I'm sorry your brother has HE. For themister, this is the very worst part of liver disease. Here is a link to the documentary for you. www.hesback.com
Medications really interfere with HE and make it so much worse. The worst offenders are Ambien, pain meds like oxycodone, anti-anxiety meds (xanax), and many anti-depressants. A lot of liver folks also take meds for other things, or for depression and insomnia. But, once HE comes into the picture, those meds that never caused any sides in the past can trigger significant HE episodes. Some do fine on lactulose alone. Most seem to take Xifaxan and lactulose.
Is your brother on the transplant list? If he is eligible and interested, now would be a good time to be evaluated for a transplant. Big Hugs