noun
therapeutic drug; remedy; medicine
A drug or agent used to treat a disease or condition; often used in medical contexts.
新しい治療薬の開発が進んでいる。
Development of a new therapeutic drug is progressing.
この治療薬は副作用が少ない。
This medicine has few side effects.
治療法 means 'treatment method' or 'therapy', whereas 治療薬 is the drug itself used in treatment.
Compound of 治療 (treatment) and 薬 (drug, medicine).