Transmutation
Level: Sorcerer 5, Wizard 5
Components: V, S, M
Casting Time: 1 round
Range: Touch
Target: One humanoid creature
Duration: 1 hour/level (D)
Saving Throw: Fortitude negates
Spell Resistance: Yes
The creature shrinks rapidly before your eyes.
This spell functions like reduce person, except as noted above.
Material Component: A pinch of powdered iron.
Note: Both greater reduce person and greater enlarge person derive from the equivalent spells in Savage Species where the duration was listed as 10 minutes/level for both. However, with these versions, greater enlarge person is now 1 hour/level (D) with a Range of Touch, but greater reduce person has been listed with the same duration and range as the original Savage Species spell. It seems reasonable to apply the updates from greater enlarge person to greater reduce person to bring them back into alignment.
Source: Spell Compendium (Page 171)