Committee For Veterinary Medicinal Products
Committee For Veterinary Medicinal Products
Committee For Veterinary Medicinal Products
EMEA/MRL/695/99-FINAL
November 1999
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6. Repeated dose toxicity studies were provided in rats and dogs. In rats, equivalent doses of 0, 50,
150 and 500 mg/kg bw of acetylsalicylic acid were given daily as acetylsalicylic acid DL-lysine
and 500 mg/kg bw as sodium acetylsalicylate. The highest dose induced severe clinical
abnormalities and mortality. No clinical signs were observed at 150 mg/kg bw. Congestion,
petechiae, haemorrhages, and punctiform lesions were observed in the stomach at 150 and
500 mg/kg bw. Necropsy examination revealed a dose related hepatomegaly, with no histological
expression. Kidney weights were increased in males at all dose levels. A dose related decrease in
serum globulins was recorded. This effect was still significant at the lowest dose tested
(50 mg/kg bw) in females.
In dogs, acetylsalicylic acid DL-lysine was administered at doses of 0, 50, 150, 250 and 500 mg
acetylsalicylic acid equivalents/kg bw/day for 3 months and sodium acetylsalicylate was
administered at doses of 0, 250 and 500 mg/kg bw/day. The highest dose induced rapid mortality
and all animals died within 2 to 7 days post treatment initiation. Doses of 150 and 250 mg/kg
induced vomiting and mortality. Vomiting were still observed at the dose of 50 mg/kg but at a
lower frequency. In this group (n=6), one dog presented gastric striae and two dogs presented
focal atrophy of the mucosa with dedifferenciation of the epithelial lining and glandular
epithelium. A slight decrease in the heart rate in all of the treated animals was recorded.
From these repeated dose toxicity studies, no NOEL could be established.
7. Tolerance studies in target animal species were not submitted.
8. Embryotoxicity and foetotoxicity studies in dogs (days 15 to 21, days 23 to 30), mice (treatment
period not stated) and rats (days 6 to 15) with doses of 500 to 1200 mg/kg bw orally resulted in a
high incidence of stillborns in dogs and of resorption in mice and rats. In the rabbit, inseminated
does given 7 doses (150 mg/kg bw) of acetylsalicylic acid prior to implantation showed reduced
fertility and abnormal blastocysts. Doses of 40 mg/kg bw given to pregnant Rhesus monkeys
(days 25 to term) did not induce anomalies. No fertility studies in accordance with Volume VI of
the Rules Governing Medicinal Products in the European Community were provided.
9. In an oral teratology study, rats were treated on days 6 to 15 of pregnancy with doses of 30, 90
and 180 mg sodium salicylate/kg bw. A significant dose-related reduction in foetal weight and
significant increases in delayed ossification of the limbs and vertebrae were observed at 90 and
180 mg/kg bw. In the 90 mg/kg bw group, one foetus had anophthalmia and another had
generalised oedema together with a malformed tail. 30% of the foetuses in the 180 mg/kg bw
group were malformed; the predominant malformation was craniorachischisis affecting 22.7% of
the foetuses in this group. The dose of 30 mg/kg bw was without foetotoxicity or teratological
effects. In rat in vitro studies (embryo mid-brain cells) level lower than 50 µg/ml plasma did not
provoke teratogenic effects.
In rat in vitro studies (whole embryos) with levels of 100 µg salicylic acid/ml plasma did not
cause teratogenic effects.
In dogs no teratogenic nor embryotoxic effects were seen with doses of 100 mg acetylsalicylic
acid/kg bw; by contrast maternotoxicity, increase in the number of resorption and malformations
(including cleft palate, micrognathia, anasarca, cardiovascular malformations and tail
malformations) were observed with doses of 400 mg/kg bw.
Although teratogenic effects were observed in rats and dogs studies, an oral dose of 30 mg
sodium salicylate/kg bw could be accepted as a NOEL for teratogenicity.
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10. Negative results were obtained in 5 independent bacterial gene mutation assays in both the
presence and absence of metabolic activation with sodium salicylate. In vitro DNA-repair tests in
bacteria and in primary rat hepatocytes also gave negative results. Acetylsalicylic acid did not
induce recessive lethal mutations in Drosophila melanogaster. Inconsistent results were obtained
in in vitro metaphase analyses: positive results were obtained in fibroblast and lymphocyte
cultures but negative results were obtained in V79 cells both with and without metabolic
activation. Negative results were also obtained in a cell transformation assay in mouse embryo
cells. Positive results were reported in an in vivo metaphase analysis in rat bone marrow. In vivo
chromosomal aberration assays in rat embryos and in vivo micronucleus tests in bone marrow
from rats and mice also gave negative results. No evidence of chromosomal damage was found in
the lymphocytes of human volunteers administered oral doses of 2.4 g per person per day of
acetylsalicylic acid for 1 month. The Committee concluded that the balance of the evidence
indicated that acetylsalicylic acid was not genotoxic.
