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African Journal of Biomedical Research
Ibadan Biomedical Communications Group
ISSN: 1119-5096
Vol. 9, Num. 3, 2006, pp. 219-223
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African Journal of Biomedical Research, Vol. 9, No. 3, Sept, 2006, pp. 219-223
Full Length Research Article
Toxic Effects of
Non-Steroidal Anti-Inflammatory Agents in Rats
1*Abatan, M. O,
Lateef I. and 2Taiwo V.O.
1Department of
Veterinary Physiology & Pharmacology
2Department of Veterinary
Pathology, Faculty
of Veterinary Medicine, University of Ibadan, Ibadan, Ibadan,
Nigeria
*Address for
Correspondence:
Received: February, 2005
Accepted:November,
2005
Published: September,
2006
Code Number: md06035
ABSTRACT
The toxicosis of some
non-steroidal anti-inflammatory drugs, piroxicam, indomethacin, phenylbutazone,
and aspirin, which occasionally are locally used in Nigeria as rodenticides
have been evaluated in rats using changes in the serum biochemical and
haematological parameters as indices of toxicity. In the study, no clinical
symptoms were observed in all the treatment groups except in the group of
animals exposed to indomethacin which showed decreased feed intake,
sluggishness, diarrhoea and some mortality were also recorded in the group. On
the serum biochemical parameters, indomethacin and piroxicam caused increases
in the level of total bilirubin and decreases blood urea nitrogen. Aspirin,
indomethacin, and phenylbutazone produced increases in serum aspartate
aminotransferase and this increase is significant (P<0.05) with the group
treated with indomethacin compared to the control group. Indomethacin also
caused significant (P<0.05) increase in the level of serum alanine
aminotransferase. None of the treatment groups produced significant changes in
haematological parameters except that indomethacin produced significant
increase (P<0.05) in the total white blood cell count. Histological studies
revealed that indomethacin also caused mild periportal hepatic necrosis and
kupffer cell proliferation. This study therefore shows that some non steroidal
anti-inflammatory drugs may have adverse effects in rats. Indomethacin has the
greater toxic effect on rodents and this may suggest why it is marketed in
Nigeria as a rodenticide.
Keywords:
NSAID, toxicity, histopathology,
rat
INTRODUCTION
Non
steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen,
naproxen, and indomethacin are extensively used as analgesics and
anti-inflammatory agents and produce their therapeutic effects through the
inhibition of prostaglandin synthesis (Gilman et al, 1985; Klaassen, 2001).
Aspirin and other NSAIDs block the formation of colon cancer in experimental
animals, and there is epidemiological evidence that chronic NSAID usage
decreases the incidence of colorectal cancer in humans (Gupta and DuBois,
1998).
The
toxicity of some compounds can be directly related to their biliary excretion.
For example, indomethacin can cause intestinal lesions. The sensitivity of
various species to this toxic response is directly related to the amount of
indomethacin excreted into bile. The formation of intestinal lesions can be
abolished by bile duct ligation (Duggan et al., 1975). Often elimination of a
compound occurs by different routes in different species, as shown in the case
of indomethacin in the dog and the rhesus monkey. Dogs excrete most of a dose
in feces, whereas monkeys excrete the majority of a dose in urine. Both species
excrete greater proportion of a dose in bile as conjugates. These hydrophilic
indomethacin derivatives will not be reabsorbed unless they are hydrolyzed by
intestinal bacteria to the reabsorbable parent compound, or to phase I
metabolites. It appears that indomethacin undergoes enterohepatic circulation
with repeated conjugation in the liver and deconjugation in the small
intestine, with a gradual loss of conjugates into the large intestine. Limited
reabsorption of indomethacin is not surprising because more than 99.7 percent
of indomethacin is ionized in the large intestine which has a small surface
area (compared to the small intestine) (Klaassen, 2001)
Drug-induced
aplastic anaemia may represent either a predictable or idiosyncratic reaction
to a xenobiotic. This life threatening disorder is characterized by peripheral
blood pancytopenia, reticulocytopenia, and bone marrow hypoplasia (Young and
Maciejewski, 1997; Young, 1999). Indomethacin belongs to the group of
xenobiotics associated with aplastic anaemia. Furthermore at least three
different types of nephrotoxicity have been associated with NSAID
administration (Bach, 1997; Tarloff, 1997; Whelton and Watson, 1998). These
include acute renal failure which occur within hours of a large dose of a
NSAID; analgesic nephropathy which occurs from chronic consumption of NSAID
(Elseviers and De Broe, 1998) and interstitial nephritis which is characterized
by a diffuse interstitial edema with infiltration of inflammatory cells
(Whelton and Waston, 1998).
