IMS Health, the world's leading provider of market intelligence to the pharmaceutical and healthcare industries, reported an annual US prescription sales growth of just 1.3 per cent in 2008 at $291 billion as against $287.6 billion in the previous year. This growth is the lowest during the last five years.

Factors influencing the market's slower growth in 2008 included higher demand for less-expensive generic drugs, lower new product sales, and reduced consumer demand due to the economic turndown. The sales of lipid regulators therapeutic class declined by 11.6 per cent during 2008 to $14.5 billion from $16.4 billion in the previous year. Further, the sales of proton pump inhibitors and erythropoietins therapeutic classes in US declined by 2.1 per cent and 17.2 per cent respectively to $13.9 billion and $7.2 billion respectively.

Despite lower sales, Pfizer maintained its top position with US sales of $20.5 billion during 2008 as against $23.6 billion in the previous year. This was followed by Glaxosmithkline with the US sales of $18.4 billion, AstraZeneca $16.3 billion, Johnson & Johnson $16 billion and Merck & Co 15.5 per cent.

Pfizer's Lipitor registered lower growth in US sales by 3.7 per cent to $7.8 billion during 2008 as compared to $8.1 billion in the previous year. Nexium of AstraZeneca remained the second largest prescription drug in US with sales of $5.9 billion and Plavix of Bristol-Myers Squibb at third rank with sales of $4.9 billion.

Dispensed prescription volume in the US grew at a 0.9 per cent pace to $3,843 million from $3,807 million in the previous year. Across the major therapy classes, lipid regulators were the most widely dispensed retail prescription medications on a volume basis in 2008, followed by codeine and combinations, anti-depressants, ACE inhibitors and beta blockers. In terms of overall prescription sales sold through both retail and non-retail channels, anti-psychotics led all therapy classes followed by lipid regulators, proton pump inhibitors and seizure disorder medications.