Pseudocholinesterase deficiency

Pseudocholinesterase deficiency, also called butyrylcholinesterase deficiency, is a condition that is characterized by an increased sensitivity to certain substances, including the medications succinylcholine and mivacurium. These medications may be given during general anesthesia. General anesthesia is typically used during major surgeries and causes a brief period of unconsciousness. Succinylcholine and mivacurium relax the muscles used for movement (skeletal muscles), including the muscles involved in breathing. 

Succinylcholine and mivacurium are typically broken down (metabolized) by the body within a few minutes of being administered. However, people with pseudocholinesterase deficiency do not metabolize these medications as quickly, so they remain active longer than usual. As a result, people with pseudocholinesterase deficiency may not be able to move or breathe on their own for a few hours after succinylcholine and mivacurium are administered. Affected individuals must be supported with a machine to help them breathe (mechanical ventilation) until the medications are cleared from the body.

People with pseudocholinesterase deficiency may also have an increased sensitivity to other substances, including cocaine and the local anesthetic procaine. Local anesthetics are used to numb a small area of the body. Affected individuals may also be more sensitive to specific agricultural pesticides. 

Because affected individuals typically have no other signs or symptoms, pseudocholinesterase deficiency is usually not discovered until a person has an abnormal reaction to one of these substances.