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Phenobarbital Treatment


For a small number of people the nature of the genetic error is such that the gene is sufficiently effective to normally maintain bilirubin at safe levels. Bile analysis for these people typically shows significant amounts of conjugated bilirubin. Even for such people care must be taken. Illness or accident could cause unconjugated blood bilirubin to increase rapidly beyond their system's ability to cope. There are a small number of cases (not of Type 1) where an individual has reached late teens without being aware of, or having any treatment for, CNS and only then had an emergency or neurological episode that caused it to be diagnosed.

While there are some treatment options that can be used in emergency situations under intense medical supervision, the two standard treatments for ongoing management of CNS are the use of phenobarbital and blue light phototherapy.

For some CNS people, controlled doses of phenobarbital helps to maintain acceptable bilirubin levels. Intensive blue light phototherapy is the standard management technique where:

  • people do not respond to phenobarbital; or
  • phenobarbital alone does not provide sufficient control; or
  • the side effects of phenobarbital for a CNS person outweighs its advantages.


In addition to glucuronyl transferase for the removal of bilirubin, the liver produces a number of related enzymes for removal from blood of a number of other unwanted products. When any of these unwanted products are present, the production of all related enzymes may be stimulated.

Where the cause of Crigler Najjar Syndrome is a defect on that part of the gene that determines the rate of glucuronyl transferase enzyme production, the addition of phenobarbital can stimulate the rate of enzyme production and thus assist bilirubin removal. For some CNS people phenobarbital alone is sufficient to keep bilirubin at relatively safe levels. For others, phenobarbital is used in conjunction with phototherapy.

For many people with CNS the fault is not in the rate of enzyme production, but is a flaw in the actual enzyme produced. In these circumstances using phenobarbital to increase the rate of enzyme production of the faulty enzyme would not provide the benefits required.

Like most drugs, phenobarbital has some well-established side effects, which may include drowsiness. The extent of side effects is different for different people. Whether phenobarbital should be used is a decision that should be made by individuals in consultation with an experienced clinician, taking into consideration all of the factors, including lifestyle.


Yes. Some other drugs may perform a similar function of stimulating enzyme production. They may suit some people better than phenobarbital. Many drugs have different names in different parts of the world. Phenobarbital and any alternatives must only be tried under specialised medical supervision.


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