The first step in the metabolism of carbamates is hydrolysis to carbamic acid, which decomposes to carbon dioxide (CO2) and the corresponding amine. The mechanism of hydrolysis is different for N -methyl and N -dimethyl derivatives. The N -methyl carbamates pass through an isocyanate intermediate, whereas in the hydrolysis of N - dimethylcarbamates, an addition product with a hydroxyl ion is formed yielding the alcohol and N -dimethyl substituted acid. The rate of hydrolysis by esterases is faster in mammals than in plants and insects. Apart from hydrolysis, oxidation also takes place including: hydroxylation of the aromatic ring, O -dealkylation, N -methyl hydroxylation, N -dealkylation, oxidation of aliphatic side chains, and sulfoxidation to the corresponding sulfone. Oxidation is associated with the mixed-function oxidase (MFO) enzymes. Conjugation leads to the formation of O - and N -glucuronides, sulfates, and mercapturic acid derivatives in mammals. Glycosides and phosphates are conjugation products more common in plants. /Carbamate Pesticides/
Artificial respiration (via a tracheal tube) should be started at the first sign of respiratory failure and maintained for as long as necessary. Cautious administration of fluids is advised as well as general supportive and symptomatic pharmacological treatment and absolute rest. /Carbamate pesticides/
When dermal exposure occurs, decontamination procedures include removal of contaminated clothes and washing of the skin with alkaline soap or with a sodium bicarbonate solution. Particular care should be taken in the cleaning of the skin area where venupuncture is performed. Blood might be contaminated with carbamates and therefore inaccurate measures of ChE inhibition might result. Extensive eye irrigation with water or saline should also be performed. In the case of ingestion, vomiting can be induced, if the patient is conscious, by the administration of ipecacuanha syrup... followed by... water. However, this treatment is contraindicated in the case of pesticides dissolved in hydrocarbon solvents. Gastric lavage (with the addition of bicarbonate solution or activated charcoal) can also be performed, particularly in unconscious patients, taking care to prevent aspiration of fluids into the lungs (i.e., only after a tracheal tube has been put in place). The volumes of the fluids introduced in the stomach should be recorded and samples of gastric lavage frozen and stored for subsequent chemical analysis. If the formulation of the pesticide involved is available, it should also be stored for further analysis (i.e., detection of toxicologically relevant impurities). A purge to remove the ingested compound can be administered. /Carbamate pesticides/
The clinical approach to carbamate toxicity is similar to that for organophosphate poisoning; the major exception is that pralidoxime usually is not recommended. /Carbamates/
Stabilization: Assess the adequacy of the airway and ventilation and use oxygen, suction, intubation, artificial ventilation, intravenous lines, and cardiac monitors as needed. /Carbamates/
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
在哺乳动物中，口服给药后，药物以其原形和代谢物形式在尿液中排出。
In mammals, following oral administration, eliminated in the urine both in the unchanged form and as metabolites.
Little information is available on the distribution of carbamates in the various organs and tissues in mammals following exposure by inhalation or the oral route. The organs in which residues have been reported are the liver, kidneys, brain, fat, and muscle.The half-life in the rat is of the order of 3-8 hr. It seems that the excretion of carbamates via urine is also rapid in man, and that the metabolic pathways in man are the same as those in the rat. /Carbamate Pesticides/
