Global pharmaceutical giant AstraZeneca (AZN -1.12%) reported its fourth-quarter results in the wee hours of the morning today, pointing to ongoing struggles as it attempts to adapt to declining sales stemming from the loss of patent exclusivity on key drugs.

For the quarter, AstraZeneca delivered a 6% decline in revenue to $6.84 billion (a 4% decline when using constant currency figures) as GAAP EPS plummeted due to a whopping $1.76 billion one-time impairment for Bydureon. Excluding this one-time charge, adjusted EPS fell 28% to $1.23 per share.

As has been the case for years now, AstraZeneca struggled with the loss of previously key drugs to generic competition, including schizophrenia and bipolar disorder drug Seroquel, whose sales dropped 22% to $372 million on increased generic competition. Top-sellers Crestor, which treats high cholesterol levels, and Nexium, which is a heartburn medication and is set to lose its exclusivity this coming May, also witnessed a drop in revenue of 8% and 3%, respectively.

Providing some spark to its top line were sales of Symbicort, which rose 11% to $976 million, as well as anticoagulant drug Brilinta (known as Brilique in the EU), whose sales more than doubled to $92 million from $38 million in the year-ago period.

Broken down by region, U.S. revenue dropped 7%, hurt by key patent losses and higher costs created by Obamacare's health care reforms, while European and rest of world revenue both declined by 2%. China and South Korea were two notable standouts, with revenue up 21% and 17%, respectively.

Looking ahead, AstraZeneca now anticipates a low-to-mid single-digit decline in revenue at a constant exchange rate in fiscal 2014, with core EPS projected to decline by the mid-teens in terms of percentage from the $5.05 reported this morning for fiscal 2013. Furthermore, AstraZeneca is forecasting 2017 revenue will be more or less in line with the $25.7 billion reported this morning for the full-year.