Pfizer please explain why you are constantly out of a S4 product that has no generic?

Pfizer, could you please explain why your subsidiary Upjohn, has been out of Relpax 8omg for the past 3 months, and the only other, the 40mm is a as a result likes hens teeth? Surely, as you are aware that there is no generic whatsoever you would ensure that you have an adequate supply of a chronic medication.