Table 1.

Pros and cons of each nucleos(t)ide analogue therapy for the treatment of chronic hepatitis B infection

Nucleos(t)ide analogue	Regimen	Pros	Cons
Lamivudine	100 mg daily	First licensed agent	Highest incidence of resistant mutations of M204V/I substitution (20% at year 1, 70% at year 5)
		Well established safety and efficacy record
		Lowest cost	Adverse effects including hepatitis flare ups, hepatic decompensation and even death
Adefovir dipivoxil	10 mg daily	Low drug resistance rate, and no cross resistance with other nucleos(t)ide analogs	Incidence of resistant mutations of N236T and/or A181V substitution (29% at year 5)
			Adverse effects including renal tubular acidosis with hypophosphataemia when treatment is prolonged
Telbivudine	600 mg daily	Higher seroconversion rate	Incidence of resistant mutations of M204I mutation (5% at year 1)
			Adverse effects including myopathy and neuropathy
Entecavir	1.0 mg daily	Anti-HBV effect	Incidence of resistant mutations of T184G or M250V (1.2% at year 5) (I169T and M250V, or T184G and S202I if also lamivudine-resistant)
		Lowest rate of resistance
			Most expensive
Tenofovir disoproxil	300 mg daily	More potent in reducing HBV load in patients with prior failure or resistance to lamivudine and/or adefovir	No resistant mutations reported at year 3

HBV: Hepatitis B virus.