2021 Lobato et al. Citation: Lobato GDS, Farias AA, Belo AMB, et al. Drug treatment of chronic hepatitis b in Brazil: a review. Gastroenterol Hepatol Open Access. 2021;12(6):182‒185. DOI: 10.15406/ghoa.2021.12.00483 observed. Electrolyte disturbances occasionally occur in association with anorexia and dehydration.16 The hematopoietic system may be affected, generating transient leukocytopenia which has occurred in one third of half of patients receiving recombinant human interferon alpha 2a. Thrombocytopenia and decreased hemoglobin are seen in some patients with bone marrow depression. Severe normality in the hematopoietic system can be reversed 7 to 10 days after discontinuation of recombinant human interferon alpha 2a therapy. 2,23 PEG Interferon alpha-2a PEG-interferon alfa-2a is a biological response transformer. The coupling of PEG reagent (bis-monomethoxypolyethylene glycol) with interferon alfa-2a forms a pegylated interferon alfa-2a. According to ANVISA data, interferon bind to specific receptors on the cell surface, initiating a complex pathway of intracellular signaling and rapid activation of gene transcription. Interferon-activated genes articulate several biological effects, achieving inhibition of viral replication in infected cells, inhibition of cell proliferation and immunomodulation.23 Alpha interferon can affect the oxidative metabolic process, reducing the activity of CYP450 liver microsomal enzymes. However, subcutaneous administration of 180mg Pegasys® once weekly for 4weeks to healthy male subjects had no effect on enzymes.23 According to ANVISA’s CPTG for Hepatitis B and co-infections, the most common reactions with no defined incidence are abdominal pain, lack of appetite, diarrhea, nausea, decreased neutrophils in the blood, anemia, decreased lymphocytes in the blood, joint pain, muscle pain, hair loss, itching, depression, dizziness, fatigue, headache, insomnia, irritability.2,23 Conclusion The mechanisms of action of drugs recommended for the treatment of chronic hepatitis B in Brazil can be either by the inhibitory action of viral replication or by modulation of the immune system, causing several adverse reactions. The evolution of drugs used in the treatment of chronic hepatitis B is necessary, in order to achieve a more effective treatment, taking into account that the patient must have greater adherence to treatment, always seeking to avoid interruptions. Therefore, further research is needed so that the mechanism of action and adverse reactions of current drugs are evidenced, so that an advance in the production of new drugs can occur, always aiming for an evolution in the treatment of chronic hepatitis B. Acknowledgments We are grateful to all colleagues at the University of Amazonia who contributed directly or indirectly. Conflicts of interest We declare there is no conflict of interest. Funding None. References 1. World Health Organization. Hepatitis B. Geneva: World Health Organization; 2021. 2. Brasil. Protocolo Clínico e Diretrizes Terapêuticas para Hepatite B e Coinfecções. 2017. 3. Sherman M, Shafran S, Burak K, et al. Management of chronic hepatitis B: Consensus guidelines. Can J Gastroenterol. 2007;21(Suppl C):5C– 24C. 4. WHO urges countries to invest to eliminate viral hepatitis. Geneva: World Health Organization; 2021. 5. Almeida AM, Ribeiro AQ, Menezes de Pádua CA, et al. Efficacy of adefovir dipivoxil, entecavir and telbivudine for the treatment of chronic hepatitis B: systematic review. Rev Soc Bras Med Trop. 2010;43(4). 6. Aspinall EJ, Hawkins G, Fraser A, et al. Hepatitis B prevention, diagnosis, treatment and care: A review. Occup Med (Lond). 2011;61(8):531-540. 7. Bhattacharya D, Thio CL. Review of hepatitis B therapeutics. Clin Infect Dis. 2010;51(10):1201-1208. 8. Koumbi L. Current and future antiviral drug therapies of hepatitis B chronic infection. World J Hepatol. 2015;7(8):1030–1040. 9. Wiens A, Correr CJ, Pontarolo R. CHRONIC HEPATITIS B: A REVIEW ON CLINICAL AND THERAPEUTIC ASPECTS. Visão Acadêmica. 2010;11(2). 10. Lam YF, Yuen MF, Seto WK, et al. Current antiviral therapy of chronic hepatitis B: Efficacy and safety. Curr Hepat Rep. 2011;10(4):235–243. 11. Farrell GC, Teoh NC.