Good thinking and I have considered those options.You should talk to a Mexican cardiologist and ask his recommendation.
Unless you use MBE, you cannot have medicines mailed into Mexico. MBE has a license, but you'll pay through the nose. If you buy locally, you can apply to your insurance for reimbursement.
I have the meds sent by Estafeta through an outfit similar to MBE. I have a private mailbox for stuff that I don't want to trust to be sent to Mexico by mail.
I asked cardiologists here, but since I still see the US cardiologist, I'm not going to mix and match. My insurance doesn't cover services outside the US and the cost would be prohibitive for me, several times what it costs me travel every 4 months or so.