Urine Carbamate Determination Compared with Plasma Pseudocholinesterase for Diagnosis of Insecticides Poisoning

Carbamate insecticides act similarly to the organophosphates in that they inhibit acetyl cholinesterase enzyme (AChE) at nerve synapses and neuromuscular junctions. This inhibition is reversible with spontaneous hydrolysis occurring usually within several hours [1] thus, the inhibition of blood AChE is frequently not evident at the laboratory [2]. There are two main pharmacokinetic characteristics that distinguish carbamates from organic phosphorus compounds. First, carbamate insecticides do not easily cross into the central nervous system [3]. CNS effects of carbamates are thus limited. Second, the carbamate-cholinesterase bond does not “age” as in organic phosphorus compound poisoning. In Egypt, poisoning by carbamates is increasing in frequency. Diagnosis is frequently missed when the case is admitted after considerable delay with an almost normalized pseudo-cholinesterase and a normal true AChE on presentation. In 2011, the poison control center of Ain Shams University received and treated 259 carbamate poisoning cases [4]. In other hospitals and health care centers, records underestimate outbreaks of carbamates toxic exposure attributing them to bacterial food poisoning. Most of these outbreaks are due to premature crop harvesting. According to agricultural pesticides committee in Egypt the recommended Volume 2 Issue 3 2016