Table 2.

Comparison of antiviral agents for chronic hepatitis B

Antiviral agents	Immunomodulators			Nucleos(t)ide analogues
	IFN-α	PEG-IFN-α	Thymosin	Lamivudine	Adefovir	Entecavir	Telbivudine	Tenofovir
Route	SC	SC	Oral	Oral	Oral	Oral	Oral	Oral
Dose	5-10 MIU tiw	180 μg qw	1.6 mg biw	100 mg od	10 mg od	0.5-1 mg od	600 mg od	300 mg od
Year approved	1992	2005	Asia only	1998	2002	2005	2006	2008
Antiviral effects
HBV DNA	37	30	42	36-40	21	67	60	76
HBsAg clearance	++	++	N/A	-	-	+	-	-
HBeAg seroconversion	20-40	27	40	18-20	12	21	22	21
ALT normalization		39	42	62-77	48	68	77	68
Histological improvement		38	N/A	56-62	53	72	65	74
Side effects	Many	Many	Negligible	Negligible	Nephrotoxicity	Negligible	Negligible	Nephrotoxicity
Contraindications	Numerous	Numerous	Uncommon	Uncommon	Uncommon	Uncommon	Uncommon	Uncommon
Drug resistance (treatment-naïve patients)
1 yr	None, but non-response			24	None	0	4	0
2 yr				38	3	0.2	25	0
> 5 yr				80	29	1	N/A	0
Drug resistance (LAM resistant patients)
2 yr	None, but non-response			N/A	25	9	N/A	0
4 yr				N/A	N/A	39	N/A	0

PEG-IFN: Pegylated interferon; SC: Subcutaneous; tiw: Three times a week; qw: Once a week; biw: Twice a week; od: Once daily; ALT: Alanine transaminase; ETV: Entecavir; LAM: Lamivudine; ADV: Adefovir; TBV: Telbivudine; TDF: Tenofovir disoproxil fumarate; N/A: Not applicable.