Glutamine and L-Glutamine can be purchased as Glutamine or L-Glutamine, or in glutamine containing products. Glutamine containing products are protein shakes, protein powders, and protein drinks. Glutamine can be added to protein powder and protein shakes. Bodybuilders find taking glutamine to be more convenient when taken at the same time as their protein intake. L-Glutamine and glutamine often are tasteless.

The cost for a supply of glutamine (L-glutamine) ranges from about $14 to $54 and typically is sold in the form of gel capsules and powders.

However, glutamine is relatively unstable in solution, and thus glutamine powders must be consumed shortly after being mixed into solution. Some manufacturers of the supplement recommend consuming glutamine in divided dosages throughout the day. It has also been suggested that glutamine be consumed shortly before sleep (a 6-8 hours of non-eating) and after waking. It is recommended to take at least 5 grams 30 minutes before and after you train and another 5 grams before bed.

source: http://www.bodybuilding.com/fun/glutamine2.htm