Has anyone experience of using Amitripyline pills for a cat with urine behaviour problems

Hello, firstly I am in the UK so the medications may differ a little. First off we are not allowed to use injectable amitripyline over here. I have also tried the liquid form once but Sophie threw it up straight away. We have been giving 2.5mg of the pill for nearly two weeks but have missed it twice, once due to not being able to get it into Sophie's mouth and it was too stressful and today Sophie vomited it up with some grass. Sophie has been urinating mostly on my bed and throughout the house and I have been reading online this medication could help. I would like to know anyones experiences, how long does it take to work? Does is always work? Thank you for any advice and help.

Have you seen this thread?  It's kind of old, but speaks to your question:   http://www.thecatsite.com/t/94227/experiences-with-amitriptyline-in-cats

hope you can figure out something that works.