Mutant alleles at the BCHE locus are responsible for suxamethonium sensitivity. Homozygous persons sustain prolonged apnea after administration of the muscle relaxant suxamethonium in connection with surgical anesthesia. The activity of pseudocholinesterase in the serum is low and its substrate behavior is atypical. Butyrylcholinesterase is believed to play a role in the body's ability to metabolize the drug cocaine. In 2008, an experimental new drug was discovered for the potential treatment of cocaine abuse and overdose based on the BChE structure. It was shown to remove cocaine from the body 2000 times as fast as the natural form of BChE. Studies in rats have shown that the drug prevented convulsions and death when administered cocaine overdoses.