Quarterly results for Bristol Myers-Squibb and AstraZeneca show patent losses continue to roil the balance sheets.

Generic Plavix trimmed sales for BMS’s quarter, which fell 27%, to $4 billion, compared to the same period last year, largely due to generic versions of cardio drugs Plavix and Avapro. US sales plummeted 44% during the quarter while international sales rose 6% vs. the year-ago period. The major growth story in percentages was for melanoma drug Yervoy, which posted $229 million in Q1 sales, a 49% increase over the same period last year, while diabetes medication Onglyza brought in sales of $202 million, a 25% increase over Q1 2012.

Some of the same dynamics were at play for AstraZeneca, which closed the first quarter of the year with a 13% slide in sales, to $4 billion, compared to $7 billion for the same period last year. Generic forms of mood drug Seroquel IR and heart pill Atacand were behind the shrinkage, as was Canada’s move to unleash a generic knockoff of the statin Crestor. US sales dropped 16%, largely due to generic Seroquel competition, and sales for the Seroquel franchise, which includes Seroquel IR and Seroquel, were down 60% vs. the same period last year. A multi-phase restructuring helped shrink the company’s R&D spend to $1.3 billion, a 6% drop from the year-ago  period. SG&A costs fell to $2.6 billion, 3% less than was spent for the prior-year period.

The respiratory division saw growth with Symbicort sales rising 14% over the same period last year, and Pulmicort rising 3% quarter-on-quarter, while oncology drug Irissa led the category, with sales rising 20% over the same period last year.