs.
 Bronchoconstriction result in a reduced rate of flow ,bronchodilalation is indicated
by an increased flow.

21. Procedure
 Animal :- Guinea pigs
 Weight :- 200g
 Method :-
Sacrificed by head blow
trachea ,cut at upper end &
removed with lung trachea
attached to cannula of
perfusion apparatus
One lung perfused other
tied off lower part of lower
lobe cut off rest lung
surface scratched deeply
Perfusion fluid in
percentage of anhydrous
salt. PH 8
Histamine HCL is added in a
concentration of 1:2500 as
soon as perfusion starts &
flow is adjusted to obtain a
constant progressive increase
in pressure.
Trachea attached to cannula of
perfusion apparatus pump at
constant rate into Manometric tube
connected with perfused organ
bronchoconstriction result in heat
of coumn of fluid in manometer.
Temp 37’C lung enclosed
in glass cylinder.
Drug are injected near
cannula when perfusion
pressure reaches a level of
500-600 ml of water
Volume injected is always
0.1ml

22. REFRENCES
 Drug discovery and Evaluation : Pharmacological assays by H Gerhard Vogal.
 Preclinical model of asthma and Copd (Stevenson and Belvisi)
 Screening methods in pharmacology : - by Robert Turner

23. Thank you