A preparation listed pursuant to Schedule V may be dispensed without a prescription if:
1. The preparation is dispensed only by a pharmacist directly to the person requesting the preparation;
2. The preparation is dispensed only to a person who is at least eighteen years of age;
3. The pharmacist requires the person requesting the preparation to furnish suitable identification including proof of age when appropriate;
4. The pharmacist does not dispense to any one person, or for the use of any one person or animal, any narcotic drug preparation or preparations, when he knows, or can by reasonable diligence ascertain, that such dispensing will provide the person to whom or for whose use, or the owner of the animal for the use of which, such preparation is dispensed, within 48 consecutive hours, with more than 200 milligrams of opium, or more than 270 milligrams of codeine, or more than 130 milligrams of dihydrocodeinone, or more than 65 milligrams of ethylmorphine, or more than 32 5/10 milligrams of diphenoxylate. In dispensing such a narcotic drug preparation, the pharmacist shall exercise professional discretion to ensure that the preparation is being dispensed for medical purposes only. Any pharmacist shall, at the time of dispensing, make and keep a record showing the date of dispensing, the name and quantity of the preparation, the name and address of the person to whom the preparation is dispensed, and enter his initials thereon. Such records shall be maintained as set forth in § 54.1-3404 and the regulations of the Board.