The Food and Drug Administration said Tuesday it has sent a warning letter to drug distributor McKessson for allegedly shipping “illegitimate” opioid products and failing to properly handle and investigate the incidents. Specifically, the FDA is accusing McKesson of failing to identify, quarantine and investigate drug shipments that had been tampered with. Some of the bad shipments were discovered at three Rite Aid pharmacies in Michigan. This is the first time the FDA has issued a warning letter under the…