Medical term for the amount of a drug to be administered at one time or over a period.
The doctor adjusted the dosage based on the patient's weight.
The appropriate dose of this medicine is twice a day.
服用量 refers to the amount of medicine taken orally by a patient, while 投薬量 can include any route of administration (e.g., injection) and is often used from the prescriber's perspective.
Compound of 投薬 (とうやく, 'administration of medicine') + 量 (りょう, 'amount').