AstraZeneca posted a 10% rise in fourth quarter earnings, but the drug giant's shares fell back as it predicted 2010 revenues would be hit by the loss of exclusive rights to sell certain drugs.The company is also planning to cut 8,000 jobs from its global workforce of 63,000.The company saw pre-tax profits rise to $2.9m in the fourth quarter from $2.6m over the same period the previous year as revenues climbed to $8.9m from $8.2m.Revenue was boosted by strong sales of high blood pressure treatment Toprol-XL, which benefited from the withdrawal of two generic competitors in the US, and of swine flu vaccines. Sales in 2010 will be affected by the expected loss of market exclusivity for breast cancer treatment Arimidex and for Pulmicort Respules, used to treat asthma, in the US, the company said, predicting that it will see 'up to a mid single-digit decline' in revenues.