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Administrative data

Description of key information

For the oral route a subchronic study in rats (using chlorhexidine digluconate solution in water to achieve the following nominal dose levels (as chlorhexidine base) through administration in drinking water: 50, 100 and 200 mg/kg bw/day). Additionally chronic oral studies have been performed with rats (using 20% chlorhexidine digluconate solution in water to achieve the following nominal dose levels (as chlorhexidine base) through administration in drinking water: 0, 5, 25 and 50 mg/kg bw/day; additional group was dosed with chlorhexidine at 50 mg/kg bw/day and para-chloranilin at 0,125 mg/kg bw/day) and dogs (using 20% chlorhexidine digluconate solution in water to achieve the following nominal dose levels (as chlorhexidine base) through administration in capsules: 0, 0.5, 5 and 40/25 mg/kg bw/d; highest dose was reduced after 28 w). 
For dermal exposure data from a 13-week study with chlorhexidine diacetate in rabbits as well as from a 13-week bathing study in neonatal rhesus monkeys are taken into consideration. The dose levels expressed as chlorhexidine base administered in this 13-week dermal toxicity study in rabbits were: 0, 250, 500 or 1000 mg/kg bw/d, whereas in the 13-week bathing study in neonatal Rhesus monkeys an 8% (w/v as Chlorhexidine digluconate) was adminstered.
Due to the physico-chemical properties of the substance exposure via inhalation is unlikely. Therefore, testing for inhalation toxicity is scientifically not justified.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Dose descriptor:
LOAEL
5 mg/kg bw/day
Study duration:
chronic
Species:
rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Dose descriptor:
NOAEL
250 mg/kg bw/day
Study duration:
subchronic
Species:
rabbit

Additional information

The results of toxicity studies with repeated administration of chlorhexidine digluconate in animals are summarised in the following Table.

Oral

A subchronic study has been conducted in rats and chronic studies have been conducted with rats and dogs.

Repeated dose toxicity of chlorhexidine digluconate (nominal dose levels in table expressed as chlorhexidine base)

Route

Duration of study

Species
strain
sex (m/f)
no/group

Nominal Dose levels (mg/kg · d)
frequency of application

Results

LO(A)EL

mg/kg · d*

NO(A)EL

mg/kg · d*

Feeding (capsules)

1 year

Dog
Beagle
male/
female
5/5

0.5
5
40/25
Daily

Hepatic centrilobular fibrosis

5

0.5

Drinking water

2 years

Rat
Wistar
male/female
112/112

5
25
50
50 + 0.125 pCA
a

Continuously

Reactive histiocytosis of mesenteric lymph nodes, reversible

5

not derived

Drinking water

3 months

Rat
not reported
m/f
6/6

50
100
200
Continuously

Presence of giant cells in abdominal lymph nodes

48.5

not derived

A: pCA: para-chloroaniline
*Expressed as dose of chlorhexidine base.

In a chronic toxicity study comparable to OECD guideline 452 with rats, the only consistent treatment-related finding in rats was a histiocytosis of the mesenteric lymph nodes. There were no other histological effects on any organ or effects on haematology, clinical chemistry or urine analysis. The histiocytosis was reversible after cessation of exposure. There was no evidence of related damage to the intestinal mucosa or the submucosa which could be related to the histiocytosis in the mesenteric lymph node. The histiocytosis in treated rats is considered to be a reactive change and a local reaction which is restricted to and results from the presence of foreign bodies in the node.

Similar observations were described in an older subchronic study with rats. The only treatment-related change besides a reduced weight gain at the highest dose was the presence of giant cells in abdominal lymph nodes.

In contrast, dogs developed hepatic lesions after one year oral administration of chlorhexidine digluconate in capsules. At terminal sacrifice, there was an increase in macroscopic observations for the liver with white capsular striations and/or dark areas. Histopathology revealed treatment-related hepatic changes after 6 and after 12 months and after the 2-month recovery period. At the highest dose, changes were characterised by focal degeneration, necrosis and loss of hepatocytes and, in a few dogs, extensive irregular areas of necrosis and loss of hepatocytes over several liver lobules. Changes associated with these findings were focal mononuclear infiltrations, haemorrhages, bile duct hyperplasia, fibrosis, haemosiderosis, and acute inflammatory cell infiltrates. In animals of the mid dose group, treatment-related changes were characterised by centrilobular fibrosis. No such effects were observed at the lowest dose.

 

Dermal

Data are available from a non-guideline but well-conducted and described scientific study with neonatal Rhesus monkeys. The animals were washed daily for a three month period with 5 ml of an antimicrobial skin cleanser containing 8 %chlorhexidine digluconate, corresponding to a dermal daily applied dose of approx. 225 mg chlorhexidine base/500-600 cm² skin area (0.67 -0.8 mg/cm²). This value represents an upper bound estimate since the animals were washed with water afterwards. Although chlorhexidine is strongly bound to the skin, this is likely to have washed off some chlorhexidine digluconate.There were no treatment-related changes in haematology and serum chemistry and in organ histology compared to controls washed with water or cleanser free of chlorhexidine digluconate. Chlorhexidine was bound to the skin and, in some animals, very low concentrations could be detected in blood and organs, and also in faeces, but not in bile. It is likely that the presence of chlorhexidine in the body may have at least partially arisen through oral uptake from grooming.

A 13-week dermal toxicity study was performed with chlorhexidine diacetate in rabbits. Animals were exposed to the moistened test substance under occlusive conditions. The treatment caused minimal dermal irritation with erythema, oedema, desquamation and fissuring. In females, the activity of the aspartate aminotransferase and of the alanine aminotransferase were increased at >= 500 mg/kg/d. The incidences of hepatocellular degeneration/necrosis were 0, 1 (not significantly different from control), 5, and 7 with increasing dose. In male the incidence was not statistically significant different from the control. The liver necrosis was graded as “minimal” in all animals. 250 mg/kg/d was considered as a NOEL for systemic effects.


Repeated dose toxicity: via oral route - systemic effects (target organ) cardiovascular / hematological: lymph nodes

Repeated dose toxicity: dermal - systemic effects (target organ) digestive: liver

Justification for classification or non-classification