This is the first time I've posted so I'm a little nervous.  I hope someone can advise me.
My 10 month old ckcs is having a phantom pregnancy and apart from producing milk she is her usual happy little self.  We took her to the vets yesterday and have been prescribed Galastop, she had her first dose last night and that's when our problem started.
We have a 3 year old cat who has so far got along reasonably well with Cassie until last night when she became very aggressive and actually launched herself at Cassie while hissing and spitting.  We've never seen our cat act like this before and we are currently keeping them in separate parts of the house as I'm really worried she's going to cause Cassie some serious harm as she still keeps trying to get at her.
This seems to be a really silly question but is it possible that her medication could be making her give off some sort of odour that is driving the cat wild?
I'm hoping that there's someone could give me any ideas on how to resolve this.

It could be the hormones in your bitch that are causing the reaction rather than the medication, Never had the reaction in any of my cats to my bicthes but my cats have always been very laid back & used to dogs from the first day we get them, they were also all tom(well ex tom cats ;) ) cats

If your cat launches another attack the use of a water pistol on the cat might help as cats usually don't like being wet & it can't harm him/her

Thanks, I'll try the water pistol & see how it goes.  She's normally laid back and lazy so the change was really sudden and a bit scarey.
I'll let you know how it goes.