That's right, it's the mechanics I'm interested in, like how a health insurance company can change a person medication. This would be ludicrous where I live as they'd have very little say in what is prescribed, just what's covered.
Well, that's actually the same. The insurance company isn't dictating what medication is given. They're just dictating what the pharmacy will get paid for.
Sometimes doctors will only write prescriptions off the approved list, unless there are extreme circumstances, because they don't want to create a hardship for the patient or deal with hassle. Other times it's the pharmacy's decision.
If an insurance company decides not to cover something, the pharmacy will default to something that is covered (or covered at a more favorable rate) unless they have specific instructions from the doctor not to. Some pharmacies that have great personal service will contact the patient with that info in advance. Others will not, and it's on the patient to investigate when they notice. The last time this happened to me, my pharmacy informed me the brand-name med wasn't covered, only the generic. I opted to pay out of pocket because the formulations affected me differently.
I still got the med I wanted, and fortunately for me it was only the difference between $4 a month for generic and $15 a month for brand-name.
But I think if this thread does go on, it should probably be moved to Transatlantic Knowledge or something.