This excerpt taken from the ELN 6-K filed Sep 29, 2009.
Our product revenue may vary periodically due, in part, to buying patterns of our wholesalers and distributors. In the event that wholesalers and distributors determine, for any reason, to limit purchases of our products, sales of those products would be adversely affected. In 2008, 66.4% of our sales were made to five customers of which the top customer accounted for 29.2% of our sales. We are therefore dependent on a limited number of wholesalers and distributors. In addition, wholesalers and distributors may order products in larger than normal quantities prior to anticipated price increases for those products. This excess purchasing in any period could cause sales of those products to be lower than expected in subsequent periods.