This document summarizes screening methods for evaluating the antipyretic (fever-reducing) effects of drugs in animal models. It describes using the Brewer's yeast suspension method to induce fever in rats and rabbits, and then testing potential antipyretic drugs. Key points: 1) Drugs are given to fevered animals and temperatures recorded at intervals to see if drugs lower elevated body temperatures compared to controls. 2) Studies summarized evaluated antipyretic effects of extracts from Bauhinia racemosa and Gracilaria corticata seaweed in rats. Both produced significant antipyretic activity. 3) The rabbit model uses bacterial lipopolysaccharides to induce fever and tests

1. SCREENING OF ANTIPYRETIC DRUGS:
• PRESENTED BY :SINDHOORA D
FIRST MPHARM
DEPT.OF.PHARMACOLOGY
SCP,MANGALORE
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2. SCREENING OF ANTIPYRETIC DRUGS
CONTENT:
• Introduction to antipyretic drugs
• Screening models
 Antipyretic activity in rabbits
 Antipyretic activity in rats
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3. The drugs which lowers the elevated body
temperature to the normal .
Drugs used are :
• Aspirin
• paracetamol
ANTIPYRETIC DRUGS:
3

4. Mechanism of action :
• Antipyretic drugs resets the thermostat
toward normal and rapidly lowers the body
temp of febrile patients by increasing heat
dissipation as a result of peripheral
vasodilation and sweating
• Inactivation of COX enzyme.
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5. Screening models :
• Brewer’s yeast suspension method
Antipyretic activity in rabbits
Antipyretic activity in rats
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6. Brewer’s yeast suspension method:
• Taken rats avg wt (150 -200 gm)
• Body temperature by rectal thermometer
• 15% brewer’s yeast+0.9% saline sol inject rat
subcutaneously &placed for 18 hr
• When body temperature rises test drug is
given
• Record the response at 30,60,120,180min
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7. Evaluation:
• A decrease of body temperature for at least
0.5°C for more than 30 min as compared with
the temperature value before administration of
the test compound is regarded as positive
effect.
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8. Antipyretic activity of Bauhnia
Racemosa Lam. in rat
• The plant Bauhinia racemosa Lam.
Belongs to the “Caesalpiniaceae” Family. It
is popularly known as “Apta” in Marathi,
“Kanchnal” in Hindi. Dhar et al, (1968)
reported the antipyretic activity in mice
from the hydro alcoholic extracts of
Bauhinia racemosa.
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9. • Thirty six healthy Wistar Albino rats of 200-
250gms were divided into six groups of six
animals each, with 50% sex ratio.
• The initial rectal temperature of each animal
was recorded by digital thermometer and its
hourly variation was noted for 3 and their
average was recorded
• The pyrexia was induced by injecting a
suspension of 15% of brewer’s yeast and 2%
gum acacia in normal saline sub-cutaneously
below the nape of neck in the volume of
1ml/100gm of animal weight. 9

