This document describes an experiment to study the antipyretic (fever-reducing) effects of paracetamol and ketoprofen in rats with yeast-induced fever. Rats were injected with Brewer's yeast to cause pyrexia (fever). They were then divided into groups that received either a vehicle, paracetamol, or ketoprofen. Rectal temperatures were measured before and after yeast injection, and at regular intervals after drug administration, using a telethermometer. Drugs that reduce the fever by inhibiting prostaglandin synthesis in the hypothalamus are considered to have antipyretic activity. The experiment aimed to evaluate this property of paracetamol and ketoprofen

1. Expt No 5 Pharmacology I Practicals I Sem M.Pharm –Pharmacology, PESCP, PESU Page 1
Expt No-5 Date-10-9-2019
Antipyretic activity by yeast induced pyrexia in rats.
Aim- To study the antipyretic activity of paracetamol and ketoprofen in Brewer’s yeast
induced pyrexia in rats using telethermometer.
Theory- Fever (pyrexia) is common medical sign, characterized by increased body
temperature above the normal range of normal range of 36-37oC (98-100F). Pyrexia is caused
as a secondary impact of infection. Normally in infection the damaged tissue initiates the
enhanced formation of pro-inflammatory mediators like interleukin β, α, and TNF-α which
increase the synthesis of prostaglandin E2 (PGE2) in the hypothalamus region. This stimulates
the hypothalamus to elevate the body temperature. Drugs having anti-inflammatory activity
generally possess antipyretic activity (e.g) non-steroidal anti-inflammatory drugs (NSAIDs).
In general, non-steroidal anti-inflammatory drugs produce their antipyretic action through
inhibition of prostaglandin synthetase within the hypothalamus.
Telethermometer- It is ideal for continuous monitoring of temperature in laboratory animals
for study and research in antipyretic study and pyrogen testing. The required numbers of
sensor probes at different sites are connected to this instrument. The power switch is put on.
Select any particular probe by means of channel selector, and read temperature on the digital
display.
Procedure- Induction of pyrexia in rats-
Two rats were fasted overnight with water ad libitum before the experiments. Pyrexia was
induced by subcutaneous injecting 20% w/v Brewer’s yeast suspension (10ml//kg bw sc) into
the animal dorsum region. Nineteen hours after the injection, the rectal temperature of each
rat was measured using a thermometer. Only rats that showed an increase in temperature at
least 1oC were used for the experiments. 20% w/v Brewer’s yeast suspension is prepared by
using 2% w/v gum Acacia in normal saline.
Rats were divided into three groups of six animals each. Vehicle was treated to the first group
and the standard paracetamol (100mg/kg bw po) and aspirin administered to the second and
third group respectively. (Normal temperature measured before the administration of 20%
w/v Brewer’s yeast suspension (10ml/kg bw sc), again 19h after the administration of
Brewer’s yeast suspension rectal body temperature was measured using telethermometer).

2. Expt No 5 Pharmacology I Practicals I Sem M.Pharm –Pharmacology, PESCP, PESU Page 2
Group I (Normal group) Vehicle-2% w/v gum Acacia in normal saline. Dose -2ml/kg bw
SN M BW
in
gm
Vehicle
in ml
Brewer’
s yeast
ml (sc
route)
Normal
temp oC
Temp after
pyrexia
oC
Rectal temp after treatment of vehicle
oC
1h 2h 3h 4h
1 H 180 0.36 1.8 36 39
2 B
3 HB
4 TB
5 TT
6 UM
Group II (Paracetamol – 100mg/kg bw po) Paracetamol stock solution- 100mg/ml
SN M BW
in
gm
Paracetamol Brewer
’s yeast
ml (sc
route)
Norma
l temp
oC
Temp after
pyrexia oC
Rectal temp after treatment of vehicle oC
mg ml 1h 2h 3h 4h
1 H 200 20 0.2
2 B
3 HB
4 TB
5 TT
6 UM
Group II (Ketoprofen – 9 mg/kg bw po) Ketoprofen stock solution- 2 mg/ml
SN M BW
in
gm
Ketoprofen Brewer
’s yeast
ml (sc
route)
Norma
l temp
oC
Temp after
pyrexia oC
Rectal temp after treatment of vehicle oC
mg ml 1h 2h 3h 4h
1 H 200 20 0.2
2 B
3 HB
4 TB
5 TT
6 UM

3. Expt No 5 Pharmacology I Practicals I Sem M.Pharm –Pharmacology, PESCP, PESU Page 3