Niclosamide 98% TC Clonitralid Hight Effect Niclosamide Olamine CAS
Common name niclosamide (BSI, E-ISO, (m) F-ISO, BAN, Germany (for
IUPAC name 2',5-dichloro-4'-nitrosalicylanilide
Chemical Abstracts name
CAS RN [50-65-7] Development codes Bayer 25 648; Bayer 73; SR 73
Common name niclosamide-olamine (BSI, E-ISO, (m) F-ISO, BAN);
clonitralid (Germany, for public health use)
CAS RN [1420-04-8] Development codes SR73
Mol. wt. 327.1 M.f. C13H8Cl2N2O4 Form Almost colourless crystals.
M.p. 230 V.p. <1 mPa (20) KOW logP = 1 (pH 9.6) Solubility In water 1.6 (pH 6.4), 110 (pH
9.1) (both in mg/l, 20). Soluble in common organic solvents such as ethanol and diethyl
ether. Stability Hydrolysed in aqueous solution, DT50 (20) c. 7 d (pH 6.9), 18.8 d (pH 13.3). Stable to heat. Decomposes
under u.v. irradiation. Hydrolysed by concentrated acid or alkali.
Mol. wt. 388.2 M.f. C15H15Cl2N3O5 Form Yellow, crystalline solid.
M.p. Decomposes at 208 V.p. <<1 mPa (20) Solubility In water 0.1 g/l (20). In n-hexane, toluene <0.1, dichloromethane 0.015, isopropanol
0.25 (all in g/l, 20).
History Molluscicidal properties described by R. Gnert & E. Schraufstter (Proc. Int. Conf. Trop. Med. Malar., 1958, 2,5) and development
discussed by R. Gnert et al. (Z. Naturforsch., Teil B, 1961, 16,95). The olamine
salt introduced as a molluscicide by Bayer AG. Patents DE 1126374;
US 3079297; US 3113067 Manufacturers Bayer CropScience
Mode of action Molluscicide with respiratory and stomach action.
Uses Control of golden apple snail in rice. Control of
schistosomiasis and fascioliasis in man by killing fresh-water
snails which act as intermediate hosts. Also used for veterinary
control of tapeworm infestations. Formulation types EC.
Compatibility Incompatible with acidic materials. Selected
products: 'Bayluscide' (EC250) (Bayer CropScience) Formulation
Selected products: 'Bayluscide' (WP70) (Bayer CropScience);
'Trithin N' (Trithin)
Product analysis by redox titration (WHO Specifications Pesticides
Used in Public Health, p. 309). Residues in water measured by
colorimetry (R. Strufe, Pflanzenschutz-Nachr. (Engl. Ed.), 1962,
15, 42) or by titration (details from Bayer CropScience).
Oral Acute oral LD50 for rats ?000 mg/kg. Skin and eye Acute
percutaneous LD50 for rats >1000 mg/kg (EC250). Strong eye
irritant; skin reacts after repeated and long-lasting exposure
(rabbits). Inhalation LC50 for rats (1 h) 20 mg/l air. NOEL (2 y)
for male rats 2000, female rats 8000, mice 200 mg/kg diet; (1 y)
for dogs 100 mg/kg b.w. ADI 3 mg/kg b.w. (proposed) Other No
relevant mutagenic or embryotoxic effect. Toxicity class WHO (a.i.)
U; EPA (formulation) II
Oral Acute oral LD50 for rats >5000 mg tech./kg. Skin and eye
Acute percutaneous LD50 for rats >2000 mg (as 70% WP)/kg.
Inhalation LC50 (4 ?1 h) 3630-8224 mg/m3 air (as 70% WP).
Birds LD50 for mallard ducks >500 mg/kg. Fish LC50 (96 h) for
golden orfe 0.1 mg/l. Daphnia LC50 (48 h) 0.2 mg/l. Bees No
significant mortality effects.
Animals Following oral administration, 14C-niclosamide was absorbed
and metabolised in the rat. The major metabolite in the urine was
the reduced compound 2',5-dichloro-4'-aminosalicylanilide
([10558-45-9]); several labile conjugates were also detected. The
major constituent in the faeces was unchanged niclosamide, although
considerable amounts of 2',5-dichloro-4'-aminosalicylanilide were
also present; parent compound is present not only because of
non-absorption, but also because of release from the biliary
conjugate by b-glucuronidase of the intestinal microflora (L. A.
Griffiths & V. Facchini, "The major metabolite of niclosamide:
Identification by mass spectrometry" in Recent Developments in Mass
Spectrometry in Biochemistry and Medicine, 2, 121-126 (1979)).
Another study indicates that niclosamide is very poorly absorbed
after dermal application. Radioactivity in the urine and faeces
after application of 14C-niclosamide accounted for <2% and 10%
of the labelled compound applied to pig and rat skin, respectively;
c. 20% was recovered from the area of application (P. Brennan et
al., "Dermal absorption of niclosamide in rats and minipigs" in
Biopharmaceutics & Drug Disposition, Vol. 12, 547-556). Studies
in fish with niclosamide and its 2-aminoethanol salt, indicate that
niclosamide is rapidly excreted, as the glucuronide conjugate, and
that there is little biomagnification; see D. P. Schultz & P.
D. Harman, J. Agric. Food Chem., 26, 1226-1230 (1978); J. L. Allen
et al., "Excretion of the Lampricide Bayer 73 by Rainbow Trout",
Special Technical Publication, Philadelphia, 667, 52-61 (1979); and
M. S. M. Marzouk, "Laboruntersuchungen an Karpfener Rkstde von Bayluscid und dessen Einwirkung auf das Karpfenblut", PhD
Thesis, Univ. Munich, Germany (1981). Soil/Environment There was a
rapid decline in niclosamide residues in paddy water; degradation
followed pseudo-first order kinetics, DT50 0.3 d. At harvest,
niclosamide residues were below the detection limit of 0.03 mg/kg
in rice leaves, stalk and grain, indicating that the use of
niclosamide as a molluscicide in rice production does not lead to
persistent residues in the rice paddy ecosystem (S. M. F. Calumpang
et al., Bull. Environ. Contam. Toxicol., 55, 494-501 (1995)). An
aqueous solution of 14C-niclosamide was 95% degraded after 14 d
exposure to long-wavelength u.v. light. No degradation occurred
within 56 days either in buffered solution (pH 5.0, 6.9 and 8.7) or
in pond water (initial pH 7.8) (D. P. Schultz & P. D. Harman,
U.S. Fish and Wildlife Service: Investigations in Fish Control, 83,