Hi, Based on the history you have shared, it is okay to split doses but duration should be six hours apart and not much delayed as therapeutic effects may not be lost due to half life of the drugs. However, skipping Furosemide to avoid dehydration is a good strategy, but Amtriptyline may not be skipped abruptly due to side effects so may be continued along. Drinking water and keeping good hydration will not interfere as water will not stay in gut for long and won t cause bulk etc., and keep you hydrated. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Saddiq Ulabidin, General & Family Physician