In traditional Tibetan medicine, it is common to enchant or bless medicines before administering them so that they will be more effective. Typically this is done by reciting a mantra over the medicine and then possibly also blowing on it. In the gZungs 'Dus (Collection of Dharanis), there is an entry titled, "Mantra for Enchanting Medicines When Administering Them." In actual fact, the mantra given is the standard or most common form of the Medicine Buddha mantra. To bless medicines with this mantra, it is best to have previously said this mantra 100,000 or even a million or more times. In Tibetan Buddhism, blessing something with a mantra is an "activity (lay-jor)" that requires already having done the "approach and accomplishment (nyen-drub)" of that Deity and His or Her root mantra. Having done the preliminary approach and accomplishment, one then has the actual power to use that mantra to perform this or that magical activity.
Be that as it may, below is my translation of this section of the gZungs 'Dus. Persons wishing to use this mantra to bless medicines may recite this mantra as many times as possible while visualizing the Medicine Buddha in front of them. Think that one offers up a vast ocean of offerings to the Medicine Buddha. The Medicine Buddha is pleased with these offerings and emits rays of light from His heart. These rays of light stream back down to the medicine, imbuing them with His blessings. Thus think that now this medicine embodies all the power and blessings of the Medicine Buddha.
Because this mantra comes from the Kangyur, it does not need oral transmission or empowerment (although those will make it even more powerful). So anyone with a good heart and sincere compassion can use this mantra for the sake of helping both oneself and others.
Mantra for Enchanting Medicines When Administering Them
I prostrate to the Three Jewels.
CHOM-DEN-DAY DE-ZHIN-SHEG-PA DRA-CHOM-PA YANG-DAG-PAR DZOG-PAI SANG-GAY MEN-GYI-LA BAIDURYA OD-KYI GYAL-PO-LA CHAG-TSHAL-LO
I to the Bhagawat, Tathgata, Arhat, totally [and] completely perfected Buddha Bhaisajya-guru, King of Sapphire Light.
OM BE-KAN-ZE BE-KAN-ZE
BE-KAN-ZE SA-MUD-GA-TE SO-HA
[Thus] the Mantra for Enchanting Medicines When Administering Them is completed.