I would guess that it will be at least 14 years before a liquid generic zidua would be available. Patent for liquid was applied for 1 year ago. I am unsure if this patent would last 15 or 20 years and when the start date of patent would be. Appears that there is no reason to get a patent on a liquid formulation of chemical when there is active patent on the chemical itself. 

The supply might not be that low, chemical could already be made and sitting in a warehouse just waiting to be shipped to US.

 https://patents.google.com/patent/WO2024042134A1/en