Doydie I am not 85 years old but I was up to 3600 mg a day. Split over every 5 to 6 hours. She should find out when she should up her dosage. All at night?--or over the course of the day?

1800 mg was the least I was on. I started with 100 mg at night. I worked my way up when it didn't help.

Your body builds a resistance to it so you have to up the dosage. But her age does worry me. She should speak with her doctor again or maybe you could call for her.

2 x 900 mg tablets will equal 1800 mg. Or 3 x 600 tablets a day. or 6 x 300 mg a day. Spread out during the day. She will get used to it, just make sure she doesn't fall form drug hangover in the morning.