Tyzeka medication for Hepatitis B treatment - How effective is this medication, what is the right dose by Ray Sahelian, M.D.
April 6 2016

Tyzeka (telbivudine) is used for the treatment of adults with chronic hepatitis B (HBV), a viral infection that attacks the liver and can cause lifelong infection, scarring of the liver (cirrhosis), and eventually liver cancer, liver failure, and death. Tyzeka is a new molecular entity, a medication containing an active substance that has never before been approved for marketing in any form in the United States. T yzeka is not a cure for hepatitis B, and long-term treatment benefits of this drug are not known. Use of Tyzeka has not been shown to reduce the risk of transmission of HBV to others through sexual contact or blood contamination.

Perinatal or mother-to-child transmission (MTCT) of hepatitis B virus (HBV) remains the major risk factor for chronic HBV infection worldwide. In addition to hepatitis B immune globulin and vaccination, oral antiviral therapies in highly viremic mothers can further decrease MTCT of HBV.

Tyzeka Research for hepatitis B
Tyzeka was studied in a year-long international clinical trial in 1,367 patients with chronic HBV. Three-quarters of the trial participants were male, and all were 16 years of age or older. The trial produced evidence of antiviral effectiveness, including the suppression of hepatitis B virus, and improvement in liver inflammation comparable to Epivir-HBV (lamivudine), one of five other medications approved to treat patients with chronic HBV.

J Viral Hepat. 2013. Efficacy and safety of continuous 4-year telbivudine treatment in patients with chronic hepatitis B. In the phase-III GLOBE/015 studies, telbivudine demonstrated superior efficacy vs lamivudine during 2-year treatment in HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB). After completion, 847 patients had an option to continue telbivudine treatment for further 2 years. A total of 596 (70%) of telbivudine-treated patients, who were serum HBV DNA positive or negative and without genotypic resistance to telbivudine at the end of the GLOBE/015 trials, were enrolled into a further 2-year extension study. A group of 502 patients completed 4 years of continuous telbivudine treatment and were included in the telbivudine per-protocol population. Amongst 293 HBeAg-positive patients, 76.2% had undetectable serum HBV DNA and 86.0% had normal serum ALT at the end of 4 years. Notably, the cumulative rate of HBeAg seroconversion was 53.2%. Amongst 209 HBeAg-negative patients, 86.4% had undetectable HBV DNA and 89.6% had normal serum ALT. In patients who had discontinued telbivudine treatment due to HBeAg seroconversion, the HBeAg response was durable in 82% of patients (median 111 weeks of off-treatment follow-up). The cumulative 4-year resistance rate was 10.6% for HBeAg-positive and 10.0% for HBeAg-negative patients. Most adverse events were mild or moderate in severity and transient. Renal function measured by estimated glomerular filtration rate (eGFR) increased by 14.9 mL/min/1.73 m(2) (16.6%) from baseline to 4 years (P < 0.0001). In conclusion, in HBeAg-positive and HBeAg-negative CHB patients without resistance after 2 years, two additional years of telbivudine treatment continued to provide effective viral suppression with a favourable safety profile. Moreover, telbivudine achieved 53% of HBeAg seroconversion in HBeAg-positive patients.

Tyzeka Side Effects, adverse events, danger
In clinical studies most common Tyzeka side effects were elevated CPK (creatinine phosphokinase, an enzyme that is present in muscle tissue and is a marker for breakdown of muscle tissue), upper respiratory tract infection, fatigue, headache, abdominal pain and cough. After several weeks to months of Tyzeka use, some patients developed additional side effects ranging from transient muscle pain to muscle weakness. Those who developed muscle weakness experienced significant improvement in their symptoms when Tyzeka was discontinued. Muscle pain and damage from Tyzeka use appears to be a common side effect. Among drugs in the same class as Tyzeka, some cases of lactic acidosis (too much acid in the body due to buildup of lactic acid) and severe enlargement and accumulation of fat in the liver, including fatal cases, have been reported.

Stopping Tyzeka
Patients should stop it after a discussion with their doctor. As has happened with other forms of treatment for hepatitis B, some patients who discontinued Tyzeka experienced a sudden and severe worsening of their hepatitis B. Therefore, patients who discontinue Tyzeka should be closely monitored by their doctor for at least several months.

Tyzeka is a prescription medication manufactured by Novartis Pharma Stein AG, Stein, Switzerland and marketed and distributed by Idenix Pharmaceuticals, Inc., Cambridge, MA.