AZT comes off patent: generic versions approved for US market

On 17 September 2005, AZT, the first approved antiretroviral drug, manufactured and marketed by GSK, came off patent. On 19 September, the FDA approved several generic formulations of AZT for the US market.

Previously, the products had been only tentatively approved and were not available in the United States because patent or market exclusivity blocked their approval for domestic marketing. With the expiration of those patents, the following products from two Indian and one US manufacturer have received full marketing authorisation for the United States:

ii) zidovudine tablets, 300 mg and oral solution, 50 mg/5mL, manufactured by Aurobindo Pharma

These are the first generic versions of the already-approved Retrovir brand manufactured by GlaxoSmithKline to be approved for marketing in the U.S. FDA previously determined, as part of a tentative approval action, that these products meet all U.S. manufacturing quality and clinical safety and efficacy standards.

Comment

The European patent for AZT ends in March 2006. When this occurs, it is unclear how the availability of generic AZT will affect ARV drug costs in the UK. BHIVA guidelines already highlight cost of drugs in the UK. The increasing pressure on ARV and related drug budgets is likely to restrict choice in the future. The guidelines also recommend not using AZT in first-line therapy because of the association with lipoatrophy.

The cost versus benefit arguement over use of AZT could easily become more important next year.

Patient awareness of the issue of cost of treatment and the implications for future costs is currently low, but inclusion of a cost comparison table in the BHIVA guidelines should send a clear signal that cost may become an increasing factor in deciding Trust and hospital purchasing and prescribing policy.