What is Lamivudine?:
- Lamivudine is an antiviral agent that blocks the multiplication of hepatitis B virus.
How is Lamivudine Administered?:
- The dose regimen is usually 100mg (one tablet) once a day.
- The duration of treatment has not been defined.
- Currently, it seems that a minimum of 1 year treatment is necessary.
- Treatment may be discontinued in patients who have cleared hepatitis B e antigen and hepatitis B viral DNA.
- Patients with kidney failure may need reduced dosing while patients with combined HIV and hepatitis B infection require a higher dose.
Who May Benefit from Lamivudine?:
- Adults with chronic hepatitis B - hepatitis B surface antigen positive for at least 6 months, markers of active infection - hepatitis B DNA positive and evidence of liver disease - abnormal liver enzymes.
- Lamivudine is not yet approved for children, patients with inactive liver disease (normal liver enzymes), or patients with advanced cirrhosis.
How Effective is Lamivudine?:
- Response is usually assessed by loss of hepatitis B e antigen and hepatitis B virus DNA, detection of hepatitis e antibody, and normalization of liver enzymes.
- Approximately 20% of patients will respond after 1 year of treatment. Most (80-90%) who achieve a response can maintain the response after stopping treatment.
What are the Side Effects?:
- rare cases of pancreas inflammation (pancreatitis)
- numbness or tingling of the legs
- some patients may develop flares or increases in liver enzymes when lamivudine is stopped
- in doses used for chronic hepatitis B, very few side effects are seen
What is Meant by Lamivudine Resistance?:
- Approximately 15-30% of patients develop resistant hepatitis B virus mutations (changes in the virus gene) after 1 year of treatment.
- The risks of resistance increase with longer durations of treatment.
- Patients with resistance may develop breakthrough infection - reappearance of hepatitis B virus DNA and increased liver enzymes.
What Can be Done for Patients with Resistance?:
- At the moment, the recommendations are to leave patients with resistant virus on Lamivudine, since most patients still have low levels of the original (wild type) virus that may respond to lamivudine.
- New drugs, such as adefovir dipivoxil, are being tested to determine if they can suppress the lamivudine resistant hepatitis B virus.
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