Lots of spam with subjects like this:

Dear haldun, VIAGRA ® -71% OFF
Dear gonca, VIAGRA ® -61% OFF
Dear dtenney, VIAGRA ® -65% OFF
gini VIAGRA ® -63% discount

Easy to stop with a regex, but how can it be done with spamfilter?

I was thinking this:

subject:viagra,([0-9]+%)

But I don't think that will work as only the first item will search the subject. 

So I thought about doing this:

subject:viagra,subject:([0-9]+%)

That will not work either as before a regex can be used a standard keyword must be done first.

Any way I can do this?