Japanese to English Medical Medical: Pharmaceuticals 導入 vs. 開始 for a drug therapy

Apologies for asking this since I'm sure the answer lies within the nearly 4,000 entries in KudoZ already for 導入, but no time (and no search filter for field on KudoZ questions!?!?)!
I'm working another (ahem) "top quality" Japanese medical journal article about a retrospective comparative study on a new-ish drug and was was bumbling along translating 導入 as "start" (thinking I had successfully avoided using some ridiculous phrasing such as "introduce a patient to [drug name]"), when all of a sudden 開始 appears, which tells me I had it wrong.
導入 is well overused in this document, but some examples are --
導入前後
[drug name]を導入した全6例
[drug name]導入数（率）
導入例
導入直前と導入後...
all looking a lot like "start" would fit the bill nicely and appearing way too many times before 開始 suddenly shows up in contrast to 導入 and tells me that 導入 is something other than "start" (or initiate or whatever) in terms of drug therapy.
Please don't tell me it's introduce. That's utterly absurd. Patient, meet drug. Drug, meet patient. Riiiight. Need another word or they're both going to be "start" since they are clearly synonymous in this instance because all who were "introduced" to it started taking it. :-)
Thanks!