Adefovir dipivoxil and peginterferon alfa-2a for the treatment of chronic hepatitis B

Peginterferon alfa-2a

3.1 Peginterferon alfa-2a (Pegasys, Roche) has UK marketing authorisation for the treatment of HBeAg-positive or HBeAg-negative chronic hepatitis B in adults with compensated liver disease and evidence of viral replication, increased ALT and histologically verified liver inflammation and/or fibrosis. Peginterferons are formed by attaching strands of polyethylene glycol (PEG) to the interferon molecules. This slows the rate of absorption and excretion of interferon, reducing the fluctuations in serum level that occur with unmodified interferon. Peginterferons are administered once a week, compared with three or more times a week for the unmodified form.

3.2 Peginterferons have a range of adverse effects similar to those of interferons. These include influenza-like symptoms such as fever, chills, myalgias, arthralgias and headache, which are most likely to occur at the start of treatment and seldom require discontinuation of treatment. Depletion of platelets and white blood cells is common. Other adverse effects include depression, anxiety or emotional lability, which may be severe. Cardiovascular adverse effects include hypertension or hypotension, arrhythmias, oedema, myocardial infarction or stroke. Interferons are contraindicated in chronic hepatitis with decompensated cirrhosis of the liver. For full details of side effects and contraindications, see the 'Summary of product characteristics'.

3.3 A prefilled syringe containing 180 micrograms of peginterferon alfa-2a costs £132.06 (excluding VAT, 'British national formulary', 50th edition ['BNF'50]). The usual dose is 180 micrograms once a week. Costs may vary in different settings because of negotiated procurement discounts.

Adefovir dipivoxil

3.4 Adefovir is structurally related to the purine base adenine. It is converted intracellularly to the diphosphate, which inhibits the synthesis of hepatitis B virus DNA through competition for the enzyme reverse transcriptase and incorporation into the viral DNA. Adefovir is not well absorbed after oral administration so is given by mouth as the prodrug adefovir dipivoxil.

3.5 Adefovir dipivoxil (Hepsera, Gilead) has UK marketing authorisation for the treatment of chronic hepatitis B in adults with:

3.6 The most commonly reported adverse effects for adefovir dipivoxil are gastrointestinal effects including nausea, flatulence, diarrhoea and dyspepsia. Increases in serum creatinine are common but usually mild to moderate. However, cases of renal impairment and acute renal failure have been reported. For full details of side effects and contraindications, see the 'Summary of product characteristics'.

3.7 A pack containing 30 days' supply of adefovir dipivoxil 10 mg tablets costs £315.00 (excluding VAT, 'BNF'50). Costs may vary in different settings because of negotiated procurement discounts.