11. No carcinogenicity studies on acetylsalicylic acid were provided. However, its lack of
genotoxicity suggests that it would not be active as an initiator of neoplasms.
Some studies have been performed on the potential of acetylsalicylic acid to promote tumours
initiated by other agents. The results of a study of the promotional activity of chemicals on
tumours of the rat glandular stomach showed a lower incidence of hyperplasia and tumours of the
glandular stomach and duodenal tumors in animals given acetylsalicylic acid (1% in diet for 32
weeks) than in control animals.
Similarly 0.05 and 1% acetylsalicylic acid in the diet for 58 weeks did not increase the incidence
of liver tumours in rats pre-treated with a potent initiator of liver cancer. In contrast, 0.5%
acetylsalicylate in the diet for 12 weeks after initiation with a potent inducer of bladder cancer
caused an increased incidence of bladder carcinoma.
12. In humans, the reported adverse effects include nausea, vomiting and dyspepsia and more rarely,
blood dyscrasias such as thrombocytopenia, aplastic anaemia and agranulocytosis. Acetylsalicylic
acid has been associated with haemolytic anaemia in individuals with glucose-6P-dehydrogenase
deficiency. Even doses of 300 mg per person (5 mg/kg bw) daily or less carry a risk of peptic
ulcer bleeding. Hypersensitivity reactions have also been reported. A dose-dependent tinnitus and
hearing loss has been reported with serum acetylsalicylic acid concentrations higher than
110 µg/ml. Reversible hepatotoxicity has been associated with serum concentrations higher than
150 µg/ml. Reye’s syndrome (acute encephalopathy and hepatic fatty degeneration, occurring
mostly in children) has been associated with ingestion of acetylsalicylic acid in children suffering
from viral infection such as varicella or influenza. For this reason the substance is no longer
indicated in children, except in cases of juvenile rheumatoid arthritis, in some countries. The
occurrence and severity of the disease are linked to the salicylate concentration, which shows a
dose-related effect. Data collected in the USA showed that patient with Reye's syndrome were
found to have received greater average daily and maximum daily doses of sodium acetylsalicylate
and greater doses of sodium acetylsalicylate for the first 4 days preceeding illness (median
25.1 mg/kg bw; 33.0 mg/kg bw; and 65.4 mg/kg bw, respectively) than did controls (median
14.5 mg/kg bw; 19.0 mg/kg bw; and 27.0 mg/kg bw, respectively). The incidence of Reye’s
syndrome in USA declined sharply after the association of Reye’s syndrome with sodium
acetylsalicylate was reported. In countries where sodium acetylsalicylate and salicylates are
widely used in animals, no increase of incidence has been reported. Reye's syndrome seems
therefore to be linked with ingestion of high doses of sodium acetylsalicylate or other salicylates
and should be regarded as a dose-dependent phenomenon which is very unlikely to be observed
after ingestion of minute doses as residues in food.
In humans, the widespread use of acetylsalicylic acid for treatment of hypertension during
pregnancy at a dose of 150 to 325 mg/person has not been associated with teratogenic effects in
the offspring. Acetylsalicylic acid is contraindicated at term because of its inhibition effect on
platelet function and its uterine relaxant properties.
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The results of epidemological studies are inconsistent with regard to the cancer risk to humans.
There was some evidence of an increased risk of renal cancer in people on long-term therapy with
acetylsalicylic acid, but a large cohort study of more than 620 000 persons showed only a
decreased incidence of colon cancer. There is no information to suggest that the concentrations of
acetylsalicylic acid likely to occur as food residues will cause any tumour promotion.
13. In absence of a NOEL from the repeated dose toxicity studies no toxicological ADI could be
established for acetylsalicylic acid. A pharmacological ADI of 0.0083 mg/kg bw (i.e.
0.5 mg/person) can be established on the LOEL of 0.167 mg/kg bw/day observed in humans
(based on effects on bleeding time and thromboxane B2-production), using a safety factor of 20.
This factor resulted from the standard safety factor of 10, when human data form the basis of the
ADI, multiplied by a factor 2, which was considered necessary since a LOEL rather than a NOEL
was used as basis to derive the ADI.
14. No radiolabelled residue depletion studies in the target species were provided.
15. In 12 pigs (body weight 23 kg), acetylsalicylic acid in a premix was administered orally at the
dose of 50 mg/kg bw/day for 10 consecutive days as two daily administrations. Four animals
were sacrificed 24 hours, 3 days and 7 days after the end of administration. Tissue were assayed
for acetylsalicylic acid and salicylic acid residues. Acetylsalicylic acid was converted to salicylic
acid and the results were expressed as total salicylic acid. The mean residue values at 24 hours
were 167 µg/kg in muscle, 387µg/kg in liver, 363 µg/kg in kidney and 816 µg/kg in skin and fat.
