Forest Laboratories Inc.’s fiscal fourth-quarter earnings plunged 76 percent, as the drug developer’s revenue continued to take a hit from a key patent loss.

The New York company said Tuesday that it earned $45.4 million, or 17 cents per share, in the three months that ended March 31. That compares with earnings of $192.7 million, or 72 cents per share, in last year’s quarter.

Excluding acquisition-related items, earnings totaled 25 cents per share. Revenue fell 22 percent to $821.7 million.

Forest’s sales have dropped since its anxiety and depression drug Lexapro lost patent protection in March 2012. Revenue from other drugs has climbed. Sales of the Alzheimer’s disease treatment Namenda rose nearly 12 percent to $438.8 million, and the company also recorded more revenue from some newer drugs.

Sales of the major depressive disorder treatment Viibryd jumped 79 percent to $44.6 million, and revenue from the high blood pressure treatment Bystolic rose 36 percent to $132 million.

For the full year, Forest Laboratories lost $32.1 million, or 12 cents per share, on $3.13 billion in revenue. It was the company’s first annual loss since fiscal 1997

Chairman and CEO Howard Solomon said in a statement that Forrest Laboratories hit an earnings trough created by the loss of the Lexapro patent and expenses that came from launching several drugs. But he said the drug developer appears to be headed up and he expects earnings to grow, helped by the newer products.

Forest Laboratories expects adjusted earnings of 80 cents to $1 per share on about $3.5 billion in fiscal 2014.

Its shares rose 69 cents to $36.83 in morning trading amid broader market gains.