Tobacco use is the single most preventable cause of death, disability and disease in the world and is projected to be the leading cause of death and disability across all developed and developing countries by 2020. Nicotine, the primary active ingredient of cigarettes that contributes to physical dependence, acts on nicotine receptors in the central nervous system and leads to the release of neurotransmitters (such as dopamine). Like other drugs of abuse, nicotine is thought to produce reinforcing effect by activating the mesocorticolimbic dopamine system. A wide variety of cessation treatments of nicotine dependence is commercially available, yet only 2 general approaches have received empirical validation: behavioral intervention (including 5 As brief intervention) and pharmacotherapy. The evidences show that 5 As brief intervention is one of the most cost-effective treatments in clinical work for busy physicians. Three types of medications have been available in market for smoking cessation treatment: nicotine replacement treatment (NRT, i.e., transdermal patch, gum, inhaler, nasal spray, and lozenge), sustained release bupropion and varenicline. Varenicline, a novel alpha4beta2 nicotinic receptor partial agonist, is effective for tobacco dependence. Phase III trials suggest that it is more effective than NRT and bupropion SR. The safety profile of varenicline is excellent, with the most commonly occurring adverse events, nausea, typically mild and well tolerated. However, new safety warnings are added to the varenicline label because of post-marketing report including agitation, depression and suicidality. A causal connection between varenicline use and these symptoms has not been established.
Benzazepines ; adverse effects ; therapeutic use ; Bupropion ; therapeutic use ; Dopamine Uptake Inhibitors ; therapeutic use ; Humans ; Nicotinic Agonists ; adverse effects ; therapeutic use ; Quinoxalines ; adverse effects ; therapeutic use ; Smoking Cessation ; methods ; psychology ; Tobacco Use Disorder ; therapy ; Varenicline

The introduction of direct-acting antiviral agents (DAAs) has markedly improved the sustained virological response (SVR) rates in patients with chronic hepatitis C. Currently, four classes of DAAs targeting three HCV proteins (NS3, NS5A, and NS5B) have been approved for treatment in many countries. Since drugs show advantages and disadvantages, use of a combination of two or more DAAs with different targets or addition of ribavirin in a difficult-to-treat patient shows an SVR rate of ~90% after 12 weeks of treatment or expanded treatment for 24 weeks. Various types of DAA are awaiting approval which will improve the treatment of chronic hepatitis C virus genotype 1 infection. However, high costs, drug resistance and interactions between various drugs remain to be overcome. With further advances in the development of antiviral agents, it could be expected that in the near future, there will be DAAs that are affordable and cost effective, require shorter treatment duration, effective in a broad range of patients, and have less side effects and drug-drug interactions.
Antiviral Agents/*therapeutic use ; Drug Therapy, Combination ; Genotype ; Hepacivirus/*genetics/isolation & purification ; Hepatitis C/*drug therapy/virology ; Humans ; Interferon-alpha/therapeutic use ; Practice Guidelines as Topic ; Quinoxalines/therapeutic use ; Republic of Korea ; Sofosbuvir/therapeutic use