Pseudocholinesterase deficiency
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Pseudocholinesterase deficiency is an inherited blood plasma enzyme abnormality in which the body's production of butyrylcholinesterase (BCHE; pseudocholinesterase) is impaired. People who have this abnormality may be sensitive to certain anesthetic drugs, including the muscle relaxants succinylcholine and mivacurium as well as other ester local anesthetics.[1]
Affected groups
Multiple studies done both in and outside India have shown an increased prevalence of pseudocholinesterase deficiency amongst the Arya Vysya community. A study performed in the Indian State of Tamil Nadu in Coimbatore, on 22 men and women from this community showed that 9 of them had pseudocholinesterase deficiency, which translates to a prevalence that is 4000-fold higher than that in European and American populations.[2]
Persian Jews
Pseudocholinesterase deficiency (anesthesia sensitivity) is an autosomal recessive condition common within the Persian and Iraqi Jewish populations. Approximately one in 10 Persian Jews are known to have a mutation in the gene causing this disorder and thus one in 100 couples will both carry the mutant gene and each of their children will have a 25% chance of having two mutant genes, and thus be affected with this disorder. This means that one out of 400 Persian Jews is affected with this condition.[3]
Effects
The effects are varied depending on the particular drug given. When anesthetists administer standard doses of these anesthetic drugs to a person with pseudocholinesterase deficiency, the patient experiences prolonged paralysis of the respiratory muscles, requiring an extended period of time during which the patient must be mechanically ventilated. Eventually the muscle-paralyzing effects of these drugs will wear off despite the deficiency of the pseudocholinesterase enzyme. If the patient is maintained on a mechanical respirator until normal breathing function returns, there is little risk of harm to the patient.
However, because it is rare in the general population, it is sometimes overlooked when a patient does not wake-up after surgery. If this happens, there are two major complications that can arise. First, the patient may lie awake and paralyzed, while medical providers try to determine the cause of the patient’s unresponsiveness. Second, the breathing tube may be removed before the patient is strong enough to breathe properly, potentially causing respiratory arrest.
This enzyme abnormality is a benign condition unless a person with pseudocholinesterase deficiency is exposed to the offending pharmacological agents.[4]
Complications
The main complication resulting from pseudocholinesterase deficiency is the possibility of respiratory failure secondary to succinylcholine or mivacurium-induced neuromuscular paralysis.
Individuals with pseudocholinesterase deficiency also may be at increased risk of toxic reactions, including sudden cardiac death, associated with recreational use of cocaine.
Prognosis
Prognosis for recovery following administration of succinylcholine is excellent when medical support includes close monitoring and respiratory support measures.
In nonmedical settings in which subjects with pseudocholinesterase deficiency are exposed to cocaine, sudden cardiac death can occur.
Patient Education
Patients with known pseudocholinesterase deficiency may wear a medic-alert bracelet that will notify healthcare workers of increased risk from administration of succinylcholine.
These patients also may notify others in their family who may be at risk for carrying one or more abnormal pseudocholinesterase gene alleles.
Drugs to avoid
Drugs containing Succinylcholine - e.g. Quelicin & Anectine
These drugs are commonly given as muscle relaxants prior to surgery. That means that victims of this deficiency cannot receive certain anesthetics.
A dose that would paralyze the average individual for 3 to 5 mins can paralyze the enzyme-deficient individual for up to 2 hours. The neuro-muscular paralysis can go on for up to 8 hours.
If this condition is recognized by the anesthesiologist early, then there is rarely a problem. Even if the patient is given succinylcholine, he can be kept intubated and sedated until the muscle relaxation resolves.[5]
Drugs containing Mivacurium - e.g. Mivacron
Mivacron is also a muscle relaxant that is used prior to inserting a tube for breathing.
Drugs containing Pilocarpine - e.g. Salagen
Salagen is used to treat dry mouth. As the name suggests, dry mouth is a medical condition that occurs when saliva production goes down. There are lots of different causes of dry mouth including side effect of various drugs.[5]
Drugs containing Butyrylcholine
Use of butyrylcholine is not common. It can be used to treat exposure to nerve agents, pesticides, toxins, etc.[5]
Drugs containing Huperzine A and Donepezil
These drugs are used to slow the progression of Alzheimer's disease.[5]
Drugs containing Propionylcholine and Acetylcholine[5]
Drugs containing Parathion
Parathion is used as an agricultural pesticide. Exposure to pesticides with Parathion should be avoided.[5]
This drug is injected before and during various surgical or dental procedures or labor and delivery. Procaine causes loss of feeling in the skin and surrounding tissues.[6]
Testing
This inherited condition can be diagnosed with a blood test. If the total cholinesterase activity in the patient's blood is low, this may suggest an atypical form of the enzyme is present, putting the patient at risk of sensitivity to suxamethonium and related drugs. Inhibition studies may also be performed to give more information about potential risk. In some cases, genetic studies may be carried out to help identify the form of the enzyme that is present.[7]
References
- ^ Maiorana, A; Roach Jr, RB (2003). "Heterozygous pseudocholinesterase deficiency: A case report and review of the literature". Journal of Oral and Maxillofacial Surgery. 61 (7): 845–7. doi:10.1016/S0278-2391(03)00163-0. PMID 12856264.
- ^ Manoharan, I; Wieseler, S; Layer, PG; Lockridge, O; Boopathy, R (2006). "Naturally occurring mutation Leu307Pro of human butyrylcholinesterase in the Vysya community of India". Pharmacogenetics and genomics. 16 (7): 461–8. doi:10.1097/01.fpc.0000197464.37211.77. PMID 16788378.
- ^ Cedars-Sinai Medical Genetics Institute. (2009). "Genetic Screening in the Persian Jewish Community". [1] Retrieved July 20, 2011.
- ^ Alexander, Daniel R. (2002). Pseudocholinesterase deficiency. Retrieved Mar. 13, 2007.
- ^ a b c d e f Li, B.; Duysen, E. G.; Carlson, M.; Lockridge, O. (2007). "The Butyrylcholinesterase Knockout Mouse as a Model for Human Butyrylcholinesterase Deficiency". Journal of Pharmacology and Experimental Therapeutics. 324 (3): 1146–54. doi:10.1124/jpet.107.133330. PMID 18056867.
- ^ Daniel R Alexander. (2006). "Pseudocholinesterase Deficiency". eMedicine Retrieved June 16, 2008
- ^ "Cholinesterase Test". Lab Tests Online. Retrieved 21 July 2014.
External links
- Cholinesterase Test - Lab Tests Online