(Shire CEO Flemming OrnskovReuters)

While Republicans in Congress try to overhaul the healthcare system, the pharmaceutical lobby has largely been silent — at least in public.

But that doesn't mean drugmakers don't have skin in the game, or that they aren't doing anything to make sure they're represented.

For Flemming Ornskov, the CEO of $50 billion drugmaker Shire, that's meant pushing back against efforts to dismantle the parts of the Affordable Care Act that ensure patients get continuous and lifetime coverage.

Shire, which is headquartered in Dublin, counts on the US for as much as two-thirds of its annual revenue. It's known for making ADHD medicine, like Adderall and Vyvanse, and its focus on rare diseases like the blood disorder hemophilia, many of which affect people starting at an early age.

Ornskov said he's concerned about whether the legislation would make changes to how people with existing illnesses get coverage. In both the bill that passed the House and a revised version of the Senate bill, there is the possibility that people with so-called "preexisting conditions" might have a harder time getting affordable and comprehensive healthcare compared to otherwise healthy people.

As such, Ornskov said the company is spending lobbying efforts on pushing back on changes that could dismantle some of the key parts of the ACA. Specifically:

• Making sure there aren't lifetime caps, which could prevent people from getting care after they use a certain amount of benefits. This can be an issue especially for those with rare diseases, because treatments tend to be more expensive. Some of Shire's drugs, for example are among the most expensive by list price in the US.

• Ensuring children keep coverage even if their parents change jobs.

• And, less directly related to changes to the ACA, an increased transparency around getting access to medicine, "so that they don't have to have a maze of Byzantine things to go through which makes it frustrating for families," Ornskov said. "

That transparency, in some cases, can be more critical than the issue of having insurance or not.

"Oftentimes it's not 'I'm covered or I'm not covered,'" Ornskov said about patients trying to get access to medication. "It is maneuvering in a system which is very complex." For example, patients might have to answer a lot of questions before insurance can sign off on a medication, or they might come across limitations to how much of a prescription they're allowed to have.

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