2 The technology
2.1 Tenofovir disoproxil (Viread, Gilead) is a nucleotide analogue. It works by blocking the enzyme reverse transcriptase, which is responsible for hepatitis B virus (HBV) replication. Tenofovir disoproxil has a marketing authorisation in the UK for the treatment of chronic hepatitis B in adults with compensated liver disease, with evidence of active viral replication, persistently elevated serum alanine aminotransferase (ALT) levels and histological evidence of active inflammation and/or fibrosis.
2.2 Adverse events associated with the use of nucleotide analogues include lactic acidosis and progression of hepatomegaly. Additional adverse events reported for tenofovir disoproxil include headache, fatigue and gastrointestinal disorders. For full details of side effects and contraindications, see the summary of product characteristics.
2.3 The acquisition cost of tenofovir disoproxil (excluding VAT; 'British national formulary' [BNF] edition 56) is £255.00 for a 30-tablet pack. Costs may vary in different settings because of negotiated procurement discounts. Tenofovir disoproxil is licensed for use in adults over 18 years. The dosage is a once-daily tablet of 245 mg. The optimal treatment duration is currently unknown. Costs may vary in different settings because of negotiated procurement discounts.