(a) In preparing a drug prescription a pharmacist shall indicate on the drug container the name and strength of the drug contained in it, unless specifically directed otherwise by the prescribing physician, osteopathic physician, dentist, or veterinarian. If a drug is a mixture of pharmacologically active substances, only the name of the mixture need be indicated on the container, or in the absence of a name, the term “physician's mixture” may be used.
(b) In preparing a prescription, a pharmacist may not substitute a drug for a registered brand or trade name product specified unless the pharmacist obtains permission from the author of the prescription; but if the prescribing physician, osteopathic physician, dentist, or veterinarian is temporarily unavailable, the pharmacist may, if unable to supply the drug requested, substitute a drug or preparation of approximately equal therapeutic value so long as the pharmacist notifies the author of the prescription at an early opportunity.