dosology

from The Century Dictionary.

• noun What is known about the doses or quantities and combinations in which medicines should be given; the science of apportioning or dividing medicines into doses.
• noun A treatise on dosing.
• noun Also dosiology.

from the GNU version of the Collaborative International Dictionary of English.

• noun rare Posology.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun posology; the study of dosages of drugs