Take it immediately and don't store the solution. Take the creatine about an hour after a high carbohydrate meal. Avoid caffeine in coffee and soft drinks, because it has been reported to neutralize the positive effect of creatine. Creatine is a food supplement and does not require a doctor's prescription. The powder is available in nutrition and health food stores.
Fancy additives are unnecessary.
Just get the pure creatine from high quality sources. I think creatine is a very promising substance that certainly merits consideration by every person with ALS and indeed other disorders such as Parkinson's, Duchenne's muscular dystrophy, Sarcopenia, Obesity, Congestive Heart Failure and even Multiple Sclerosis. However I am not your individual personal physician and do not make medical recommendations. It is always wise to consult your own physician before making decisions. Keep in mind that creatine research is just now attracting the attention of large numbers of serious medical scientists.