Hi Jan,
You could also try to cut the 180 mg Timespan pill in two and take this “new“ 90 mg Timespan am and pm.
Cutting the pill in two is allowed and possible as, at least on my Timespan, each pill is grooved in the middle. It is however not recommended to split more than once.
I fully agree with the approach described by bipedal primate: back and forth with a cautious scheme.
Good luck,
Maurice.