It
has being a local practice to use the NSAIDs most especially indomethacin as a
rodenticide which from personal observation is effective. The study was
therefore carried out to verify the pathogenesis of NSAIDs which could be
poisonous in therapeutic doses in rodents.
MATERIALS
AND METHOD
Experimental
Animals
White
albino rats of both sexes weighing between 200-250 gms were used for the
experiment. They were separated into groups of four consisting of six animals
per group, and maintained on rat cubes (Ladokun Feeds Nig. Ltd) and allowed
free access to water ad libitum
Experimental
technique
Drugs
used included indomethacin(Globa Pharmaceuticals, GMBH, Yantai, China), at
5mg/kg; piroxicam (Rajat Pharmaceuhem Ltd, India) at 15mg/kg; aspirin ( R &
C Pharmaceutical Ltd, South Africa) at 20mg/kg; and phenylbutazone (Vardnman
Export, India) at 10 mg/kg. All the drugs were dissolved in distilled water
before administration by dose to each animal in the group orally using a
stomach cannula for fourteen days. The animals were observed in their cages for
clinical symptoms daily. At the end of the experimental period the animals were
anaesthetized using diethyl ether and blood obtained by cardiac puncture for
haematological and serum biochemical analysis.
Determination
of biochemical and haematological parameters
Serum
was separated from clotted blood obtained by cardiac puncture. Total red blood
cell (RBC) and white blood cell (WBC) counts were made by the haemocytometer
method (Jain 1986), haemoglobin concentration(Hb) by the cyanmethemoglobin
method, packed cell volume (PCV) by capillary tube method. The differential WBC
counts were made by finding the percentage average of the different types of
cells counted in ten fields from Giemsa stained slides (Reagan, Sauders, and
DeNicola, 1998).
Serum
enzymes alkaline phosphatase (ALP), aspartate aminotransferase (AST) and
alanine aminotransferase (ALT) were determined by procedures of Sigma
diagnostics, blood urea nitrogen(BUN) by method of
Crocker (1967), total protein as done by Gornall, Bardawill and David (1947),
serum bilirubin by method of Michealsson (1961) as modified by Sigma
Diagnostics (1985).
Preparation of Histopathological slides
Organs such as the liver, thyroid, lungs, adrenal, and
kidney were isolated into saline formalin, and then subjected to histological
procedures and preparation of tissue slides as described by Cook (1973).
Statistical Analysis
Values are expressed as Mean ± standard
error of mean. Significant differences between values are determined using the
Students t test. Differences exist at P<0.05 (Steel, and Torie, (1986)
RESULTS
Clinical
Effects of Non Steroidal Anti-inflammatory Drugs in rats
No
clinical symptoms were observed with the administration of aspirin and
phenylbutazone. Animals administered with indomethacin showed reduced feed
intake, sluggishness, unthrifty appearance, diarrhea with some mortalities. The
only symptoms seen in the group given piroxicam was sluggishness.
Effect
of the NSAIDS on the serum biochemical parameters of rats
Indomethacin
and piroxicam produced slight increase in the level of total bilirubin but
decrease in the blood urea nitrogen levels. All the NSAIDS used produced
significant increases (P<0.05) in the level of alkaline phosphatase except
the increase by piroxicam which was not significant(P>0.05). Aspirin,
indomethacin, and phenylbutazone caused increases in the level of serum enzyme
AST.
