My doctor sent a prescription to a pharmacist his clinic had a relationship with. I didn't approve this transaction. Is it legal for him to share my prescription with a pharmacist I didn't approve? I gave him the name of the pharmacist I wanted to use, and they disregarded that. Is this a violation of HIPAA?
It is not a violation. The privacy rule requires that your personal medical information be kept "private", but your consent is not required for another health care provider to process PMI. For example, your consent is not required to send samples to a particular lab for analysis, your consent is not required for the doctor to consult with a specialist. The primary health care provider can disclose information to a business associate, who is bound by the same privacy rule, the result being that your PMI cannot be "generally published" because disclosures are only allowed to those who are bound by the privacy rule (or, to whom disclosure has been authorized by the patient, e.g. to a relative).