Running an agile method in a validated project?

Many of the principles of agile development sounds really good to me.
The one I like the most is the frequent delivery to enable continious feedback.

At the moment I am in a project on a pharma company that is regulated by validation rules.That means that with every delivery with new requirements implemented there comes loads of formal testing and validation work.

Dont know the rules of validating systems very well but there seems to be an administrative barrier that is doing frequent delivery impossible.Right now, in the worst cases we have around one year from construction to delivery of new functionality.So even if we did the right thing one year ago, is that what the customer wants today? Not for sure...

My question is: Is there anyone with experience on how to come around this problem and speed the delivery frequency in a validated project?