Pfizer Inc (PFE.N), which closed its $14 billion acquisition of Medivation Inc in September, reported a lower-than-expected profit, hit by lower demand for products set to go off patent.

The largest U.S. drugmaker posted a net income $775 million, or 13 cents per share, in the fourth quarter, compared with a loss of $172 million, or 3 cents per share, a year earlier.

Excluding items, the company earned 47 cents per share, missing the average analysts' estimate of 50 cents per share, according to Thomson Reuters I/B/E/S.

The company's revenue slipped 3 per cent to $13.63 billion, due to a strong dollar and fewer selling days compared to the year-ago quarter, but was roughly in line with estimates.

Those lost days resulted in a negative impact on quarterly revenue by about $750 million compared to the prior-year quarter.

The company forecast adjusted profit of $2.50-$2.60 per share on revenue of $52 billion-$54 billion in 2017. Analysts on average were expecting earnings of $2.56 per share and revenue of $54.03 billion.