Hepatitis B virus (HBV) infection is a major global health problem, with over 250 million people chronically infected worldwide. Chronic hepatitis B (CHB) infection can lead to serious complications like cirrhosis, liver failure, and hepatocellular carcinoma. Antiviral therapy is the mainstay of treatment for CHB, aimed at long-term suppression of HBV replication to prevent disease progression. This article provides an overview of antiviral therapy for CHB in adults, including background on CHB, risk factors, and current treatment options.
Understanding Chronic Hepatitis B
Hepatitis B virus causes inflammation of the liver. Acute HBV infection may resolve spontaneously in over 90% of adults. However, up to 10% develop chronic infection, with the risk higher in those infected as infants or young children. In CHB, HBV persists for over 6 months, with continuing liver inflammation and damage.
CHB has an initial immune-tolerant phase with high HBV DNA but normal liver enzymes. This progresses to an immune-active phase with elevated liver enzymes reflecting immune-mediated liver inflammation. Without treatment, periods of remission and flares occur, with the eventual development of cirrhosis and liver cancer in 15-40% of patients over 2-3 decades.
Risk Factors For Chronic Hepatitis B
Risk factors for developing chronic HBV infection include:
- Acquiring infection around the time of birth or in early childhood
- Male gender
- Exposure to infected blood or body fluids
- Intravenous drug use
- High HBV DNA or hepatitis B e antigen (HBeAg) positivity in acute infection
- Genetic factors
Screening and vaccination are key public health measures for preventing new HBV infections. However, existing CHB requires long-term antiviral therapy.
Antiviral Therapy For Chronic Hepatitis B Viral Infection In Adults
Goals of Treatment
The goals of antiviral therapy in CHB are to:
- Achieve sustained suppression of HBV replication
- Prevent the progression of liver disease to cirrhosis and liver cancer
- Improve the quality of life and survival
Current treatment cannot eradicate HBV infection; life-long therapy is required in most patients.
Options for Antiviral Therapy
Seven medications are currently approved for CHB treatment:
- Interferon-alfa: Given as injections, has antiviral and immune-modulating effects. Disadvantages include frequent side effects and the need for injections.
- Nucleoside/nucleotide analogues: Includes lamivudine, telbivudine, entecavir, tenofovir disoproxil fumarate and tenofovir alafenamide. Given as oral tablets, well tolerated. Highly effective in suppressing HBV DNA. The disadvantage is possible drug resistance with some agents.
- Pegylated interferon: Longer-acting injectable form of interferon with possibly greater efficacy than standard interferon.
The American Association for the Study of Liver Diseases recommends nucleos(t)ide analogues as first-line agents for CHB treatment. Entecavir, tenofovir or pegylated interferon are preferred options. Other agents may be used if these are unavailable or not tolerated.
Treatment is generally recommended for immune-active CHB with elevated ALT/AST levels. HBeAg-positive patients should be treated until HBeAg loss/seroconversion is achieved. HBeAg-negative patients need long-term therapy. Patients with cirrhosis require lifelong antiviral therapy.
Regular monitoring of liver enzymes, HBV DNA levels, medication adherence, and side effects is important during treatment. Resistance testing should be performed if a viral breakthrough is suspected. Combination therapy may help overcome drug resistance.
CHB is a major health burden worldwide, with high risks of cirrhosis and liver cancer without treatment. Potent antiviral agents can effectively suppress HBV replication and prevent complications. However, life-long therapy is usually required. Access to affordable generics worldwide is important to enable the widespread use of antiviral therapy for CHB. With appropriate treatment, prevention of end-stage liver disease and increased survival is achievable for most patients with chronic hepatitis B infection.
A: Diagnostic blood tests include hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), hepatitis B virus DNA levels, and liver enzymes ALT and AST. Positive HBsAg for over 6 months confirms chronic HBV infection.
A: Monitoring every 3-6 months with blood tests for liver enzymes, HBV DNA, medication side effects, and adherence is recommended. More frequent monitoring may be needed in certain situations.
A: Many patients with CHB infection are asymptomatic. When present, symptoms may include fatigue, nausea, poor appetite, abdominal discomfort, joint pain, or jaundice. Symptoms correlate with active liver inflammation.
A: No. The antiviral medications used to treat hepatitis B virus are different from those used to treat hepatitis C virus. There is no antiviral drug currently available that works against both hepatitis B and C.
A: Currently available antiviral therapy for chronic hepatitis B suppresses viral replication but does not completely eliminate or cure the infection. Life-long treatment is typically required to manage the disease. A true cure may become possible in the future with improved antiviral drugs or immune-based therapies.