At 3 days, the values dropped below the limit of quantification in muscle. In the liver, the values
were 164 and 78 µg/kg in 2 animals and below the limit of quantification for 2 animals. The mean
value in kidney was 72 µg/kg in kidney. In skin and fat, the values were 200 and 156 µg/kg in
2 animals and below the limit of quantification in 2 other animals. At 7 days, the values were 58
and 210 µg/kg in 2 animals in muscle and below the limit of quantification in the 2 remaining
animals. In the liver, the values were 81 and 51 µg/kg in 2 animals and below the limit of
quantification in 2 other animals. In kidney the values ranged from 80 to 100 µg/kg and were
below the limit of quantification in one animal. In skin and fat, the values were 194 and
124 µg/kg in 2 animals and below the limit of quantification in 2 other animals. From these data,
the daily intake from pig edible tissues would be 160 µg at 24 hours, 25 µg at 3 days and 40 µg at
7 days.
Residue depletion studies following parenteral administration of acetylsalicylic acid DL-lysine
were not performed in pigs.
In 18 chickens, a water-soluble powder containing carbasalate calcium was administered orally in
drinking water at a dose equivalent to 50 mg of acetylsalicylic acid/kg bw/day for 5 consecutive
days. Animals were sacrified 24 hours, 3 days and 7 days after the end of administration. Tissue
samples were assayed for acetylsalicylic acid and salicylic acid residues. Acetylsalicylic acid was
converted to salicylic acid and the results were expressed as total salicylic acid. At 24 hours, the
values were below the limit of quantification in muscle (50 µg/kg), liver and kidney, whereas in
skin and fat the mean value was 206 µg/kg. At 3 days, the muscle residues were below the limit
of quantification in 2 animals and ranged from 83 to 614 µg/kg in 4 animals. In liver, the residue
values were 91 and 271 µg/kg in 2 animals and less than limit of quantification in 4 animals. In
kidney, residues were only detectable in one animal (399 µg/kg). In skin and fat, the values
ranged from 203 to 2468 µg/kg. At 7 days, residue in muscle, liver and kidney were only
detectable once in each tissue, whereas values ranged from 82 to 2444 µg/kg in skin and fat.
Taking into account the mean values recorded, the daily intake from chicken edible tissues would
be 18 µg at 24 hours, 175 µg at 3 days and 52 µg at 7 days.
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Twenty cattle aged 8.8 months on average were administered an intramuscular injection of
acetylsalicylic acid DL-lysine at the dose of 50 mg acetylsalicylic acid equivalents/kg bw/day, for
2 consecutive days as tw2o daily administrations. Four animals in each group were sacrificed 12,
24, 48, 96 and 240 hours after the last dose. Tissues were assayed for acetylsalicylic acid and
salicylicacid residues. Acetylsalicylic acid was converted to salicylicacid and the results were
expressed as total salicylic acid. Kidney was the target tissue. Total salicylic acid residues were
765 µg/kg at 12 hours in kidney and dropped to 186 µg/kg at 24 hours. Residues were still
detectable at 240 hours (132 µg/kg). In liver, residues were detectable in 2 animals at 12 hours
(76 and 217 µg/kg) and were close to the limit of quantification (50 µg/kg) or lower than the limit
of quantification at the other sampling times. In muscle and fat, the residues were lower than the
limit of quantification (100 and 50 µg/kg respectively) at each time sampling. At the injection
site, the mean residues were 659 µg/kg (n=4) at 12 hours and 452 µg/kg (n=3) at 24 hours. An
outlier value of 7506 µg/kg was recorded in the remaining animal. At 240 hours, salicylic acid
was still detectable in 2 animals (142 and 180 µg/kg). The daily intake from cattle tissues taking
into account mean values would be 53 µg and 15 µg at 12 and 24 hours respectively.
Residue depletion study following administration via oral route was not performed in cattle.
16. No residue depletion studies were performed in lactating cows.
17. No residue depletion studies in laying hens were performed.
18. An HPLC analytical method with spectrofluorimetric detection for the determination of residues
of acetylsalicylic acid and salicylic acid in tissues is available. Validation data were provided for
edible tissues in cattle, pigs and chickens. The limit of quantification was 50 µg/kg for all
tissues, excepted for cattle muscle (100 µg/kg). The method was described in the ISO 78/2
format. However no methods for the determination of residues in eggs and milk were provided.
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Conclusions and recommendation
Having considered that:
• a pharmacological ADI of 0.0083 mg/kg bw (i.e. 0.5 mg/person) has been established for
acetylsalicylic acid,
• the depletion of residues of acetylsalicylic acid, acetylsalicylic acid DL-lysine and
carbasalate calcium in cattle, pigs and chicken tissues is rapid,
• residues likely to be ingested by the consumer are below the ADI at all time points, the
maximum amounts being 11% from bovine tissues 12 hours after treatment, 33% of the ADI
from porcine tissues 24 hours after treatment, 36% from chicken tissues 3 days after
treatment,
• no information on residue depletion was available for bovine milk and chicken’s eggs;
the Committee for Veterinary Medicinal Products recommends the inclusion of acetylsalicylic
acid, sodium acetylsalicylate, acetylsalicylate DL-lysine and carbasalate calcium in Annex II of
Council Regulation (EEC) No 2377/90 in accordance with the following table:
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