Section 20.

1. The Secretary is hereby directed to promulgate regulations exempting from any labeling or packaging requirement of this Act drugs and devices which are, in accordance with the practice of trade, to be processed, labeled, or repacked in substantial quantities at establishments other than those where originally processed or packed, on condition that such drugs and devices are not adulterated or misbranded under the provisions of this Act upon removal from such processing, labeling, or repacking establishment.

2. 1. Drugs intended for use by man which:

      1. are habit-forming;

      2. because of their toxicity or other potentiality for harmful effect, or the method of their use is not safe for use except under the supervision of practitioner licensed by law to administer such drug:

      3. are new drugs whose applications are limited to investigational use;

      shall be dispensed only (1) upon a written prescription of a practitioner licensed by law to administer such drug, or (2) upon an oral prescription of such practitioner which is reduced promptly to writing and filed by the pharmacists, or (3) by refilling any such written or oral prescription if such refilling is authorized by the prescriber either in the original prescription or by an oral order which is reduced promptly to writing and filed by the pharmacist. The act of dispensing a drug contrary to the provisions of this paragraph shall be deemed to be an act which results in the drug being misbranded while held for sale.

   2. Any drug dispensed by filling or refilling a written prescription of a practitioner licensed by law to administer such drug shall be exempt from the requirements of Section nineteen, except paragraphs (a), (i)(2) and (3) and the packaging requirements of paragraphs (g) and (h), if the drug bears a label containing the name and address of the dispenser, the serial number and date of the prescription or its filling, the name of the prescriber, and, if stated in the prescription the name of the patient, and the directions for use and cautionary statements, if any, contained in such prescription.

   3. The Secretary may by regulation remove drugs subject to Section nineteen (d) and Sections twenty-one and twenty-one-B from the requirements of subsection (b)(1) of this Section, when such requirements are not necessary for the protection of the public health.

   4. A drug which is subject to subsection (b)(1) of this Section shall be deemed to be misbranded if at any time prior to dispensing, its label fails to bear the statement "Caution: Foods, Drugs and Devices, and Cosmetics Law prohibits dispensing without prescription". A drug to which subsection (b)(1) of this Section does not apply shall be deemed to be misbranded if at any time prior to dispensing, its label bears the caution statement quoted in the preceding sentence.