Table
1. Serum
biochemical parameters of administered with some NSAIDs
PARAMETERS |
Control |
Aspirin |
Indomethacin |
Phenylbutazone |
Piroxicam |
Total bilirubin mg/dl |
0.25±0.4 |
0.25±1.2 |
0.3±0.5 |
0.23±0.2 |
0.35±0.04 |
Total protein g/dl |
6.5±0.1 |
6.7±0.04 |
6.7±0.1 |
6.3±0.02 |
6.4±0.04 |
Albumin g/dl |
3.7±0.4 |
3.7±0.04 |
3.3±0.07 |
3.3±0.08 |
3.5±0.07 |
Urea mg/dl |
21.0±0.7 |
*25.0±2.1 |
*18.5±4.6 |
*24.5±3.3 |
22.5±0.35 |
ALP U/L |
140.0±0.7 |
*169.5±13.7 |
*176.0±16,9 |
*156.0±15.7 |
144.0±8.5 |
AST U/L |
27.0±0.7 |
30.0±1.4 |
*33.0±2.1 |
30.0±4.4 |
24.0±4.2 |
ALT U/L |
18.5±0.4 |
15.0±3.6 |
*23.5±1.1 |
19.5±2.7 |
16.5±4.6 |
*
indicates values are significantly different from their corresponding controls
Table
2. Haematological
parameters of rats exposed to NSAIDs
|
PCV % |
RBC |
WBC |
Hb |
L |
N |
M |
E |
Control |
44.2
±
1.5 |
6.8
±
0.1 |
10400
±
318.2 |
13.1
±
0.7 |
51.5
±
0.4 |
47.5
±
1.1 |
1.0
±
0.7 |
|
Aspirin |
44.5
±
0.4 |
6.9
±
0.3 |
9050
±
636.4 |
14.1
±
1.3 |
49.5
±
0.5 |
47.0
±
3,2 |
0.5
±
1.5 |
3.0
±
0.6 |
Indomethacin |
46.5
±
0.4 |
7.2
±
0.3 |
*15171
±
724.8 |
14.2
±
0.04 |
51.5
±
0.4 |
46.0
±
4.1 |
1.5
±
0.4 |
1.5
±
0.5 |
Phenylbutazone |
46.3
±
0.7 |
7.1
±
0.2 |
6700
±
410.8 |
14.5
±
0.2 |
50.5
±
0.6 |
47.5
±
0.6 |
0.75
±
0.4 |
1.25
±
0.7 |
Piroxicam |
40.5
±
3.9 |
6.8
±
0.8 |
9300
±
352.6 |
13.0
±
1.4 |
49.0
±
1.4 |
48.5
±
0.4 |
1.0
±
0.5 |
2.5
±
0.4 |
- indicates
values are significantly different from their corresponding controls
This
increase is significant (P<0.05) with the group given indomethacin.
Furthermore indomethacin also produced significant increases (P<0.05) in
levels of alanine aminotransferase. There were no significant
changes(P>0.05) in the levels of total protein and albumin in all the
treatment groups (Table 1)
Effect
of the NSAIDS hematological parameters of rats
No
significant hematological changes (P>0.05)were observed in all the treatment
groups except the group treated with indomethacin which showed
significantly(P<0.05) increased levels of total WBC (Table 2)
Histopathological
Changes in rats administered with the NSAIDS
Lungs
of rats given indomethacin showed large focus of hemorrhage into the
interstitium and alveoli with mild periportal hepatic necrosis and kupffer cell
proliferation
DISCUSSIONS
The
non steroidal anti-inflammatory drugs(NSAIDs) belong to the group of the most
abused drugs by virtue of combining the pharmacological actions of
anti-inflammatory and analgesia and because they can easily be bought over the
counter(Gilman et al, 1990).
This
study has shown that the NSAIDs when improperly used, could serve as a source
of harm to animals. This is because all the NSAIDs used produced significant
increase in the level of ALP. Also, aspirin, indomethacin and phenylbutazone
caused increase in AST. Increase in level of serum ALP has been associated with
bile duct damage (Bush, 1991; Duncan et al 1994; Klaassen, 2001). However this
damage may not be as serious with aspirin and phenylbutazone since the increase
in ALP is not associated with increase in total bilirubin which is also
secreted in the bile. Indomethacin and piroxicam produced significant
increases in the level of ALP and total serum bilirubin. This suggests that
indomethacin and piroxicam caused more severe damage to the liver. However
indomethacin caused greater damage because it also produced significant
increase in the level of serum enzyme ALT, and AST. Increases in the serum
levels of AST and ALT (especially ALT) are reported to be associated with liver
damage (Kaneko, 1985; Bush 1991).
The
fact that indomethacin caused greater damage to the animals is further
confirmed by the histopathologic lesions produced. Administration of
indomethacin caused periportal hepatic necrosis and kupffer cell proliferation.
These are all signs of acute hepatoxicity (Smith and Jones, 1986; Hodgson and
Levi, 1985; Klaassen, 2001), and may suggest that indomethacin is a
hepatotoxicant in rats and the effect on the liver may be one of the causes of
death in poisoned rats.
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