10. • The aqueous extract was given orally to
group 1& 2 of 100,200mgkg
• The alcoholic extract was given orally to
group 3& 4 of 100,200mgkg
• The 5 group is given with paracetamol of
100,200mgkg
• Sixth group is given with saline sol of 0.5 ml
serve as negative control.
• Rectal temperature was recorded at 1,2&3
hour.
• The difference in temperature between 0 hour
and at the end of 3 hr it is compared
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11. • Aqueous and alcoholic extracts of
Bauhinia racemosa Lam. produced
significant antipyretic activity in rats,
which was induced by brewer’s yeast.
The temperature was brought back to
normal after 4 hrs of post administration of
extracts. The aqueous extract
@200mg/kg body weight and alcoholic
extract @100mg/kg and 200mg/kg body
weight was found to have significant effect
and was found significant at 5% level of
significance
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12. Group Temp of Apyretic rats Temp of Pyretic rats Average Temp After drug
administration
1Hr 2Hr 3Hr 1Hr 2Hr 3Hr
T1 98.8±0.210 98.2±0.502 98.51±0.422 101.48±0.465 101.81±0.360 101.86±0.212 101.86 ±0.280 101.91±0.267
T2
98.53±0.174 98.48±0.535 97.98±0.445 101.51±0.263 100.51±0.339 99.45 ±0.292 99.76±0.254** 99.33±0.130
T3
98.7±0.271 97.9±o.425 98.23±0.325 101.58±0.195 101.21±0.336 101.23±0.189 101.36±0.172 101.27±0.232
T4
97.9±0.403 98.85±0.291 98.43±0.382 101.48±0.215 101.23±0.413 101.1±0.304 100.86±0.284 101.06±0.334*
T5
98.57±0.354 98.3±0.276 98.78±0.310 101.46±0.212 100.53±0.283 100.78±0.265 100.27±0.257** 99.5±0.225
T6
98.56±0.389 98.43±0.399 98.11±0.228 101.75±0.105 101.01±0.153 100.28±0.318 100.28±0.228** 99.56±0.212
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13. Antipyretic activity of Gracilaria
Corticataj
• Gracilaria corticata J.Ag. is red seaweed
belonging to Rhodophyceae member shows
much attention in the present study for
antipyretic activity. Gracilaria corticata J.Ag.
were collected from Hare island, Thoothukudi in
the south east coast of Tamil Nadu.
• The shade dried samples were grounded to fine
powder & 3g powdered sample was packed in
Soxhlet apparatus and extracted with methanol
for 8 hrs.
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14. • The excess amount of methanol was evaporated
and fine methanol crude powder was prepared
and stored in the refrigerator for the antipyretic
activity.
• Swiss albino rats were weighing (150-240 gm)
and male albino rats (15-18 gm) were used. The
animals were housed in the departmental animal
house under standard conditions (26±2°C and
relative humidity 30-35%) in 12 hours light and
12 hours dark cycle respectively for 1 week
before the experiment.
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15. The experimental treatment was
carried out as;
• Group I: Control group animals Normal
saline 5ml/kg
• Group II: Animals were treated with
Paracetamol (10mg/kg)
• Group III: Animals were administered with
200mg/kg methanol extract
• Group IV: Animals were administered with
400mg/kg methanol extract
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16. Antipyretic activity:
• A suspension of Brewer’s yeast (15%) in saline (0.9%)
was prepared. Four groups each containing 6 rats of
either sex were taken. The animals were fevered by
injection of brewer’s yeast suspension (10mg/kg)
subcutaneously . The measurement was repeated after
30 minutes. The dose of the test compound and
standard drug was given orally.
• The rectal temperature was recorded again after 1, 2
and 4 hours. Paracetamol (10mg/kg) was selected as a
standard drug. The various methanol extracts were
dissolved in saline with the help of 2% w/v Gum
acacia.
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17. Results:
• Antipyretic activity of methanol crude extract of
Gracilaria corticata J.Ag. was studied by determining
the effect on yeast-induced pyrexia in albino rats.
• The result expressed that methanol extract of
different doses caused lowering of the body
temperature up to 4h following its administration.
• The effect of methanol extract on yeast-induced
pyrexia showed that the rectal temperature was
markedly elevated to 41.7°C, after 18h the
subcutaneous injection of yeast suspension decreased
to 40.7°C within 1h of 200mg/kg methanol extract of
Gracilaria corticata J.Ag. treatment followed by
39.6°C at 2h and further reduced to 38.2°C at 4h
showing a considerable decrease in compared to
paracetamol
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18. • 400mg/kg methanol extract also showed the
decreased in temperature from 41.4°C to
39.6°C after 1h of treating with the
administration of the methanol crude extract
of Gracilaria corticata J.Ag.
• When the time was increased up to 4hr,the
results were observed significant reduced
temperature to 37.2°C.
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19. • Both 200 and 400mg/kg marked antipyretic
activity detected were significantly different
than the controls (p<0.05).
• Generally, for all concentration of methanol
crude extract of Gracilaria corticata J.Ag.
showed marked antipyretic activities, hence,
400mg/kg methanol extract was highly effective
than 200mg/kg.
• This result revealed that the methanol extract of
Gracilaria corticata J.Ag. have detectable
antipyretic activity as compared with standard
paracetamol.
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20. Antipyretic activity in rabbits:
• Purpose and Rationale:
Lipopolysaccharides from Gram-negative
bacteria ,e.g. E.coli, induce fever in rabbits
after i.v injection.
Body weight of 150 g are used.
Intial temperature is noted down.
Fewered by injection of 10mlkg Brewers
yeast suspension by s.c .
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21. • The room temperature is kept at 22-24c̊.
• The animals are recieve the test and standard
drug by oral
• The rectal temperature are recorded in
30,60,120 and 180 min post dosing
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22. Evaluation :
• The difference between the actual values and
the starting values are registered for each
time interval.
• The maximum reduction in rectal temperature
in comparison to the control group is
calculated.
• Results are compared with effect of the
standard drug ,e.g. aminophenazone 100
mg/kg,
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23. References
• Drug Discovery and Evaluation
:Pharmacological Assays, Third completely
Revised Edition , by H.Gerhard Vogel
• Study of Antipyretic Activity of
Bauhinia racemosa lam in Rats , by
V.I.Borikar, C.R Jangde, Preety Philip,
D.S. Rekhe and S.K Atole. Department
of Veterinary Pharmacology and
Toxicology, Veterinary College,
M.A.F.S.U. Nagpur Maharashtra
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24. • Screening of antipyretic activity of
Garcilaria Corticataj. AG . ,by John Peter
Paul J.
Research department of botany ,
St.Xevir’s college,Palaikottai - Tamilnadu
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