Drugmaker Bristol-Myers Squibb Co. on Thursday posted a 45 percent drop in first-quarter profit as reduced spending and a sharply lower tax rate couldn’t make up for plunging sales from increased generic competition to blood thinner Plavix.

Revenue from Plavix, which had been the world’s second best-selling drug until its U.S. patent expired last May, nosedived 95 percent. That, along with generic competition that cut sales of blood pressure drugs Avapro and Avalide by 78 percent, dragged down total company sales by 27 percent.